Version 3.39.3 patches applied to the begin-concurrent branch.

FossilOrigin-Name: 31304de83ef1dbb186f1776a57eee3f1185f23870352ea4e7e50d204a812fb9c
Version 3.39.3
2022-09-05 12:39:06 +00:00 · 2022-09-05 11:02:23 +00:00 · 2022-09-02 21:21:58 +00:00 · 2022-09-02 19:18:49 +00:00 · 2022-09-02 17:26:22 +00:00 · 2022-09-02 16:45:21 +00:00
84 changed files with 7478 additions and 578 deletions
@@ -433,6 +433,7 @@ TESTSRC = \
  $(TOP)/ext/fts3/fts3_term.c \
  $(TOP)/ext/fts3/fts3_test.c  \
  $(TOP)/ext/session/test_session.c \
+  $(TOP)/ext/session/sqlite3changebatch.c \
  $(TOP)/ext/rbu/test_rbu.c 

 # Statically linked extensions
@@ -503,6 +504,7 @@ TESTSRC2 = \
  $(TOP)/src/pcache1.c \
  $(TOP)/src/select.c \
  $(TOP)/src/tokenize.c \
+  $(TOP)/src/treeview.c \
  $(TOP)/src/utf.c \
  $(TOP)/src/util.c \
  $(TOP)/src/vdbeapi.c \
@@ -523,8 +525,9 @@ TESTSRC2 = \
  $(TOP)/ext/fts3/fts3_tokenizer.c \
  $(TOP)/ext/fts3/fts3_write.c \
  $(TOP)/ext/async/sqlite3async.c \
-  $(TOP)/ext/session/sqlite3session.c \
  $(TOP)/ext/misc/stmt.c \
+  $(TOP)/ext/session/sqlite3session.c \
+  $(TOP)/ext/session/test_session.c \
  fts5.c

 # Header files used by all library source files.
@@ -874,7 +877,7 @@ hash.lo:	$(TOP)/src/hash.c $(HDR)
 insert.lo:	$(TOP)/src/insert.c $(HDR)
 	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/insert.c

-json.lo:	$(TOP)/src/json.c
+json.lo:	$(TOP)/src/json.c $(HDR)
 	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/json.c

 legacy.lo:	$(TOP)/src/legacy.c $(HDR)
@@ -1 +1 @@
-3.39.0
+3.39.3
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for sqlite 3.39.0.
+# Generated by GNU Autoconf 2.69 for sqlite 3.39.3.
 #
 #
 # Copyright (C) 1992-1996, 1998-2012 Free Software Foundation, Inc.
@@ -726,8 +726,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='sqlite'
 PACKAGE_TARNAME='sqlite'
-PACKAGE_VERSION='3.39.0'
-PACKAGE_STRING='sqlite 3.39.0'
+PACKAGE_VERSION='3.39.3'
+PACKAGE_STRING='sqlite 3.39.3'
 PACKAGE_BUGREPORT=''
 PACKAGE_URL=''

@@ -1468,7 +1468,7 @@ if test "$ac_init_help" = "long"; then
  # Omit some internal or obsolete options to make the list less imposing.
  # This message is too long to be a string in the A/UX 3.1 sh.
  cat <<_ACEOF
-\`configure' configures sqlite 3.39.0 to adapt to many kinds of systems.
+\`configure' configures sqlite 3.39.3 to adapt to many kinds of systems.

 Usage: $0 [OPTION]... [VAR=VALUE]...

@@ -1533,7 +1533,7 @@ fi

 if test -n "$ac_init_help"; then
  case $ac_init_help in
-     short | recursive ) echo "Configuration of sqlite 3.39.0:";;
+     short | recursive ) echo "Configuration of sqlite 3.39.3:";;
   esac
  cat <<\_ACEOF

@@ -1661,7 +1661,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
  cat <<\_ACEOF
-sqlite configure 3.39.0
+sqlite configure 3.39.3
 generated by GNU Autoconf 2.69

 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2080,7 +2080,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.

-It was created by sqlite $as_me 3.39.0, which was
+It was created by sqlite $as_me 3.39.3, which was
 generated by GNU Autoconf 2.69.  Invocation command line was

  $ $0 $@
@@ -12390,7 +12390,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by sqlite $as_me 3.39.0, which was
+This file was extended by sqlite $as_me 3.39.3, which was
 generated by GNU Autoconf 2.69.  Invocation command line was

  CONFIG_FILES    = $CONFIG_FILES
@@ -12456,7 +12456,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-sqlite config.status 3.39.0
+sqlite config.status 3.39.3
 configured by $0, generated by GNU Autoconf 2.69,
  with options \\"\$ac_cs_config\\"

@@ -0,0 +1,106 @@
+
+Begin Concurrent
+================
+
+## Overview
+
+Usually, SQLite allows at most one writer to proceed concurrently. The
+BEGIN CONCURRENT enhancement allows multiple writers to process write
+transactions simultanously if the database is in "wal" or "wal2" mode,
+although the system still serializes COMMIT commands.
+
+When a write-transaction is opened with "BEGIN CONCURRENT", actually 
+locking the database is deferred until a COMMIT is executed. This means
+that any number of transactions started with BEGIN CONCURRENT may proceed
+concurrently. The system uses optimistic page-level-locking to prevent
+conflicting concurrent transactions from being committed.
+
+When a BEGIN CONCURRENT transaction is committed, the system checks whether 
+or not any of the database pages that the transaction has read have been
+modified since the BEGIN CONCURRENT was opened. In other words - it asks 
+if the transaction being committed operates on a different set of data than
+all other concurrently executing transactions. If the answer is "yes, this
+transaction did not read or modify any data modified by any concurrent
+transaction", then the transaction is committed as normal. Otherwise, if the
+transaction does conflict, it cannot be committed and an SQLITE&#95;BUSY&#95;SNAPSHOT
+error is returned. At this point, all the client can do is ROLLBACK the
+transaction.
+
+If SQLITE&#95;BUSY&#95;SNAPSHOT is returned, messages are output via the sqlite3&#95;log
+mechanism indicating the page and table or index on which the conflict
+occurred. This can be useful when optimizing concurrency.
+
+## Application Programming Notes
+
+In order to serialize COMMIT processing, SQLite takes a lock on the database
+as part of each COMMIT command and releases it before returning. At most one
+writer may hold this lock at any one time. If a writer cannot obtain the lock,
+it uses SQLite's busy-handler to pause and retry for a while:
+
+  <a href=https://www.sqlite.org/c3ref/busy_handler.html>
+      https://www.sqlite.org/c3ref/busy_handler.html
+  </a>
+
+If there is significant contention for the writer lock, this mechanism can be
+inefficient. In this case it is better for the application to use a mutex or
+some other mechanism that supports blocking to ensure that at most one writer
+is attempting to COMMIT a BEGIN CONCURRENT transaction at a time. This is
+usually easier if all writers are part of the same operating system process.
+
+If all database clients (readers and writers) are located in the same OS
+process, and if that OS is a Unix variant, then it can be more efficient to
+the built-in VFS "unix-excl" instead of the default "unix". This is because it
+uses more efficient locking primitives.
+
+The key to maximizing concurrency using BEGIN CONCURRENT is to ensure that
+there are a large number of non-conflicting transactions. In SQLite, each
+table and each index is stored as a separate b-tree, each of which is
+distributed over a discrete set of database pages. This means that:
+
+  * Two transactions that write to different sets of tables never 
+    conflict, and that
+
+  * Two transactions that write to the same tables or indexes only 
+    conflict if the values of the keys (either primary keys or indexed 
+    rows) are fairly close together. For example, given a large 
+    table with the schema:
+
+      <pre>     CREATE TABLE t1(a INTEGER PRIMARY KEY, b BLOB);</pre>
+
+    writing two rows with adjacent values for "a" probably will cause a
+    conflict (as the two keys are stored on the same page), but writing two
+    rows with vastly different values for "a" will not (as the keys will likly
+    be stored on different pages).
+
+Note that, in SQLite, if values are not explicitly supplied for an INTEGER
+PRIMARY KEY, as for example in:
+
+>
+     INSERT INTO t1(b) VALUES(<blob-value>);
+
+then monotonically increasing values are assigned automatically. This is
+terrible for concurrency, as it all but ensures that all new rows are 
+added to the same database page. In such situations, it is better to
+explicitly assign random values to INTEGER PRIMARY KEY fields.
+
+This problem also comes up for non-WITHOUT ROWID tables that do not have an
+explicit INTEGER PRIMARY KEY column. In these cases each table has an implicit
+INTEGER PRIMARY KEY column that is assigned increasing values, leading to the
+same problem as omitting to assign a value to an explicit INTEGER PRIMARY KEY
+column.
+
+For both explicit and implicit INTEGER PRIMARY KEYs, it is possible to have
+SQLite assign values at random (instead of the monotonically increasing
+values) by writing a row with a rowid equal to the largest possible signed
+64-bit integer to the table. For example:
+
+     INSERT INTO t1(a) VALUES(9223372036854775807);
+
+Applications should take care not to malfunction due to the presence of such
+rows.
+
+The nature of some types of indexes, for example indexes on timestamp fields,
+can also cause problems (as concurrent transactions may assign similar
+timestamps that will be stored on the same db page to new records). In these
+cases the database schema may need to be rethought to increase the concurrency
+provided by page-level-locking.
@@ -4308,8 +4308,7 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
  char *aPoslist = 0;             /* Position list for deferred tokens */
  int nPoslist = 0;               /* Number of bytes in aPoslist */
  int iPrev = -1;                 /* Token number of previous deferred token */
-
-  assert( pPhrase->doclist.bFreeList==0 );
+  char *aFree = (pPhrase->doclist.bFreeList ? pPhrase->doclist.pList : 0);

  for(iToken=0; iToken<pPhrase->nToken; iToken++){
    Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
@@ -4323,6 +4322,7 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){

      if( pList==0 ){
        sqlite3_free(aPoslist);
+        sqlite3_free(aFree);
        pPhrase->doclist.pList = 0;
        pPhrase->doclist.nList = 0;
        return SQLITE_OK;
@@ -4343,6 +4343,7 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
        nPoslist = (int)(aOut - aPoslist);
        if( nPoslist==0 ){
          sqlite3_free(aPoslist);
+          sqlite3_free(aFree);
          pPhrase->doclist.pList = 0;
          pPhrase->doclist.nList = 0;
          return SQLITE_OK;
@@ -4375,13 +4376,14 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
        nDistance = iPrev - nMaxUndeferred;
      }

-      aOut = (char *)sqlite3_malloc(nPoslist+8);
+      aOut = (char *)sqlite3Fts3MallocZero(nPoslist+FTS3_BUFFER_PADDING);
      if( !aOut ){
        sqlite3_free(aPoslist);
        return SQLITE_NOMEM;
      }
      
      pPhrase->doclist.pList = aOut;
+      assert( p1 && p2 );
      if( fts3PoslistPhraseMerge(&aOut, nDistance, 0, 1, &p1, &p2) ){
        pPhrase->doclist.bFreeList = 1;
        pPhrase->doclist.nList = (int)(aOut - pPhrase->doclist.pList);
@@ -4394,6 +4396,7 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
    }
  }

+  if( pPhrase->doclist.pList!=aFree ) sqlite3_free(aFree);
  return SQLITE_OK;
 }
 #endif /* SQLITE_DISABLE_FTS4_DEFERRED */
@@ -5568,11 +5571,10 @@ static int fts3EvalTestExpr(

      default: {
 #ifndef SQLITE_DISABLE_FTS4_DEFERRED
-        if( pCsr->pDeferred 
-         && (pExpr->iDocid==pCsr->iPrevId || pExpr->bDeferred)
-        ){
+        if( pCsr->pDeferred && (pExpr->bDeferred || (
+            pExpr->iDocid==pCsr->iPrevId && pExpr->pPhrase->doclist.pList
+        ))){
          Fts3Phrase *pPhrase = pExpr->pPhrase;
-          assert( pExpr->bDeferred || pPhrase->doclist.bFreeList==0 );
          if( pExpr->bDeferred ){
            fts3EvalInvalidatePoslist(pPhrase);
          }
@@ -16,12 +16,16 @@ source [file join [file dirname [info script]] fts5_common.tcl]
 source $testdir/malloc_common.tcl
 set testprefix fts5fault4

-# If SQLITE_ENABLE_FTS3 is defined, omit this file.
+# If SQLITE_ENABLE_FTS5 is not defined, omit this file.
 ifcapable !fts5 {
  finish_test
  return
 }

+set ::TMPDBERROR [list 1 \
+  {unable to open a temporary database file for storing temporary tables}
+]
+
 #-------------------------------------------------------------------------
 # An OOM while dropping an fts5 table.
 #
@@ -391,7 +395,7 @@ do_faultsim_test 14.1 -faults oom-t* -prep {
 } -body {
  db eval { ALTER TABLE "tbl one" RENAME TO "tbl two" }
 } -test {
-  faultsim_test_result {0 {}}
+  faultsim_test_result {0 {}} $::TMPDBERROR
 }

 finish_test
@@ -685,7 +685,7 @@ static const char *re_compile(ReCompiled **ppRe, const char *zIn, int noCase){
        pRe->zInit[j++] = (unsigned char)(0xc0 | (x>>6));
        pRe->zInit[j++] = 0x80 | (x&0x3f);
      }else if( x<=0xffff ){
-        pRe->zInit[j++] = (unsigned char)(0xd0 | (x>>12));
+        pRe->zInit[j++] = (unsigned char)(0xe0 | (x>>12));
        pRe->zInit[j++] = 0x80 | ((x>>6)&0x3f);
        pRe->zInit[j++] = 0x80 | (x&0x3f);
      }else{
@@ -30,6 +30,16 @@ SQLITE_EXTENSION_INIT1

 #ifndef SQLITE_OMIT_VIRTUALTABLE

+
+#define STMT_NUM_INTEGER_COLUMN 10
+typedef struct StmtRow StmtRow;
+struct StmtRow {
+  sqlite3_int64 iRowid;                /* Rowid value */
+  char *zSql;                          /* column "sql" */
+  int aCol[STMT_NUM_INTEGER_COLUMN+1]; /* all other column values */
+  StmtRow *pNext;                      /* Next row to return */
+};
+
 /* stmt_vtab is a subclass of sqlite3_vtab which will
 ** serve as the underlying representation of a stmt virtual table
 */
@@ -47,8 +57,7 @@ typedef struct stmt_cursor stmt_cursor;
 struct stmt_cursor {
  sqlite3_vtab_cursor base;  /* Base class - must be first */
  sqlite3 *db;               /* Database connection for this cursor */
-  sqlite3_stmt *pStmt;       /* Statement cursor is currently pointing at */
-  sqlite3_int64 iRowid;      /* The rowid */
+  StmtRow *pRow;             /* Current row */
 };

 /*
@@ -92,7 +101,7 @@ static int stmtConnect(
     "CREATE TABLE x(sql,ncol,ro,busy,nscan,nsort,naidx,nstep,"
                    "reprep,run,mem)");
  if( rc==SQLITE_OK ){
-    pNew = sqlite3_malloc( sizeof(*pNew) );
+    pNew = sqlite3_malloc64( sizeof(*pNew) );
    *ppVtab = (sqlite3_vtab*)pNew;
    if( pNew==0 ) return SQLITE_NOMEM;
    memset(pNew, 0, sizeof(*pNew));
@@ -114,7 +123,7 @@ static int stmtDisconnect(sqlite3_vtab *pVtab){
 */
 static int stmtOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  stmt_cursor *pCur;
-  pCur = sqlite3_malloc( sizeof(*pCur) );
+  pCur = sqlite3_malloc64( sizeof(*pCur) );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur));
  pCur->db = ((stmt_vtab*)p)->db;
@@ -122,10 +131,21 @@ static int stmtOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  return SQLITE_OK;
 }

+static void stmtCsrReset(stmt_cursor *pCur){
+  StmtRow *pRow = 0;
+  StmtRow *pNext = 0;
+  for(pRow=pCur->pRow; pRow; pRow=pNext){
+    pNext = pRow->pNext;
+    sqlite3_free(pRow);
+  }
+  pCur->pRow = 0;
+}
+
 /*
 ** Destructor for a stmt_cursor.
 */
 static int stmtClose(sqlite3_vtab_cursor *cur){
+  stmtCsrReset((stmt_cursor*)cur);
  sqlite3_free(cur);
  return SQLITE_OK;
 }
@@ -136,8 +156,9 @@ static int stmtClose(sqlite3_vtab_cursor *cur){
 */
 static int stmtNext(sqlite3_vtab_cursor *cur){
  stmt_cursor *pCur = (stmt_cursor*)cur;
-  pCur->iRowid++;
-  pCur->pStmt = sqlite3_next_stmt(pCur->db, pCur->pStmt);
+  StmtRow *pNext = pCur->pRow->pNext;
+  sqlite3_free(pCur->pRow);
+  pCur->pRow = pNext;
  return SQLITE_OK;
 }

@@ -151,39 +172,11 @@ static int stmtColumn(
  int i                       /* Which column to return */
 ){
  stmt_cursor *pCur = (stmt_cursor*)cur;
-  switch( i ){
-    case STMT_COLUMN_SQL: {
-      sqlite3_result_text(ctx, sqlite3_sql(pCur->pStmt), -1, SQLITE_TRANSIENT);
-      break;
-    }
-    case STMT_COLUMN_NCOL: {
-      sqlite3_result_int(ctx, sqlite3_column_count(pCur->pStmt));
-      break;
-    }
-    case STMT_COLUMN_RO: {
-      sqlite3_result_int(ctx, sqlite3_stmt_readonly(pCur->pStmt));
-      break;
-    }
-    case STMT_COLUMN_BUSY: {
-      sqlite3_result_int(ctx, sqlite3_stmt_busy(pCur->pStmt));
-      break;
-    }
-    default: {
-      assert( i==STMT_COLUMN_MEM );
-      i = SQLITE_STMTSTATUS_MEMUSED + 
-            STMT_COLUMN_NSCAN - SQLITE_STMTSTATUS_FULLSCAN_STEP;
-      /* Fall thru */
-    }
-    case STMT_COLUMN_NSCAN:
-    case STMT_COLUMN_NSORT:
-    case STMT_COLUMN_NAIDX:
-    case STMT_COLUMN_NSTEP:
-    case STMT_COLUMN_REPREP:
-    case STMT_COLUMN_RUN: {
-      sqlite3_result_int(ctx, sqlite3_stmt_status(pCur->pStmt,
-                      i-STMT_COLUMN_NSCAN+SQLITE_STMTSTATUS_FULLSCAN_STEP, 0));
-      break;
-    }
+  StmtRow *pRow = pCur->pRow;
+  if( i==STMT_COLUMN_SQL ){
+    sqlite3_result_text(ctx, pRow->zSql, -1, SQLITE_TRANSIENT);
+  }else{
+    sqlite3_result_int(ctx, pRow->aCol[i]);
  }
  return SQLITE_OK;
 }
@@ -194,7 +187,7 @@ static int stmtColumn(
 */
 static int stmtRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  stmt_cursor *pCur = (stmt_cursor*)cur;
-  *pRowid = pCur->iRowid;
+  *pRowid = pCur->pRow->iRowid;
  return SQLITE_OK;
 }

@@ -204,7 +197,7 @@ static int stmtRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
 */
 static int stmtEof(sqlite3_vtab_cursor *cur){
  stmt_cursor *pCur = (stmt_cursor*)cur;
-  return pCur->pStmt==0;
+  return pCur->pRow==0;
 }

 /*
@@ -219,9 +212,53 @@ static int stmtFilter(
  int argc, sqlite3_value **argv
 ){
  stmt_cursor *pCur = (stmt_cursor *)pVtabCursor;
-  pCur->pStmt = 0;
-  pCur->iRowid = 0;
-  return stmtNext(pVtabCursor);
+  sqlite3_stmt *p = 0;
+  sqlite3_int64 iRowid = 1;
+  StmtRow **ppRow = 0;
+
+  stmtCsrReset(pCur);
+  ppRow = &pCur->pRow;
+  for(p=sqlite3_next_stmt(pCur->db, 0); p; p=sqlite3_next_stmt(pCur->db, p)){
+    const char *zSql = sqlite3_sql(p);
+    sqlite3_int64 nSql = zSql ? strlen(zSql)+1 : 0;
+    StmtRow *pNew = (StmtRow*)sqlite3_malloc64(sizeof(StmtRow) + nSql);
+
+    if( pNew==0 ) return SQLITE_NOMEM;
+    memset(pNew, 0, sizeof(StmtRow));
+    if( zSql ){
+      pNew->zSql = (char*)&pNew[1];
+      memcpy(pNew->zSql, zSql, nSql);
+    }
+    pNew->aCol[STMT_COLUMN_NCOL] = sqlite3_column_count(p);
+    pNew->aCol[STMT_COLUMN_RO] = sqlite3_stmt_readonly(p);
+    pNew->aCol[STMT_COLUMN_BUSY] = sqlite3_stmt_busy(p);
+    pNew->aCol[STMT_COLUMN_NSCAN] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_FULLSCAN_STEP, 0
+    );
+    pNew->aCol[STMT_COLUMN_NSORT] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_SORT, 0
+    );
+    pNew->aCol[STMT_COLUMN_NAIDX] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_AUTOINDEX, 0
+    );
+    pNew->aCol[STMT_COLUMN_NSTEP] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_VM_STEP, 0
+    );
+    pNew->aCol[STMT_COLUMN_REPREP] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_REPREPARE, 0
+    );
+    pNew->aCol[STMT_COLUMN_RUN] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_RUN, 0
+    );
+    pNew->aCol[STMT_COLUMN_MEM] = sqlite3_stmt_status(
+        p, SQLITE_STMTSTATUS_MEMUSED, 0
+    );
+    pNew->iRowid = iRowid++;
+    *ppRow = pNew;
+    ppRow = &pNew->pNext;
+  }
+
+  return SQLITE_OK;
 }

 /*
@@ -1695,7 +1695,7 @@ static int geopolyUpdate(
      sqlite3_free(p);
      nChange = 1;
    }
-    for(jj=1; jj<pRtree->nAux; jj++){
+    for(jj=1; jj<nData-2; jj++){
      nChange++;
      sqlite3_bind_value(pUp, jj+2, aData[jj+2]);
    }
@@ -23,6 +23,10 @@ ifcapable !rtree {
  return
 }

+set ::TMPDBERROR [list 1 \
+  {unable to open a temporary database file for storing temporary tables}
+]
+
 # Test summary:
 #
 #   rtree3-1: Test OOM in simple CREATE TABLE, INSERT, DELETE and SELECT 
@@ -196,9 +200,9 @@ do_test rtree3-7.prep {
 do_faultsim_test rtree3-7 -faults oom-* -prep {
  faultsim_restore_and_reopen
 } -body {
-  execsql { ALTER TABLE rt RENAME TO rt2 }
+  execsql { ALTER TABLE rt RENAME TO rt2 } 
 } -test {
-  faultsim_test_result {0 {}}
+  faultsim_test_result {0 {}} $::TMPDBERROR
 }

 do_faultsim_test rtree3-8 -faults oom-* -prep {
@@ -0,0 +1,222 @@
+# 2016 August 23
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.
+#
+
+if {![info exists testdir]} {
+  set testdir [file join [file dirname [info script]] .. .. test]
+} 
+source $testdir/tester.tcl
+ifcapable !session {finish_test; return}
+
+set testprefix changebatch1
+
+
+proc sql_to_changeset {method sql} {
+  sqlite3session S db main
+  S attach *
+  execsql $sql
+  set ret [S $method]
+  S delete
+  return $ret
+}
+
+proc do_changebatch_test {tn method args} {
+  set C [list]
+  foreach a $args {
+    lappend C [sql_to_changeset $method $a]
+  }
+
+  sqlite3changebatch cb db
+  set i 1
+  foreach ::cs [lrange $C 0 end-1] {
+    set rc [cb add $::cs]
+    if {$rc!="SQLITE_OK"} { error "expected SQLITE_OK, got $rc (i=$i)" }
+    incr i
+  }
+
+  set ::cs [lindex $C end]
+  do_test $tn { cb add [set ::cs] } SQLITE_CONSTRAINT
+  cb delete
+}
+
+proc do_changebatch_test1 {tn args} {
+  uplevel do_changebatch_test $tn changeset $args
+}
+proc do_changebatch_test2 {tn args} {
+  uplevel do_changebatch_test $tn fullchangeset $args
+}
+
+#-------------------------------------------------------------------------
+# The body of the following loop contains tests for database schemas
+# that do not feature multi-column UNIQUE constraints. In this case
+# it doesn't matter if the changesets are generated using
+# sqlite3session_changeset() or sqlite3session_fullchangeset().
+#
+foreach {tn testfunction} {
+  1 do_changebatch_test1
+  2 do_changebatch_test2
+} {
+  reset_db
+
+  #-------------------------------------------------------------------------
+  #
+  do_execsql_test $tn.1.0 {
+    CREATE TABLE t1(a PRIMARY KEY, b);
+  }
+  
+  $testfunction $tn.1.1 {
+    INSERT INTO t1 VALUES(1, 1);
+  } {
+    DELETE FROM t1 WHERE a=1;
+  }
+  
+  do_execsql_test $tn.1.2.0 {
+    INSERT INTO t1 VALUES(1, 1);
+    INSERT INTO t1 VALUES(2, 2);
+    INSERT INTO t1 VALUES(3, 3);
+  }
+  $testfunction $tn.1.2.1 {
+    DELETE FROM t1 WHERE a=2;
+  } {
+    INSERT INTO t1 VALUES(2, 2);
+  }
+  
+  #-------------------------------------------------------------------------
+  #
+  do_execsql_test $tn.2.0 {
+    CREATE TABLE x1(a, b PRIMARY KEY, c UNIQUE);
+    CREATE TABLE x2(a PRIMARY KEY, b UNIQUE, c UNIQUE);
+    CREATE INDEX x1a ON x1(a);
+  
+    INSERT INTO x1 VALUES(1, 1, 'a');
+    INSERT INTO x1 VALUES(1, 2, 'b');
+    INSERT INTO x1 VALUES(1, 3, 'c');
+  }
+  
+  $testfunction $tn.2.1 {
+    DELETE FROM x1 WHERE b=2;
+  } {
+    UPDATE x1 SET c='b' WHERE b=3;
+  }
+  
+  $testfunction $tn.2.2 {
+    DELETE FROM x1 WHERE b=1;
+  } {
+    INSERT INTO x1 VALUES(1, 5, 'a');
+  }
+
+  set L [list]
+  for {set i 1000} {$i < 10000} {incr i} {
+    lappend L "INSERT INTO x2 VALUES($i, $i, 'x' || $i)"
+  }
+  lappend L "DELETE FROM x2 WHERE b=1005"
+  $testfunction $tn.2.3 {*}$L
+
+  execsql { INSERT INTO x1 VALUES('f', 'f', 'f') }
+  $testfunction $tn.2.4 {
+    INSERT INTO x2 VALUES('f', 'f', 'f');
+  } {
+    INSERT INTO x1 VALUES('g', 'g', 'g');
+  } {
+    DELETE FROM x1 WHERE b='f';
+  } {
+    INSERT INTO x2 VALUES('g', 'g', 'g');
+  } {
+    INSERT INTO x1 VALUES('f', 'f', 'f');
+  }
+
+  execsql {
+    DELETE FROM x1;
+    INSERT INTO x1 VALUES(1.5, 1.5, 1.5);
+  }
+  $testfunction $tn.2.5 {
+    DELETE FROM x1 WHERE b BETWEEN 1 AND 2;
+  } {
+    INSERT INTO x1 VALUES(2.5, 2.5, 2.5);
+  } {
+    INSERT INTO x1 VALUES(1.5, 1.5, 1.5);
+  }
+
+  execsql {
+    DELETE FROM x2;
+    INSERT INTO x2 VALUES(X'abcd', X'1234', X'7890');
+    INSERT INTO x2 VALUES(X'0000', X'0000', X'0000');
+  }
+  breakpoint
+  $testfunction $tn.2.6 {
+    UPDATE x2 SET c = X'1234' WHERE a=X'abcd';
+    INSERT INTO x2 VALUES(X'1234', X'abcd', X'7890');
+  } {
+    DELETE FROM x2 WHERE b=X'0000';
+  } {
+    INSERT INTO x2 VALUES(1, X'0000', NULL);
+  }
+}
+
+#-------------------------------------------------------------------------
+# Test some multi-column UNIQUE constraints. First Using _changeset() to
+# demonstrate the problem, then using _fullchangeset() to show that it has
+# been fixed.
+#
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE y1(a PRIMARY KEY, b, c, UNIQUE(b, c));
+  INSERT INTO y1 VALUES(1, 1, 1);
+  INSERT INTO y1 VALUES(2, 2, 2);
+  INSERT INTO y1 VALUES(3, 3, 3);
+  INSERT INTO y1 VALUES(4, 3, 4);
+  BEGIN;
+}
+
+do_test 3.1.1 {
+  set c1 [sql_to_changeset changeset { DELETE FROM y1 WHERE a=4    }]
+  set c2 [sql_to_changeset changeset { UPDATE y1 SET c=4 WHERE a=3 }]
+  sqlite3changebatch cb db
+  cb add $c1
+  cb add $c2
+} {SQLITE_OK}
+do_test 3.1.2 {
+  cb delete
+  execsql ROLLBACK
+} {}
+
+do_test 3.1.1 {
+  set c1 [sql_to_changeset fullchangeset { DELETE FROM y1 WHERE a=4    }]
+  set c2 [sql_to_changeset fullchangeset { UPDATE y1 SET c=4 WHERE a=3 }]
+  sqlite3changebatch cb db
+  cb add $c1
+  cb add $c2
+} {SQLITE_CONSTRAINT}
+do_test 3.1.2 {
+  cb delete
+} {}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 4.0 {
+  CREATE TABLE t1(x, y, z, PRIMARY KEY(x, y), UNIQUE(z));
+}
+
+do_test 4.1 {
+  set c1 [sql_to_changeset fullchangeset { INSERT INTO t1 VALUES(1, 2, 3) }]
+  execsql {
+    DROP TABLE t1;
+    CREATE TABLE t1(w, x, y, z, PRIMARY KEY(x, y), UNIQUE(z));
+  }
+  sqlite3changebatch cb db
+  list [catch { cb add $c1 } msg] $msg
+} {1 SQLITE_RANGE}
+
+
+
+finish_test
@@ -0,0 +1,42 @@
+# 2011 Mar 21
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# The focus of this file is testing the session module.
+#
+
+if {![info exists testdir]} {
+  set testdir [file join [file dirname [info script]] .. .. test]
+} 
+source [file join [file dirname [info script]] session_common.tcl]
+source $testdir/tester.tcl
+ifcapable !session {finish_test; return}
+set testprefix changebatchfault
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c PRIMARY KEY, UNIQUE(a, b));
+  INSERT INTO t1 VALUES('a', 'a', 'a');
+  INSERT INTO t1 VALUES('b', 'b', 'b');
+}
+
+set ::c1 [changeset_from_sql { delete from t1 where c='a' }]
+set ::c2 [changeset_from_sql { insert into t1 values('c', 'c', 'c') }]
+
+do_faultsim_test 1 -faults oom-* -body {
+  sqlite3changebatch cb db
+  cb add $::c1
+  cb add $::c2
+} -test {
+  faultsim_test_result {0 SQLITE_OK} {1 SQLITE_NOMEM}
+  catch { cb delete }
+}
+
+
+finish_test
@@ -29,7 +29,7 @@ do_test 1.0 {
    WITH s(i) AS (
      VALUES(1) UNION ALL SELECT i+1 FROM s WHERe i<10000
    )
-    INSERT INTO t1 SELECT 'abcde', randomblob(16), i FROM s;
+    INSERT INTO t1 SELECT 'abcde', randomblob(18), i FROM s;
  }
  compare_db db db2
 } {}
@@ -0,0 +1,485 @@
+
+#if !defined(SQLITE_TEST) || (defined(SQLITE_ENABLE_SESSION) && defined(SQLITE_ENABLE_PREUPDATE_HOOK))
+
+#include "sqlite3session.h"
+#include "sqlite3changebatch.h"
+
+#include <assert.h>
+#include <string.h>
+
+typedef struct BatchTable BatchTable;
+typedef struct BatchIndex BatchIndex;
+typedef struct BatchIndexEntry BatchIndexEntry;
+typedef struct BatchHash BatchHash;
+
+struct sqlite3_changebatch {
+  sqlite3 *db;                    /* Database handle used to read schema */
+  BatchTable *pTab;               /* First in linked list of tables */
+  int iChangesetId;               /* Current changeset id */
+  int iNextIdxId;                 /* Next available index id */
+  int nEntry;                     /* Number of entries in hash table */
+  int nHash;                      /* Number of hash buckets */
+  BatchIndexEntry **apHash;       /* Array of hash buckets */
+};
+
+struct BatchTable {
+  BatchIndex *pIdx;               /* First in linked list of UNIQUE indexes */
+  BatchTable *pNext;              /* Next table */
+  char zTab[1];                   /* Table name */
+};
+
+struct BatchIndex {
+  BatchIndex *pNext;              /* Next index on same table */
+  int iId;                        /* Index id (assigned internally) */
+  int bPk;                        /* True for PK index */
+  int nCol;                       /* Size of aiCol[] array */
+  int *aiCol;                     /* Array of columns that make up index */
+};
+
+struct BatchIndexEntry {
+  BatchIndexEntry *pNext;         /* Next colliding hash table entry */
+  int iChangesetId;               /* Id of associated changeset */
+  int iIdxId;                     /* Id of index this key is from */
+  int szRecord;
+  char aRecord[1];
+};
+
+/*
+** Allocate and zero a block of nByte bytes. Must be freed using cbFree().
+*/
+static void *cbMalloc(int *pRc, int nByte){
+  void *pRet;
+
+  if( *pRc ){
+    pRet = 0;
+  }else{
+    pRet = sqlite3_malloc(nByte);
+    if( pRet ){
+      memset(pRet, 0, nByte);
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+
+  return pRet;
+}
+
+/*
+** Free an allocation made by cbMalloc().
+*/
+static void cbFree(void *p){
+  sqlite3_free(p);
+}
+
+/*
+** Return the hash bucket that pEntry belongs in.
+*/
+static int cbHash(sqlite3_changebatch *p, BatchIndexEntry *pEntry){
+  unsigned int iHash = (unsigned int)pEntry->iIdxId;
+  unsigned char *pEnd = (unsigned char*)&pEntry->aRecord[pEntry->szRecord];
+  unsigned char *pIter;
+
+  for(pIter=(unsigned char*)pEntry->aRecord; pIter<pEnd; pIter++){
+    iHash += (iHash << 7) + *pIter;
+  }
+
+  return (int)(iHash % p->nHash);
+}
+
+/*
+** Resize the hash table.
+*/
+static int cbHashResize(sqlite3_changebatch *p){
+  int rc = SQLITE_OK;
+  BatchIndexEntry **apNew;
+  int nNew = (p->nHash ? p->nHash*2 : 512);
+  int i;
+
+  apNew = cbMalloc(&rc, sizeof(BatchIndexEntry*) * nNew);
+  if( rc==SQLITE_OK ){
+    int nHash = p->nHash;
+    p->nHash = nNew;
+    for(i=0; i<nHash; i++){
+      BatchIndexEntry *pEntry;
+      while( (pEntry=p->apHash[i])!=0 ){
+        int iHash = cbHash(p, pEntry);
+        p->apHash[i] = pEntry->pNext;
+        pEntry->pNext = apNew[iHash];
+        apNew[iHash] = pEntry;
+      }
+    }
+
+    cbFree(p->apHash);
+    p->apHash = apNew;
+  }
+
+  return rc;
+}
+
+
+/*
+** Allocate a new sqlite3_changebatch object.
+*/
+int sqlite3changebatch_new(sqlite3 *db, sqlite3_changebatch **pp){
+  sqlite3_changebatch *pRet;
+  int rc = SQLITE_OK;
+  *pp = pRet = (sqlite3_changebatch*)cbMalloc(&rc, sizeof(sqlite3_changebatch));
+  if( pRet ){
+    pRet->db = db;
+  }
+  return rc;
+}
+
+/*
+** Add a BatchIndex entry for index zIdx to table pTab.
+*/
+static int cbAddIndex(
+  sqlite3_changebatch *p, 
+  BatchTable *pTab, 
+  const char *zIdx, 
+  int bPk
+){
+  int nCol = 0;
+  sqlite3_stmt *pIndexInfo = 0;
+  BatchIndex *pNew = 0;
+  int rc;
+  char *zIndexInfo;
+
+  zIndexInfo = (char*)sqlite3_mprintf("PRAGMA main.index_info = %Q", zIdx);
+  if( zIndexInfo ){
+    rc = sqlite3_prepare_v2(p->db, zIndexInfo, -1, &pIndexInfo, 0);
+    sqlite3_free(zIndexInfo);
+  }else{
+    rc = SQLITE_NOMEM;
+  }
+
+  if( rc==SQLITE_OK ){
+    while( SQLITE_ROW==sqlite3_step(pIndexInfo) ){ nCol++; }
+    rc = sqlite3_reset(pIndexInfo);
+  }
+
+  pNew = (BatchIndex*)cbMalloc(&rc, sizeof(BatchIndex) + sizeof(int) * nCol);
+  if( rc==SQLITE_OK ){
+    pNew->nCol = nCol;
+    pNew->bPk = bPk;
+    pNew->aiCol = (int*)&pNew[1];
+    pNew->iId = p->iNextIdxId++;
+    while( SQLITE_ROW==sqlite3_step(pIndexInfo) ){ 
+      int i = sqlite3_column_int(pIndexInfo, 0);
+      int j = sqlite3_column_int(pIndexInfo, 1);
+      pNew->aiCol[i] = j;
+    }
+    rc = sqlite3_reset(pIndexInfo);
+  }
+
+  if( rc==SQLITE_OK ){
+    pNew->pNext = pTab->pIdx;
+    pTab->pIdx = pNew;
+  }else{
+    cbFree(pNew);
+  }
+  sqlite3_finalize(pIndexInfo);
+
+  return rc;
+}
+
+/*
+** Free the object passed as the first argument.
+*/
+static void cbFreeTable(BatchTable *pTab){
+  BatchIndex *pIdx;
+  BatchIndex *pIdxNext;
+  for(pIdx=pTab->pIdx; pIdx; pIdx=pIdxNext){
+    pIdxNext = pIdx->pNext;
+    cbFree(pIdx);
+  }
+  cbFree(pTab);
+}
+
+/*
+** Find or create the BatchTable object named zTab.
+*/
+static int cbFindTable(
+  sqlite3_changebatch *p, 
+  const char *zTab, 
+  BatchTable **ppTab
+){
+  BatchTable *pRet = 0;
+  int rc = SQLITE_OK;
+
+  for(pRet=p->pTab; pRet; pRet=pRet->pNext){
+    if( 0==sqlite3_stricmp(zTab, pRet->zTab) ) break;
+  }
+
+  if( pRet==0 ){
+    int nTab = strlen(zTab);
+    pRet = (BatchTable*)cbMalloc(&rc, nTab + sizeof(BatchTable));
+    if( pRet ){
+      sqlite3_stmt *pIndexList = 0;
+      char *zIndexList = 0;
+      int rc2;
+      memcpy(pRet->zTab, zTab, nTab);
+
+      zIndexList = sqlite3_mprintf("PRAGMA main.index_list = %Q", zTab);
+      if( zIndexList==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        rc = sqlite3_prepare_v2(p->db, zIndexList, -1, &pIndexList, 0);
+        sqlite3_free(zIndexList);
+      }
+
+      while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pIndexList) ){
+        if( sqlite3_column_int(pIndexList, 2) ){
+          const char *zIdx = (const char*)sqlite3_column_text(pIndexList, 1);
+          const char *zTyp = (const char*)sqlite3_column_text(pIndexList, 3);
+          rc = cbAddIndex(p, pRet, zIdx, (zTyp[0]=='p'));
+        }
+      }
+      rc2 = sqlite3_finalize(pIndexList);
+      if( rc==SQLITE_OK ) rc = rc2;
+
+      if( rc==SQLITE_OK ){
+        pRet->pNext = p->pTab;
+        p->pTab = pRet;
+      }else{
+        cbFreeTable(pRet);
+        pRet = 0;
+      }
+    }
+  }
+
+  *ppTab = pRet;
+  return rc;
+}
+
+/*
+** Extract value iVal from the changeset iterator passed as the first
+** argument. Set *ppVal to point to the value before returning.
+**
+** This function attempts to extract the value using function xVal
+** (which is always either sqlite3changeset_new or sqlite3changeset_old).
+** If the call returns SQLITE_OK but does not supply an sqlite3_value*
+** pointer, an attempt to extract the value is made using the xFallback 
+** function.
+*/
+static int cbGetChangesetValue(
+  sqlite3_changeset_iter *pIter, 
+  int (*xVal)(sqlite3_changeset_iter*,int,sqlite3_value**),
+  int (*xFallback)(sqlite3_changeset_iter*,int,sqlite3_value**),
+  int iVal,
+  sqlite3_value **ppVal
+){
+  int rc = xVal(pIter, iVal, ppVal);
+  if( rc==SQLITE_OK && *ppVal==0 && xFallback ){
+    rc = xFallback(pIter, iVal, ppVal);
+  }
+  return rc;
+}
+
+static int cbAddToHash(
+  sqlite3_changebatch *p, 
+  sqlite3_changeset_iter *pIter, 
+  BatchIndex *pIdx, 
+  int (*xVal)(sqlite3_changeset_iter*,int,sqlite3_value**),
+  int (*xFallback)(sqlite3_changeset_iter*,int,sqlite3_value**),
+  int *pbConf
+){
+  BatchIndexEntry *pNew;
+  int sz = pIdx->nCol;
+  int i;
+  int iOut = 0;
+  int rc = SQLITE_OK;
+
+  for(i=0; rc==SQLITE_OK && i<pIdx->nCol; i++){
+    sqlite3_value *pVal;
+    rc = cbGetChangesetValue(pIter, xVal, xFallback, pIdx->aiCol[i], &pVal);
+    if( rc==SQLITE_OK ){
+      int eType = 0;
+      if( pVal ) eType = sqlite3_value_type(pVal);
+      switch( eType ){
+        case 0:
+        case SQLITE_NULL:
+          return SQLITE_OK;
+
+        case SQLITE_INTEGER:
+          sz += 8;
+          break;
+        case SQLITE_FLOAT:
+          sz += 8;
+          break;
+
+        default:
+          assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
+          sz += sqlite3_value_bytes(pVal);
+          break;
+      }
+    }
+  }
+
+  pNew = cbMalloc(&rc, sizeof(BatchIndexEntry) + sz);
+  if( pNew ){
+    pNew->iChangesetId = p->iChangesetId;
+    pNew->iIdxId = pIdx->iId;
+    pNew->szRecord = sz;
+
+    for(i=0; i<pIdx->nCol; i++){
+      int eType;
+      sqlite3_value *pVal;
+      rc = cbGetChangesetValue(pIter, xVal, xFallback, pIdx->aiCol[i], &pVal);
+      if( rc!=SQLITE_OK ) break;  /* coverage: condition is never true */
+      eType = sqlite3_value_type(pVal);
+      pNew->aRecord[iOut++] = eType;
+      switch( eType ){
+        case SQLITE_INTEGER: {
+          sqlite3_int64 i64 = sqlite3_value_int64(pVal);
+          memcpy(&pNew->aRecord[iOut], &i64, 8);
+          iOut += 8;
+          break;
+        }
+        case SQLITE_FLOAT: {
+          double d64 = sqlite3_value_double(pVal);
+          memcpy(&pNew->aRecord[iOut], &d64, sizeof(double));
+          iOut += sizeof(double);
+          break;
+        }
+
+        default: {
+          int nByte = sqlite3_value_bytes(pVal);
+          const char *z = (const char*)sqlite3_value_blob(pVal);
+          memcpy(&pNew->aRecord[iOut], z, nByte);
+          iOut += nByte;
+          break;
+        }
+      }
+    }
+  }
+
+  if( rc==SQLITE_OK && p->nEntry>=(p->nHash/2) ){
+    rc = cbHashResize(p);
+  }
+
+  if( rc==SQLITE_OK ){
+    BatchIndexEntry *pIter;
+    int iHash = cbHash(p, pNew);
+
+    assert( iHash>=0 && iHash<p->nHash );
+    for(pIter=p->apHash[iHash]; pIter; pIter=pIter->pNext){
+      if( pNew->szRecord==pIter->szRecord 
+       && 0==memcmp(pNew->aRecord, pIter->aRecord, pNew->szRecord)
+      ){
+        if( pNew->iChangesetId!=pIter->iChangesetId ){
+          *pbConf = 1;
+        }
+        cbFree(pNew);
+        pNew = 0;
+        break;
+      }
+    }
+
+    if( pNew ){
+      pNew->pNext = p->apHash[iHash];
+      p->apHash[iHash] = pNew;
+      p->nEntry++;
+    }
+  }else{
+    cbFree(pNew);
+  }
+
+  return rc;
+}
+
+
+/*
+** Add a changeset to the current batch.
+*/
+int sqlite3changebatch_add(sqlite3_changebatch *p, void *pBuf, int nBuf){
+  sqlite3_changeset_iter *pIter;  /* Iterator opened on pBuf/nBuf */
+  int rc;                         /* Return code */
+  int bConf = 0;                  /* Conflict was detected */
+
+  rc = sqlite3changeset_start(&pIter, nBuf, pBuf);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    for(rc2 = sqlite3changeset_next(pIter);
+        rc2==SQLITE_ROW;
+        rc2 = sqlite3changeset_next(pIter)
+    ){
+      BatchTable *pTab;
+      BatchIndex *pIdx;
+      const char *zTab;           /* Table this change applies to */
+      int nCol;                   /* Number of columns in table */
+      int op;                     /* UPDATE, INSERT or DELETE */
+
+      sqlite3changeset_op(pIter, &zTab, &nCol, &op, 0);
+      assert( op==SQLITE_INSERT || op==SQLITE_UPDATE || op==SQLITE_DELETE );
+
+      rc = cbFindTable(p, zTab, &pTab);
+      assert( pTab || rc!=SQLITE_OK );
+      if( pTab ){
+        for(pIdx=pTab->pIdx; pIdx && rc==SQLITE_OK; pIdx=pIdx->pNext){
+          if( op==SQLITE_UPDATE && pIdx->bPk ) continue;
+          if( op==SQLITE_UPDATE || op==SQLITE_DELETE ){
+            rc = cbAddToHash(p, pIter, pIdx, sqlite3changeset_old, 0, &bConf);
+          }
+          if( op==SQLITE_UPDATE || op==SQLITE_INSERT ){
+            rc = cbAddToHash(p, pIter, pIdx, 
+                sqlite3changeset_new, sqlite3changeset_old, &bConf
+            );
+          }
+        }
+      }
+      if( rc!=SQLITE_OK ) break;
+    }
+
+    rc2 = sqlite3changeset_finalize(pIter);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  if( rc==SQLITE_OK && bConf ){
+    rc = SQLITE_CONSTRAINT;
+  }
+  p->iChangesetId++;
+  return rc;
+}
+
+/*
+** Zero an existing changebatch object.
+*/
+void sqlite3changebatch_zero(sqlite3_changebatch *p){
+  int i;
+  for(i=0; i<p->nHash; i++){
+    BatchIndexEntry *pEntry;
+    BatchIndexEntry *pNext;
+    for(pEntry=p->apHash[i]; pEntry; pEntry=pNext){
+      pNext = pEntry->pNext;
+      cbFree(pEntry);
+    }
+  }
+  cbFree(p->apHash);
+  p->nHash = 0;
+  p->apHash = 0;
+}
+
+/*
+** Delete a changebatch object.
+*/
+void sqlite3changebatch_delete(sqlite3_changebatch *p){
+  BatchTable *pTab;
+  BatchTable *pTabNext;
+
+  sqlite3changebatch_zero(p);
+  for(pTab=p->pTab; pTab; pTab=pTabNext){
+    pTabNext = pTab->pNext;
+    cbFreeTable(pTab);
+  }
+  cbFree(p);
+}
+
+/*
+** Return the db handle.
+*/
+sqlite3 *sqlite3changebatch_db(sqlite3_changebatch *p){
+  return p->db;
+}
+
+#endif /* SQLITE_ENABLE_SESSION && SQLITE_ENABLE_PREUPDATE_HOOK */
@@ -0,0 +1,82 @@
+
+#if !defined(SQLITECHANGEBATCH_H_) 
+#define SQLITECHANGEBATCH_H_ 1
+
+typedef struct sqlite3_changebatch sqlite3_changebatch;
+
+/*
+** Create a new changebatch object for detecting conflicts between
+** changesets associated with a schema equivalent to that of the "main"
+** database of the open database handle db passed as the first
+** parameter. It is the responsibility of the caller to ensure that
+** the database handle is not closed until after the changebatch
+** object has been deleted.
+**
+** A changebatch object is used to detect batches of non-conflicting
+** changesets. Changesets that do not conflict may be applied to the 
+** target database in any order without affecting the final state of 
+** the database.
+**
+** The changebatch object only works reliably if PRIMARY KEY and UNIQUE
+** constraints on tables affected by the changesets use collation
+** sequences that are equivalent to built-in collation sequence 
+** BINARY for the == operation.
+**
+** If successful, SQLITE_OK is returned and (*pp) set to point to
+** the new changebatch object. If an error occurs, an SQLite error
+** code is returned and the final value of (*pp) is undefined.
+*/
+int sqlite3changebatch_new(sqlite3 *db, sqlite3_changebatch **pp);
+
+/*
+** Argument p points to a buffer containing a changeset n bytes in
+** size. Assuming no error occurs, this function returns SQLITE_OK
+** if the changeset does not conflict with any changeset passed 
+** to an sqlite3changebatch_add() call made on the same 
+** sqlite3_changebatch* handle since the most recent call to
+** sqlite3changebatch_zero(). If the changeset does conflict with 
+** an earlier such changeset, SQLITE_CONSTRAINT is returned. Or, 
+** if an error occurs, some other SQLite error code may be returned.
+**
+** One changeset is said to conflict with another if
+** either:
+**
+**   * the two changesets contain operations (INSERT, UPDATE or 
+**     DELETE) on the same row, identified by primary key, or
+**
+**   * the two changesets contain operations (INSERT, UPDATE or 
+**     DELETE) on rows with identical values in any combination 
+**     of fields constrained by a UNIQUE constraint.
+**
+** Even if this function returns SQLITE_CONFLICT, the current
+** changeset is added to the internal data structures - so future
+** calls to this function may conflict with it. If this function
+** returns any result code other than SQLITE_OK or SQLITE_CONFLICT,
+** the result of any future call to sqlite3changebatch_add() is
+** undefined.
+**
+** Only changesets may be passed to this function. Passing a 
+** patchset to this function results in an SQLITE_MISUSE error.
+*/
+int sqlite3changebatch_add(sqlite3_changebatch*, void *p, int n);
+
+/*
+** Zero a changebatch object. This causes the records of all earlier 
+** calls to sqlite3changebatch_add() to be discarded.
+*/
+void sqlite3changebatch_zero(sqlite3_changebatch*);
+
+/*
+** Return a copy of the first argument passed to the sqlite3changebatch_new()
+** call used to create the changebatch object passed as the only argument
+** to this function.
+*/
+sqlite3 *sqlite3changebatch_db(sqlite3_changebatch*);
+
+/*
+** Delete a changebatch object.
+*/
+void sqlite3changebatch_delete(sqlite3_changebatch*);
+
+#endif /* !defined(SQLITECHANGEBATCH_H_) */
+
@@ -25,6 +25,13 @@ typedef struct SessionInput SessionInput;
 # endif
 #endif

+/*
+** The three different types of changesets generated.
+*/
+#define SESSIONS_PATCHSET      0
+#define SESSIONS_CHANGESET     1
+#define SESSIONS_FULLCHANGESET 2
+
 static int sessions_strm_chunk_size = SESSIONS_STRM_CHUNK_SIZE;

 typedef struct SessionHook SessionHook;
@@ -2233,7 +2240,7 @@ static void sessionAppendCol(
 */ 
 static int sessionAppendUpdate(
  SessionBuffer *pBuf,            /* Buffer to append to */
-  int bPatchset,                  /* True for "patchset", 0 for "changeset" */
+  int ePatchset,                  /* True for "patchset", 0 for "changeset" */
  sqlite3_stmt *pStmt,            /* Statement handle pointing at new row */
  SessionChange *p,               /* Object containing old values */
  u8 *abPK                        /* Boolean array - true for PK columns */
@@ -2297,8 +2304,8 @@ static int sessionAppendUpdate(

    /* Add a field to the old.* record. This is omitted if this modules is
    ** currently generating a patchset. */
-    if( bPatchset==0 ){
-      if( bChanged || abPK[i] ){
+    if( ePatchset!=SESSIONS_PATCHSET ){
+      if( ePatchset==SESSIONS_FULLCHANGESET || bChanged || abPK[i] ){
        sessionAppendBlob(pBuf, pCsr, nAdvance, &rc);
      }else{
        sessionAppendByte(pBuf, 0, &rc);
@@ -2307,7 +2314,7 @@ static int sessionAppendUpdate(

    /* Add a field to the new.* record. Or the only record if currently
    ** generating a patchset.  */
-    if( bChanged || (bPatchset && abPK[i]) ){
+    if( bChanged || (ePatchset==SESSIONS_PATCHSET && abPK[i]) ){
      sessionAppendCol(&buf2, pStmt, i, &rc);
    }else{
      sessionAppendByte(&buf2, 0, &rc);
@@ -2333,7 +2340,7 @@ static int sessionAppendUpdate(
 */
 static int sessionAppendDelete(
  SessionBuffer *pBuf,            /* Buffer to append to */
-  int bPatchset,                  /* True for "patchset", 0 for "changeset" */
+  int eChangeset,                 /* One of SESSIONS_CHANGESET etc. */
  SessionChange *p,               /* Object containing old values */
  int nCol,                       /* Number of columns in table */
  u8 *abPK                        /* Boolean array - true for PK columns */
@@ -2343,7 +2350,7 @@ static int sessionAppendDelete(
  sessionAppendByte(pBuf, SQLITE_DELETE, &rc);
  sessionAppendByte(pBuf, p->bIndirect, &rc);

-  if( bPatchset==0 ){
+  if( eChangeset!=SESSIONS_PATCHSET ){
    sessionAppendBlob(pBuf, p->aRecord, p->nRecord, &rc);
  }else{
    int i;
@@ -2516,12 +2523,12 @@ static int sessionSelectBind(
 */
 static void sessionAppendTableHdr(
  SessionBuffer *pBuf,            /* Append header to this buffer */
-  int bPatchset,                  /* Use the patchset format if true */
+  int ePatchset,                  /* Use the patchset format if true */
  SessionTable *pTab,             /* Table object to append header for */
  int *pRc                        /* IN/OUT: Error code */
 ){
  /* Write a table header */
-  sessionAppendByte(pBuf, (bPatchset ? 'P' : 'T'), pRc);
+  sessionAppendByte(pBuf, (ePatchset==SESSIONS_PATCHSET) ? 'P' : 'T', pRc);
  sessionAppendVarint(pBuf, pTab->nCol, pRc);
  sessionAppendBlob(pBuf, pTab->abPK, pTab->nCol, pRc);
  sessionAppendBlob(pBuf, (u8 *)pTab->zName, (int)strlen(pTab->zName)+1, pRc);
@@ -2539,7 +2546,7 @@ static void sessionAppendTableHdr(
 */
 static int sessionGenerateChangeset(
  sqlite3_session *pSession,      /* Session object */
-  int bPatchset,                  /* True for patchset, false for changeset */
+  int ePatchset,                  /* One of SESSIONS_CHANGESET etc. */
  int (*xOutput)(void *pOut, const void *pData, int nData),
  void *pOut,                     /* First argument for xOutput */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
@@ -2586,7 +2593,7 @@ static int sessionGenerateChangeset(
      }

      /* Write a table header */
-      sessionAppendTableHdr(&buf, bPatchset, pTab, &rc);
+      sessionAppendTableHdr(&buf, ePatchset, pTab, &rc);

      /* Build and compile a statement to execute: */
      if( rc==SQLITE_OK ){
@@ -2611,10 +2618,10 @@ static int sessionGenerateChangeset(
              }
            }else{
              assert( abPK!=0 );  /* Because sessionSelectStmt() returned ok */
-              rc = sessionAppendUpdate(&buf, bPatchset, pSel, p, abPK);
+              rc = sessionAppendUpdate(&buf, ePatchset, pSel, p, abPK);
            }
          }else if( p->op!=SQLITE_INSERT ){
-            rc = sessionAppendDelete(&buf, bPatchset, p, nCol, abPK);
+            rc = sessionAppendDelete(&buf, ePatchset, p, nCol, abPK);
          }
          if( rc==SQLITE_OK ){
            rc = sqlite3_reset(pSel);
@@ -2674,7 +2681,8 @@ int sqlite3session_changeset(
  int rc;

  if( pnChangeset==0 || ppChangeset==0 ) return SQLITE_MISUSE;
-  rc = sessionGenerateChangeset(pSession, 0, 0, 0, pnChangeset,ppChangeset);
+  rc = sessionGenerateChangeset(
+      pSession, SESSIONS_CHANGESET, 0, 0, pnChangeset, ppChangeset);
  assert( rc || pnChangeset==0 
       || pSession->bEnableSize==0 || *pnChangeset<=pSession->nMaxChangesetSize 
  );
@@ -2690,7 +2698,8 @@ int sqlite3session_changeset_strm(
  void *pOut
 ){
  if( xOutput==0 ) return SQLITE_MISUSE;
-  return sessionGenerateChangeset(pSession, 0, xOutput, pOut, 0, 0);
+  return sessionGenerateChangeset(
+      pSession, SESSIONS_CHANGESET, xOutput, pOut, 0, 0);
 }

 /*
@@ -2702,7 +2711,8 @@ int sqlite3session_patchset_strm(
  void *pOut
 ){
  if( xOutput==0 ) return SQLITE_MISUSE;
-  return sessionGenerateChangeset(pSession, 1, xOutput, pOut, 0, 0);
+  return sessionGenerateChangeset(
+      pSession, SESSIONS_PATCHSET, xOutput, pOut, 0, 0);
 }

 /*
@@ -2718,9 +2728,20 @@ int sqlite3session_patchset(
  void **ppPatchset               /* OUT: Buffer containing changeset */
 ){
  if( pnPatchset==0 || ppPatchset==0 ) return SQLITE_MISUSE;
-  return sessionGenerateChangeset(pSession, 1, 0, 0, pnPatchset, ppPatchset);
+  return sessionGenerateChangeset(
+      pSession, SESSIONS_PATCHSET, 0, 0, pnPatchset, ppPatchset);
 }

+int sqlite3session_fullchangeset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+){
+  return sessionGenerateChangeset(
+      pSession, SESSIONS_FULLCHANGESET, 0, 0, pnChangeset, ppChangeset);
+}
+
+
 /*
 ** Enable or disable the session object passed as the first argument.
 */
@@ -5263,10 +5284,11 @@ static int sessionChangegroupOutput(
  ** hash tables attached to the SessionTable objects in list p->pList. 
  */
  for(pTab=pGrp->pList; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
+    int eChangeset = pGrp->bPatch ? SESSIONS_PATCHSET : SESSIONS_CHANGESET;
    int i;
    if( pTab->nEntry==0 ) continue;

-    sessionAppendTableHdr(&buf, pGrp->bPatch, pTab, &rc);
+    sessionAppendTableHdr(&buf, eChangeset, pTab, &rc);
    for(i=0; i<pTab->nChange; i++){
      SessionChange *p;
      for(p=pTab->apChange[i]; p; p=p->pNext){
@@ -355,6 +355,19 @@ int sqlite3session_changeset(
  void **ppChangeset              /* OUT: Buffer containing changeset */
 );

+/*
+** CAPI3REF: Generate A Full Changeset From A Session Object
+**
+** This function is similar to sqlite3session_changeset(), except that for
+** each row affected by an UPDATE statement, all old.* values are recorded
+** as part of the changeset, not just those modified.
+*/
+int sqlite3session_fullchangeset(
+  sqlite3_session *pSession,      /* Session object */
+  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
+  void **ppChangeset              /* OUT: Buffer containing changeset */
+);
+
 /*
 ** CAPI3REF: Return An Upper-limit For The Size Of The Changeset
 ** METHOD: sqlite3_session
@@ -221,6 +221,7 @@ static int testStreamOutput(
 **          $session indirect INTEGER
 **          $session patchset
 **          $session table_filter SCRIPT
+**          $session fullchangeset
 */
 static int SQLITE_TCLAPI test_session_cmd(
  void *clientData,
@@ -234,20 +235,20 @@ static int SQLITE_TCLAPI test_session_cmd(
    const char *zSub;
    int nArg;
    const char *zMsg;
-    int iSub;
  } aSub[] = {
-    { "attach",       1, "TABLE",      }, /* 0 */
-    { "changeset",    0, "",           }, /* 1 */
-    { "delete",       0, "",           }, /* 2 */
-    { "enable",       1, "BOOL",       }, /* 3 */
-    { "indirect",     1, "BOOL",       }, /* 4 */
-    { "isempty",      0, "",           }, /* 5 */
-    { "table_filter", 1, "SCRIPT",     }, /* 6 */
+    { "attach",       1, "TABLE"       }, /* 0 */
+    { "changeset",    0, ""            }, /* 1 */
+    { "delete",       0, ""            }, /* 2 */
+    { "enable",       1, "BOOL"        }, /* 3 */
+    { "indirect",     1, "BOOL"        }, /* 4 */
+    { "isempty",      0, ""            }, /* 5 */
+    { "table_filter", 1, "SCRIPT"      }, /* 6 */
    { "patchset",     0, "",           }, /* 7 */
-    { "diff",         2, "FROMDB TBL", }, /* 8 */
-    { "memory_used",  0, "",           }, /* 9 */
-    { "changeset_size", 0, "",         }, /* 10 */
-    { "object_config_size", 1, "INTEGER", }, /* 11 */
+    { "diff",         2, "FROMDB TBL"  }, /* 8 */
+    { "fullchangeset",0, ""            }, /* 9 */
+    { "memory_used",  0, "",           }, /* 10 */
+    { "changeset_size", 0, "",         }, /* 11 */
+    { "object_config_size", 1, "INTEGER", }, /* 12 */
    { 0 }
  };
  int iSub;
@@ -277,10 +278,11 @@ static int SQLITE_TCLAPI test_session_cmd(
      break;
    }

+    case 9:        /* fullchangeset */
    case 7:        /* patchset */
    case 1: {      /* changeset */
      TestSessionsBlob o = {0, 0};
-      if( test_tcl_integer(interp, SESSION_STREAM_TCL_VAR) ){
+      if( iSub!=9 && test_tcl_integer(interp, SESSION_STREAM_TCL_VAR) ){
        void *pCtx = (void*)&o;
        if( iSub==7 ){
          rc = sqlite3session_patchset_strm(pSession, testStreamOutput, pCtx);
@@ -290,6 +292,8 @@ static int SQLITE_TCLAPI test_session_cmd(
      }else{
        if( iSub==7 ){
          rc = sqlite3session_patchset(pSession, &o.n, &o.p);
+        }else if( iSub==9 ){
+          rc = sqlite3session_fullchangeset(pSession, &o.n, &o.p);
        }else{
          rc = sqlite3session_changeset(pSession, &o.n, &o.p);
        }
@@ -304,6 +308,7 @@ static int SQLITE_TCLAPI test_session_cmd(
      break;
    }

+
    case 2:        /* delete */
      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
      break;
@@ -354,18 +359,18 @@ static int SQLITE_TCLAPI test_session_cmd(
      break;
    }

-    case 9: {      /* memory_used */
+    case 10: {      /* memory_used */
      sqlite3_int64 nMalloc = sqlite3session_memory_used(pSession);
      Tcl_SetObjResult(interp, Tcl_NewWideIntObj(nMalloc));
      break;
    }

-    case 10: {
+    case 11: {
      sqlite3_int64 nSize = sqlite3session_changeset_size(pSession);
      Tcl_SetObjResult(interp, Tcl_NewWideIntObj(nSize));
      break;
    }
-    case 11: {
+    case 12: {
      int rc;
      int iArg;
      if( Tcl_GetIntFromObj(interp, objv[2], &iArg) ){
@@ -521,7 +526,7 @@ static int test_filter_handler(

  Tcl_DecrRefCount(pEval);
  return res;
-}  
+}

 static int test_conflict_handler(
  void *pCtx,                     /* Pointer to TestConflictHandler structure */
@@ -1163,6 +1168,127 @@ static int SQLITE_TCLAPI test_sqlite3session_foreach(
  return TCL_OK;
 }

+#include "sqlite3changebatch.h"
+
+typedef struct TestChangebatch TestChangebatch;
+struct TestChangebatch {
+  sqlite3_changebatch *pChangebatch;
+};
+
+/*
+** Tclcmd:  $changebatch add BLOB
+**          $changebatch zero
+**          $changebatch delete
+*/
+static int SQLITE_TCLAPI test_changebatch_cmd(
+  void *clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  TestChangebatch *p = (TestChangebatch*)clientData;
+  sqlite3_changebatch *pChangebatch = p->pChangebatch;
+  struct SessionSubcmd {
+    const char *zSub;
+    int nArg;
+    const char *zMsg;
+    int iSub;
+  } aSub[] = {
+    { "add",          1, "CHANGESET",  }, /* 0 */
+    { "zero",         0, "",           }, /* 1 */
+    { "delete",       0, "",           }, /* 2 */
+    { 0 }
+  };
+  int iSub;
+  int rc;
+
+  if( objc<2 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
+    return TCL_ERROR;
+  }
+  rc = Tcl_GetIndexFromObjStruct(interp, 
+      objv[1], aSub, sizeof(aSub[0]), "sub-command", 0, &iSub
+  );
+  if( rc!=TCL_OK ) return rc;
+  if( objc!=2+aSub[iSub].nArg ){
+    Tcl_WrongNumArgs(interp, 2, objv, aSub[iSub].zMsg);
+    return TCL_ERROR;
+  }
+
+  switch( iSub ){
+    case 0: {      /* add */
+      int nArg;
+      unsigned char *pArg = Tcl_GetByteArrayFromObj(objv[2], &nArg);
+      rc = sqlite3changebatch_add(pChangebatch, pArg, nArg);
+      if( rc!=SQLITE_OK && rc!=SQLITE_CONSTRAINT ){
+        return test_session_error(interp, rc, 0);
+      }else{
+        extern const char *sqlite3ErrName(int);
+        Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+      }
+      break;
+    }
+
+    case 1: {      /* zero */
+      sqlite3changebatch_zero(pChangebatch);
+      break;
+    }
+
+    case 2:        /* delete */
+      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
+      break;
+  }
+
+  return TCL_OK;
+}
+
+static void SQLITE_TCLAPI test_changebatch_del(void *clientData){
+  TestChangebatch *p = (TestChangebatch*)clientData;
+  sqlite3changebatch_delete(p->pChangebatch);
+  ckfree((char*)p);
+}
+
+/*
+** Tclcmd:  sqlite3changebatch CMD DB-HANDLE
+*/
+static int SQLITE_TCLAPI test_sqlite3changebatch(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  sqlite3 *db;
+  Tcl_CmdInfo info;
+  int rc;                         /* sqlite3session_create() return code */
+  TestChangebatch *p;             /* New wrapper object */
+
+  if( objc!=3 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "CMD DB-HANDLE");
+    return TCL_ERROR;
+  }
+
+  if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(objv[2]), &info) ){
+    Tcl_AppendResult(interp, "no such handle: ", Tcl_GetString(objv[2]), 0);
+    return TCL_ERROR;
+  }
+  db = *(sqlite3 **)info.objClientData;
+
+  p = (TestChangebatch*)ckalloc(sizeof(TestChangebatch));
+  memset(p, 0, sizeof(TestChangebatch));
+  rc = sqlite3changebatch_new(db, &p->pChangebatch);
+  if( rc!=SQLITE_OK ){
+    ckfree((char*)p);
+    return test_session_error(interp, rc, 0);
+  }
+
+  Tcl_CreateObjCommand(
+      interp, Tcl_GetString(objv[1]), test_changebatch_cmd, (ClientData)p,
+      test_changebatch_del
+  );
+  Tcl_SetObjResult(interp, objv[1]);
+  return TCL_OK;
+}
+
 /*
 ** tclcmd: CMD configure REBASE-BLOB
 ** tclcmd: CMD rebase CHANGESET
@@ -1345,6 +1471,10 @@ int TestSession_Init(Tcl_Interp *interp){
    Tcl_CreateObjCommand(interp, p->zCmd, p->xProc, 0, 0);
  }

+
+  Tcl_CreateObjCommand(
+      interp, "sqlite3changebatch", test_sqlite3changebatch, 0, 0
+  );
  return TCL_OK;
 }

@@ -423,6 +423,7 @@ TESTSRC2 = \
  $(TOP)/src/select.c \
  $(TOP)/src/threads.c \
  $(TOP)/src/tokenize.c \
+  $(TOP)/src/treeview.c \
  $(TOP)/src/utf.c \
  $(TOP)/src/util.c \
  $(TOP)/src/vdbeapi.c \
@@ -442,6 +443,7 @@ TESTSRC2 = \
  $(TOP)/ext/async/sqlite3async.c \
  $(TOP)/ext/misc/stmt.c \
  $(TOP)/ext/session/sqlite3session.c \
+  $(TOP)/ext/session/sqlite3changebatch.c \
  $(TOP)/ext/session/test_session.c \
  fts5.c

@@ -998,6 +1000,9 @@ THREADTEST3_SRC = $(TOP)/test/threadtest3.c    \
 threadtest3$(EXE): sqlite3.o $(THREADTEST3_SRC) $(TOP)/src/test_multiplex.c
 	$(TCCX) $(TOP)/test/threadtest3.c $(TOP)/src/test_multiplex.c sqlite3.o -o $@ $(THREADLIB)

+bc_test1$(EXE): sqlite3.o $(TOP)/test/bc_test1.c $(TOP)/test/tt3_core.c
+	$(TCCX) $(TOP)/test/bc_test1.c sqlite3.o -o $@ $(THREADLIB)
+
 threadtest: threadtest3$(EXE)
 	./threadtest3$(EXE)

@@ -1,13 +1,13 @@
-C Version\s3.39.0
-D 2022-06-25T14:57:57.276
+C Version\s3.39.3\spatches\sapplied\sto\sthe\sbegin-concurrent\sbranch.
+D 2022-09-05T12:39:06.361
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
-F Makefile.in bccb0ed3f05fc41aee15da77c844c48b5da419cbb9af35b8a147536c9ad1c822
+F Makefile.in 21c3063046056bac86a5b0c5c6ccd0bcafa2b126233b48b8fc3789528a0e14e9
 F Makefile.linux-gcc f609543700659711fbd230eced1f01353117621dccae7b9fb70daa64236c5241
 F Makefile.msc de7cb3e095ce2fdc33513ccd76ebdaeda1483d0ddab0410fe65cbdeadd4c0ee1
 F README.md 8b8df9ca852aeac4864eb1e400002633ee6db84065bd01b78c33817f97d31f5e
-F VERSION fa8e7d2d1cc962f9e14c6d410387cf75860ee139462763fda887c1be4261f824
+F VERSION 44ff0193e2e50e452ced9e0d671d85d52b7ef48e555d4ee5e96574c5e6a9e3b7
 F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
 F art/sqlite370.eps aa97a671332b432a54e1d74ff5e8775be34200c2
 F art/sqlite370.ico af56c1d00fee7cd4753e8631ed60703ed0fc6e90
@@ -34,10 +34,11 @@ F autoconf/tea/win/rules.vc c511f222b80064096b705dbeb97060ee1d6b6d63
 F config.guess 883205ddf25b46f10c181818bf42c09da9888884af96f79e1719264345053bd6
 F config.h.in 6376abec766e9a0785178b1823b5a587e9f1ccbc
 F config.sub c2d0260f17f3e4bc0b6808fccf1b291cb5e9126c14fc5890efc77b9fd0175559
-F configure 00378d14cca0ce02fa9eca28fd494789c2eda7d10d86003a5f9a42f34b0af418 x
+F configure db90011c341bf24afacc0b9957757c67a9db58e9ee7a34f265be1b9dc56c75da x
 F configure.ac 3ef6eeff4387585bfcab76b0c3f6e15a0618587bb90245dd5d44e4378141bb35
 F contrib/sqlitecon.tcl 210a913ad63f9f991070821e599d600bd913e0ad
 F doc/F2FS.txt c1d4a0ae9711cfe0e1d8b019d154f1c29e0d3abfe820787ba1e9ed7691160fcd
+F doc/begin_concurrent.md e694a2a1c623833e7de8b688e81ec30fd4439a78d6b74be61bce0b1e8f590470
 F doc/json-enhancements.md e356fc834781f1f1aa22ee300027a270b2c960122468499bf347bb123ce1ea4f
 F doc/lemon.html efc0cd2345d66905505d98f862e1c571512def0ceb5b016cb658fd4918eb76a3
 F doc/pager-invariants.txt 27fed9a70ddad2088750c4a2b493b63853da2710
@@ -102,7 +103,7 @@ F ext/fts3/README.content b9078d0843a094d86af0d48dffbff13c906702b4c3558012e67b9c
 F ext/fts3/README.syntax a19711dc5458c20734b8e485e75fb1981ec2427a
 F ext/fts3/README.tokenizers b92bdeb8b46503f0dd301d364efc5ef59ef9fa8e2758b8e742f39fa93a2e422d
 F ext/fts3/README.txt 8c18f41574404623b76917b9da66fcb0ab38328d
-F ext/fts3/fts3.c 6634a3854e70afa8710ee5e3a7253cd0f0c89d4cce207fcbfe2ead3bad1db7d5
+F ext/fts3/fts3.c b20bd583991e740c1e14371896f3ab61d7b6c033740646366bbf6667191bc4e2
 F ext/fts3/fts3.h 3a10a0af180d502cecc50df77b1b22df142817fe
 F ext/fts3/fts3Int.h dafdc371f9fbab175744b06cfe019d5f040cdfdbd11fea752f5dc28d45b04c05
 F ext/fts3/fts3_aux.c f0dc9bd98582615b7750218899bd0c729879b6bbf94d1be57ca1833ff49afc6f
@@ -191,7 +192,7 @@ F ext/fts5/test/fts5eb.test a973baadac524dbbb4ad9b0e99030e12cabde2c6b28e0ac43729
 F ext/fts5/test/fts5fault1.test d28a65caee75db6897c3cf1358c5230d3bb2a3bf7fb31062c19c7e5382b3d2bd
 F ext/fts5/test/fts5fault2.test 69c8fdbef830cd0d450908d4504d5bb86609e255af99c421c20a0756251fe344
 F ext/fts5/test/fts5fault3.test da2f9e3e56ff5740d68ebdd6877c97089e7ed28ddff28a0da87a6afea27e5522
-F ext/fts5/test/fts5fault4.test 1c1db5fcfe59401e7833146100f1d8de284a0a686fac31ddac9fb56c459f725b
+F ext/fts5/test/fts5fault4.test 87a10d0caee57da587c7588b0c8d25d2930197399b4812ad1e4d574c75324cee
 F ext/fts5/test/fts5fault5.test a336e4e11847de24c9497f80cce18e00bb3fab7fb11f97d04eb9af898900a762
 F ext/fts5/test/fts5fault6.test a0fc0a8f99e4b16500c31dfc7e38e1defe0f1693ac47650517ac7b723b1956f8
 F ext/fts5/test/fts5fault7.test 0acbec416edb24b8881f154e99c31e9ccf73f539cfcd164090be139e9e97ed4c
@@ -334,7 +335,7 @@ F ext/misc/normalize.c bd84355c118e297522aba74de34a4fd286fc775524e0499b14473918d
 F ext/misc/percentile.c b9086e223d583bdaf8cb73c98a6539d501a2fc4282654adbfea576453d82e691
 F ext/misc/prefixes.c 0f4f8cff5aebc00a7e3ac4021fd59cfe1a8e17c800ceaf592859ecb9cbc38196
 F ext/misc/qpvtab.c 09738419e25f603a35c0ac8bd0a04daab794f48d08a9bc07a6085b9057b99009
-F ext/misc/regexp.c b267fd05ff8d38b22f4c2809d7b7a2c61d522e9faf2feb928dbb9662e4a3a386
+F ext/misc/regexp.c 03e483711534c437b2e29648d2a4b7730f5cb781a434ac8150907376bc4489f6
 F ext/misc/remember.c add730f0f7e7436cd15ea3fd6a90fd83c3f706ab44169f7f048438b7d6baa69c
 F ext/misc/rot13.c 51ac5f51e9d5fd811db58a9c23c628ad5f333c173f1fc53c8491a3603d38556c
 F ext/misc/scrub.c 2a44b0d44c69584c0580ad2553f6290a307a49df4668941d2812135bfb96a946
@@ -344,7 +345,7 @@ F ext/misc/shathree.c 7b17615869a495659f1569ada1d8d3d21b4a24614f2746d93cc87ef7c0
 F ext/misc/showauth.c 732578f0fe4ce42d577e1c86dc89dd14a006ab52
 F ext/misc/spellfix.c 94df9bbfa514a563c1484f684a2df3d128a2f7209a84ca3ca100c68a0163e29f
 F ext/misc/sqlar.c 0ace5d3c10fe736dc584bf1159a36b8e2e60fab309d310cd8a0eecd9036621b6
-F ext/misc/stmt.c 35063044a388ead95557e4b84b89c1b93accc2f1c6ddea3f9710e8486a7af94a
+F ext/misc/stmt.c ed05ad78013edccd43f4fc33d8244001f6f886eb2dfd2106ba33616ac514c6fb
 F ext/misc/templatevtab.c 8a16a91a5ceaccfcbd6aaaa56d46828806e460dd194965b3f77bf38f14b942c4
 F ext/misc/totype.c fa4aedeb07f66169005dffa8de3b0a2b621779fd44f85c103228a42afa71853b
 F ext/misc/uint.c 053fed3bce2e89583afcd4bf804d75d659879bbcedac74d0fa9ed548839a030b
@@ -413,12 +414,12 @@ F ext/repair/test/checkfreelist01.test 3e8aa6aeb4007680c94a8d07b41c339aa635cc782
 F ext/repair/test/checkindex01.test b530f141413b587c9eb78ff734de6bb79bc3515c335096108c12c01bddbadcec
 F ext/repair/test/test.tcl 686d76d888dffd021f64260abf29a55c57b2cedfa7fc69150b42b1d6119aac3c
 F ext/rtree/README 6315c0d73ebf0ec40dedb5aa0e942bc8b54e3761
-F ext/rtree/geopoly.c cc3f89c11abcf114fa60d74709ae8b5bc1eae5a261b30bc1bb7085089c03bfab
+F ext/rtree/geopoly.c bb0dcd013dbb3fe0335b6bbae0d9c29fcfffda93d5ef6c31daa47e802132e435
 F ext/rtree/rtree.c d7b4b8b81d8d54376a7f81de5be85ec58b37c11604bcf42984a8418b34158d93
 F ext/rtree/rtree.h 4a690463901cb5e6127cf05eb8e642f127012fd5003830dbc974eca5802d9412
 F ext/rtree/rtree1.test d47f58832145fcfed9067bc457ca8664962196c4566c17a1ebd679367db55d11
 F ext/rtree/rtree2.test 9d9deddbb16fd0c30c36e6b4fdc3ee3132d765567f0f9432ee71e1303d32603d
-F ext/rtree/rtree3.test 4ee5d7df86040efe3d8d84f141f2962a7745452200a7cba1db06f86d97050499
+F ext/rtree/rtree3.test 272594f88c344e973864008bbe4c71fd3a41a264c097d568593ee7886d83d409
 F ext/rtree/rtree4.test 304de65d484540111b896827e4261815e5dca4ce28eeecd58be648cd73452c4b
 F ext/rtree/rtree5.test 49c9041d713d54560b315c2c7ef7207ee287eba1b20f8266968a06f2e55d3142
 F ext/rtree/rtree6.test 9ce3691c1aac43070a9f194f0ebf54372db346c5a82241fd11b525ed53ce9f3f
@@ -449,6 +450,8 @@ F ext/rtree/tkt3363.test 142ab96eded44a3615ec79fba98c7bde7d0f96de
 F ext/rtree/util/randomshape.tcl 54ee03d0d4a1c621806f7f44d5b78d2db8fac26e0e8687c36c4bd0203b27dbff
 F ext/rtree/viewrtree.tcl eea6224b3553599ae665b239bd827e182b466024
 F ext/rtree/visual01.txt e9c2564083bcd30ec51b07f881bffbf0e12b50a3f6fced0c222c5c1d2f94ac66
+F ext/session/changebatch1.test 9ceaa8f7b2a505933e250fbe6cbc550e4ce1e59d
+F ext/session/changebatchfault.test be49c793219bf387ad692a60856b921f0854ad6d
 F ext/session/changeset.c 7a1e6a14c7e92d36ca177e92e88b5281acd709f3b726298dc34ec0fb58869cb5
 F ext/session/changesetfuzz.c 227076ab0ae4447d742c01ee88a564da6478bbf26b65108bf8fac9cd8b0b24aa
 F ext/session/changesetfuzz1.test 2e1b90d888fbf0eea5e1bd2f1e527a48cc85f8e0ff75df1ec4e320b21f580b3a
@@ -467,7 +470,7 @@ F ext/session/sessionD.test 4f91d0ca8afc4c3969c72c9f0b5ea9527e21de29039937d0d973
 F ext/session/sessionE.test b2010949c9d7415306f64e3c2072ddabc4b8250c98478d3c0c4d064bce83111d
 F ext/session/sessionF.test d37ed800881e742c208df443537bf29aa49fd56eac520d0f0c6df3e6320f3401
 F ext/session/sessionG.test 3828b944cd1285f4379340fd36f8b64c464fc84df6ff3ccbc95578fd87140b9c
-F ext/session/sessionH.test b17afdbd3b8f17e9bab91e235acf167cf35485db2ab2df0ea8893fbb914741a4
+F ext/session/sessionH.test ecabc041e04e48671a94cd7c02993bc73f75dced943280a026e89cdf64374eef
 F ext/session/session_common.tcl f613174665456b2d916ae8df3e5735092a1c1712f36f46840172e9a01e8cc53e
 F ext/session/session_speed_test.c dcf0ef58d76b70c8fbd9eab3be77cf9deb8bc1638fed8be518b62d6cbdef88b3
 F ext/session/sessionat.test 52993535f1230a42f70886643574ba7ae60ef854f8add9c8e3fcc3eb5c564bd2
@@ -482,16 +485,18 @@ F ext/session/sessionrebase.test ccfa716b23bd1d3b03217ee58cfd90c78d4b99f53e6a9a2
 F ext/session/sessionsize.test 6f644aff31c7f1e4871e9ff3542766e18da68fc7e587b83a347ea9820a002dd8
 F ext/session/sessionstat1.test 218d351cf9fcd6648f125a26b607b140310160184723c2666091b54450a68fb5
 F ext/session/sessionwor.test 6fd9a2256442cebde5b2284936ae9e0d54bde692d0f5fd009ecef8511f4cf3fc
-F ext/session/sqlite3session.c 1d019c5caf51936ef24c761db63552b06e0e0d951c8740bba9639b17fa0cb107
-F ext/session/sqlite3session.h 0907de79bc13a2e3af30a6dc29acc60792a3eaf7d33d44cf52500d0f3c2b2171
-F ext/session/test_session.c f433f68a8a8c64b0f5bc74dc725078f12483301ad4ae8375205eef790274a787
+F ext/session/sqlite3changebatch.c d5553b79e012ee2cb06c0a96bdf9dfe19e66354390ea0036cc46c4953142d517
+F ext/session/sqlite3changebatch.h e72016998c9a22d439ddfd547b69e1ebac810c24
+F ext/session/sqlite3session.c 421854336ece362552508426d89091c1832148066f0641e8d72e22f58d9241f3
+F ext/session/sqlite3session.h c26e54521584ad26dcb459171d94bbe6412ca26ed4613551c7f0c80aad129abd
+F ext/session/test_session.c 226461035031632255c8098f3bcfa4ea27f0b051efd88857a2a36bcea5c294b9
 F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
 F ext/userauth/user-auth.txt e6641021a9210364665fe625d067617d03f27b04
 F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865f002fc80cb
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 8273bf49ba3b0c8559cb2774495390c31fd61c60
-F main.mk a5412510e5ec952915a7fda34e02079bb4e6ff8f97903f2a3d9ad2dee3e18044
+F main.mk 6c80d0ae4791e299c7cad5f7a6ea01c8861710e8ec1b6d81e92d09ca959b964c
 F mkso.sh fd21c06b063bb16a5d25deea1752c2da6ac3ed83
 F mptest/config01.test 3c6adcbc50b991866855f1977ff172eb6d901271
 F mptest/config02.test 4415dfe36c48785f751e16e32c20b077c28ae504
@@ -508,12 +513,12 @@ F src/analyze.c aabdf3769c7fd9954a8ec508eb7041ae174b66f88d12c47199fabbea9a646467
 F src/attach.c 4431f82f0247bf3aaf91589acafdff77d1882235c95407b36da1585c765fbbc8
 F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
-F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
+F src/bitvec.c 3907fcbe8a0c8c2db58d97087d15cdabbf2842adb9125df9ab9ff87d3db16775
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c b5a74c39d3123dadd190019c0afadd7f62b43dfe0712a39e9d0ff2fe26be5d93
-F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
-F src/btreeInt.h 8ce1332edd89dfd2461d561ac10a0ab5601c8e06200cb5230596c3caaf54482e
-F src/build.c 23f874642825d7eaaeeb7a3281b2b1a75e1d4c4dd9ae4dceddcd908266634214
+F src/btree.c 890831d57243e833584bfcdd0df2720b3e340055901ce65dd0057746c628204a
+F src/btree.h 900067641b64d619e6e2a93bd115c952a52f41d3bee32e551e2a4ceee05fc431
+F src/btreeInt.h 650add92a0ffc8c315406f140325c5f41f0e386848dafbb1e27a72fe7cf6f179
+F src/build.c 53a4c32c6c4c4dd0899641229fd090170f93ab45b622f118a2371df698d68002
 F src/callback.c 4c19af69835787bfe790ac560f3071a824eb629f34e41f97b52ce5235c77de1c
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 026dbdcdbd8c3cde98a88483ee88310ff43150ab164ad768f12cc700a11495ad
@@ -524,7 +529,7 @@ F src/delete.c a8e844af211a48b13b5b358be77a12c860c6a557c21990ad51a548e2536500ce
 F src/expr.c 4907afcb86d72b5525d8767515ce425ec53c7a2d3664441b46cef5b376ee0cba
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c d965ede15d8360c09ed59348940649ee647b192e784466837d7aefa836d1d91e
-F src/func.c 8f72e88cccdee22185133c10f96ccd61dc34c5ea4b1fa9a73c237ef59b2e64f1
+F src/func.c c4b2229aac24b3d7989ef51abae0e5e87e58e8bda3c7b6c55f76d231dbedfb8d
 F src/global.c e83ee571b79ee3adc32e380cf554cf1254bc43763d23786c71721fbcdfbbb965
 F src/hash.c 8d7dda241d0ebdafb6ffdeda3149a412d7df75102cecfc1021c98d6219823b19
 F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
@@ -534,8 +539,8 @@ F src/insert.c 173845e5a6bac96ae937409e4f876b631f26b31dabb9df8fd0eb3b130b2bb3a7
 F src/json.c 7749b98c62f691697c7ee536b570c744c0583cab4a89200fdd0fc2aa8cc8cbd6
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 853385cc7a604157e137585097949252d5d0c731768e16b044608e5c95c3614b
-F src/main.c e946f1d9e30bf49cf399ddf860cfd2319e3a97bbaabfb8e87d6ab985a20d54ad
-F src/malloc.c a9127efdcef92d6934c6339ea9813075b90edc0ce2e5c723556381a3828fb720
+F src/main.c 6f5dff0d731fd653d762cad92021a937f2273bb00cf9628de4727ec019dac662
+F src/malloc.c 4a3785323104678a8b4b0a482fe0c2a80900e7468ddf76ab0f2ea1c79a8ca8cd
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
 F src/mem2.c c8bfc9446fd0798bddd495eb5d9dbafa7d4b7287d8c22d50a83ac9daa26d8a75
@@ -554,33 +559,33 @@ F src/os.c b1c4f2d485961e9a5b6b648c36687d25047c252222e9660b7cc25a6e1ea436ab
 F src/os.h 1ff5ae51d339d0e30d8a9d814f4b8f8e448169304d83a7ed9db66a65732f3e63
 F src/os_common.h b2f4707a603e36811d9b1a13278bffd757857b85
 F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
-F src/os_unix.c 2df2b33db88f00af13805d4573ee126bc5973f9e3b91d03c575fa7ba64e7dc41
-F src/os_win.c a8ea80037e81127ca01959daa87387cc135f325c88dc745376c4f760de852a10
+F src/os_unix.c 1b376305176544b29c38b2f169597ee2ce17739bb29fed6d7579708b99c98876
+F src/os_win.c d55025aeb5b36b5d92d7c09fe709edaf2be901420782540ba4adad86729636a0
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c 74596fc3d5d8a50de32c37225fc300cccd5ea27ea303c5f4b845d6572f999c5f
-F src/pager.h f82e9844166e1585f5786837ddc7709966138ced17f568c16af7ccf946c2baa3
-F src/parse.y 8e67d820030d2655b9942ffe61c1e7e6b96cea2f2f72183533299393907d0564
+F src/pager.c 9ba563d9233b4e33adfcce3e84c709d49c1a2ecbf9697daa9021edbf9577e6c5
+F src/pager.h 7b2ec7bba30b21a97b68d5bdc0dbb82a75f48c4b1457180988f9d409fb789e16
+F src/parse.y 17c50d262d92083badeb60b3ebe4725e19c76548f90aea898ab07d4f2940a7d8
 F src/pcache.c 084e638432c610f95aea72b8509f0845d2791293f39d1b82f0c0a7e089c3bb6b
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 54881292a9a5db202b2c0ac541c5e3ef9a5e8c4f1c1383adb2601d5499a60e65
-F src/pragma.c d1aead03e8418ff586c7cfca344c50a914b8eb06abd841e8e91a982d823671da
-F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
+F src/pragma.c 404c0fe37b51f6def2c9ec6b07c80f0355673f0e74d720dc9a58a78725502417
+F src/pragma.h 1f421360eed1a7721e8c521463df8519a7c8d0d5893ebd9dbfe0dba8de996f8c
 F src/prepare.c c62820c15dcb63013519c8e41d9f928d7478672cc902cfd0581c733c271dbf45
-F src/printf.c 6166a30417b05c5b2f82e1f183f75faa2926ad60531c0b688a57dbc951441a20
-F src/random.c 097dc8b31b8fba5a9aca1697aeb9fd82078ec91be734c16bffda620ced7ab83c
-F src/resolve.c 1655e44c77c51ebbe82924287528a78bd4a4aaaf34189dbae28d19ccf2ca615c
+F src/printf.c e99ee9741e79ae3873458146f59644276657340385ade4e76a5f5d1c25793764
+F src/random.c d4127b3d8ba155e293cc1abb19f70992c147abd5cc911df25582cb481b705974
+F src/resolve.c f0d663c9b1ceeb3e7d262ede872dd3b24b323a7cc11d84c05a39d962e7d64b07
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c 2db8bbf13f57cc9872f9b927546e98f5ea583e9e364182426492a434a994421b
-F src/shell.c.in 08e59f1cb9d9b1180aba52861aaada0c95f6ddd210488719684e160a0724c806
-F src/sqlite.h.in 172528c287399a34f188154017b7268bf82c6d5b780902e361958d2318c4e37c
+F src/select.c 3e8041f760d621232bf8702eb805044c7fbaa7c41659ecbc27fc33e90898aada
+F src/shell.c.in 8490f940c723eb4415426d35da9118118895354e7c6b909dac42474e5d062d50
+F src/sqlite.h.in 31d227e5cc2db23d15381b82932ea3cc5901f81eb632b1bf3b443756406e04fd
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h a988810c9b21c0dc36dc7a62735012339dc76fc7ab448fb0792721d30eacb69d
-F src/sqliteInt.h 8353e96646372efdb0795a13cd9949831b4992c928de8f5c43b2524e8a4c6e7b
+F src/sqliteInt.h 96015cf7d0d6ef411ba1af62a739c5b3b600528acaf93e901afcf91ef13ec7fa
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 4a3da6d77eeb3531cb0dbdf7047772a2a1b99f98c69e90ce009c75fe6328b2c0
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
 F src/tclsqlite.c 4e64ba300a5a26e0f1170e09032429faeb65e45e8f3d1a7833e8edb69fc2979e
-F src/test1.c 1356984e97bff07e4a8cc3863e892f05b3348678a74783bb6f350b76316736f1
+F src/test1.c 95c688261edf59ff77676aca426b343beb9f90d6548ecb16189ce614e5a63620
 F src/test2.c 3efb99ab7f1fc8d154933e02ae1378bac9637da5
 F src/test3.c 61798bb0d38b915067a8c8e03f5a534b431181f802659a6616f9b4ff7d872644
 F src/test4.c 4533b76419e7feb41b40582554663ed3cd77aaa54e135cf76b3205098cd6e664
@@ -595,7 +600,7 @@ F src/test_backup.c bf5da90c9926df0a4b941f2d92825a01bbe090a0
 F src/test_bestindex.c 8294d8223b7f18a3ddb7f9a0e30815dcca4e61681f78b538c870f7d934f88b81
 F src/test_blob.c ae4a0620b478548afb67963095a7417cd06a4ec0a56adb453542203bfdcb31ce
 F src/test_btree.c 8b2dc8b8848cf3a4db93f11578f075e82252a274
-F src/test_config.c 8264637b06a3c1f0727c88d1ea32dcf7986b9e7e358a970cae87cdac8a5b2708
+F src/test_config.c c7a93ef3c0c881e3c46ff14163af886a602317206d82a7dc4ebbf400e661a6ff
 F src/test_delete.c e2fe07646dff6300b48d49b2fee2fe192ed389e834dd635e3b3bac0ce0bf9f8f
 F src/test_demovfs.c 86142ba864d4297d54c5b2e972e74f3141ae4b30f05b3a95824184ed2d3d7f91
 F src/test_devsym.c aff2255ea290d7718da08af30cdf18e470ff7325a5eff63e0057b1496ed66593
@@ -634,19 +639,19 @@ F src/test_windirent.h 90dfbe95442c9762357fe128dc7ae3dc199d006de93eb33ba3972e0a9
 F src/test_window.c cdae419fdcea5bad6dcd9368c685abdad6deb59e9fc8b84b153de513d394ba3f
 F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
 F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
-F src/tokenize.c a38f52058b517929e264094abd0b5fd1e8e145a1aa43bc6f6a72ae5218f96c98
-F src/treeview.c 0bd550f5974565eba541db339906be7a3f9e91beafb879cb40705382887f08e1
+F src/tokenize.c 36eb0799e487759bbe73e5742b82ee676f06cea2515ff578d03c59a74ccf2d6c
+F src/treeview.c 07787f67cd297a6d09d04b8d70c06769c60c9c1d9080378f93929c16f8fd3298
 F src/trigger.c 61bea163b1fa3039bc572ed8312461b978e5c527e5301f302b078f4c1ccdec6a
-F src/update.c c52a7991bece0453d22c77c08469512ee2f1391c12503fd347d1c939220c5877
+F src/update.c c17295f85ad5e81bc040701d76c599915ab847098f2ed29149807c537fdd3cb0
 F src/upsert.c 8789047a8f0a601ea42fa0256d1ba3190c13746b6ba940fe2d25643a7e991937
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
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-F src/vacuum.c bb346170b0b54c6683bba4a5983aea40485597fdf605c87ec8bc2e199fe88cd8
-F src/vdbe.c 3df15f0f2cd9d8faeeea18398a62f16c07fda2bfd8d726186f07508ad69b40e2
+F src/util.c 0be191521ff6d2805995f4910f0b6231b42843678b2efdc1abecaf39929a673f
+F src/vacuum.c 5b7888f917936dda09f98b1fda164cff1dad44fb5e143436bdbb9dc3191ce2df
+F src/vdbe.c 2c7aaff87b2507fc7f6616dc49d6bced7c5b2ea5e40ed540ff69165bbbdcd1f5
 F src/vdbe.h 07641758ca8b4f4c6d81ea667ea167c541e6ece21f5574da11e3d21ec37e2662
 F src/vdbeInt.h 2cad0aeeb106371ed0e0946bab89f60627087068847afc2451c05056961c18da
 F src/vdbeapi.c 602610f1252d59cd69742f78a1e2f6fbae40a4b407f5506a6a7b869b0df08ff2
-F src/vdbeaux.c 328b866880e67526300aa2361c5e50beb3d97dd8746db37dd4aa0135aea60e4d
+F src/vdbeaux.c 829eda97bd0691dee30c775c9e29267efd66fef65ddbfe15d12fac064f802e36
 F src/vdbeblob.c 5e61ce31aca17db8fb60395407457a8c1c7fb471dde405e0cd675974611dcfcd
 F src/vdbemem.c 5ebf05c0182addedb1607ade848e1c83cef40981df94d1abfab0c59288c6064f
 F src/vdbesort.c 43756031ca7430f7aec3ef904824a7883c4ede783e51f280d99b9b65c0796e35
@@ -654,12 +659,12 @@ F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1945f1d2e6be5927ec12c06d89b03ef2a4def34bf8
 F src/vdbevtab.c f99b275366c5fc5e2d99f734729880994ab9500bdafde7fae3b02d562b9d323c
 F src/vtab.c 3d72c780d1ea08906a198e4f033921a658a54590e3ed72c544995d84f3f9464a
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
-F src/wal.c b9df133a705093da8977da5eb202eaadb844839f1c7297c08d33471f5491843d
-F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
+F src/wal.c 419c0a98dd65b9419fd07bdd4f9facc61143c33d57b0dbeffd83cf38a2e0e33e
+F src/wal.h 7ffe787437f20a098af347011967a6d3bb8e5c3dc645e6be59eff44d2b2c5297
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c 9a44063e60d8f42dd9dc8147b8e8dcfc315bbd13e25c395211292c36d828c869
+F src/where.c e7b7c9d37f4f8d14d4d05b20e57ae43712a51ffed7d45f547a23f9c42ee483dd
 F src/whereInt.h b48ca529ffe293c18cbfa8326af18a09e39910de66fb3e96ef788c7cbf8ef3a7
-F src/wherecode.c 0b09abfcb88c61c6a6984a3e065786631ff35495e9bdf865e6b74ab0a1299c5b
+F src/wherecode.c f8acceb057286ed95b66689d1981985228fd925001fdc49dbd3b112f4d739174
 F src/whereexpr.c 55a39f42aaf982574fbf52906371a84cceed98a994422198dfd03db4fce4cc46
 F src/window.c fff1b51757438c664e471d5184634e48dcdf8ea34b640f3b1b0810b1e06de18c
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@@ -743,6 +748,7 @@ F test/backup_malloc.test 0c9abdf74c51e7bedb66d504cd684f28d4bd4027
 F test/badutf.test d5360fc31f643d37a973ab0d8b4fb85799c3169f
 F test/badutf2.test f310fd3b24a491b6b77bccdf14923b85d6ebcce751068c180d93a6b8ff854399
 F test/bc_common.tcl b5e42d80305be95697e6370e015af571e5333a1c
+F test/bc_test1.c e0a092579552e066ed4ce7bcdaecfa69c4aacc8d
 F test/bestindex1.test 856a453dff8c68b4568601eed5a8b5e20b4763af9229f3947c215729ed878db0
 F test/bestindex2.test 394ff8fbf34703391247116d6a44e1c50ee7282236ee77909044573cefc37bc0
 F test/bestindex3.test 34bea272b0e0f835651b16a3931dbe7ac927039be6b2e1cb617bbe1d584b492b
@@ -810,6 +816,15 @@ F test/collateB.test 1e68906951b846570f29f20102ed91d29e634854ee47454d725f2151eca
 F test/colmeta.test 2c765ea61ee37bc43bbe6d6047f89004e6508eb1
 F test/colname.test 87ad5458bb8709312dac0d6755fd30e8e4ca83298d0a9ef6e5c24277a3c3390e
 F test/columncount.test 6fe99c2f35738b0129357a1cf3fa483f76140f4cd8a89014c88c33c876d2638f
+F test/concfault.test e5370cd686f601a01909377cac3bbf13dac56d39dd4ad6b04ccbec9eeeaccb18
+F test/concurrent.test a0248ec6e3e79a5948453649cf86b5b359175cba55ea636b15426d6f0fa6c3da
+F test/concurrent2.test de748c7dd749c77e2af2c4b914b9b09a28ac09608042ca498c0251dc6f46aa1a
+F test/concurrent3.test 530671ac706f6a1d0f4992dbdd33a86408330d03cd90fb9e82ecb1b27f5fd081
+F test/concurrent4.test e0b12cd467137e50259df3b4f837507e82aaa07c35941c88664dc8ed1d089c44
+F test/concurrent5.test 0c16cbf7446af162a14e6def30445e94016064eb994e5aa4ebb2bebc59554176
+F test/concurrent6.test a7860e9ca13bb5fb76bcf41c5524fbfa9c37e6e258ecf84ffb5748a272488c67
+F test/concurrent7.test b96fa5c4cfdf8d5c0bc66b6934214500bad0260884a736f054ccc76e81aae85d
+F test/concurrent8.test b93937e74a8efb8b84f2fea7595b53418c5f29777bbe9cbdb5dc219b3dd72a7d
 F test/conflict.test ac0667090f66130ac77d5fb764655558ca6600dd6d88f670ca9123b61c448337
 F test/conflict2.test 5557909ce683b1073982f5d1b61dfb1d41e369533bfdaf003180c5bc87282dd1
 F test/conflict3.test 81865d9599609aca394fb3b9cd5f561d4729ea5b176bece3644f6ecb540f88ac
@@ -836,7 +851,7 @@ F test/corruptJ.test 4d5ccc4bf959464229a836d60142831ef76a5aa4
 F test/corruptK.test 5b4212fe346699831c5ad559a62c54e11c0611bdde1ea8423a091f9c01aa32af
 F test/corruptL.test ecce40d7b9b909a670a42a45d86e30d927735d7e7f09041af438b19529d35532
 F test/corruptM.test 7d574320e08c1b36caa3e47262061f186367d593a7e305d35f15289cc2c3e067
-F test/corruptN.test 60b5a62944b4f0029ba07edaa5fd8e670539d6b0a8d99db26c068d435675cbfe
+F test/corruptN.test f0b26fda7556581af9667904ce2fa1e5749cd018b56c8fb77bda143d3ab6ccbf
 F test/cost.test b11cdbf9f11ffe8ef99c9881bf390e61fe92baf2182bad1dbe6de59a7295c576
 F test/count.test cd4bd531066e8d77ef8fe1e3fc8253d042072e117ccab214b290cf83f1602249
 F test/countofview.test e17d6e6688cf74f22783c9ec6e788c0790ee4fbbaee713affd00b1ac0bb39b86
@@ -1007,7 +1022,7 @@ F test/fts3conf.test c84bbaec81281c1788aa545ac6e78a6bd6cde2bdbbce2da261690e3659f
 F test/fts3corrupt.test 6732477c5ace050c5758a40a8b5706c8c0cccd416b9c558e0e15224805a40e57
 F test/fts3corrupt2.test e318f0676e5e78d5a4b702637e2bb25265954c08a1b1e4aaf93c7880bb0c67d0
 F test/fts3corrupt3.test 0d5b69a0998b4adf868cc301fc78f3d0707745f1d984ce044c205cdb764b491f
-F test/fts3corrupt4.test 799ff994b964fed7201be6b6b62c7ff2ef7bb3da6c02b9eaf0d96a5a4d9b6ca3
+F test/fts3corrupt4.test 589e043d1114ea02c83530e459ef5c2d6adce63094e72826ed3bceb02e795116
 F test/fts3corrupt5.test 0549f85ec4bd22e992f645f13c59b99d652f2f5e643dac75568bfd23a6db7ed5
 F test/fts3corrupt6.test f417c910254f32c0bc9ead7affa991a1d5aec35b3b32a183ffb05eea78289525
 F test/fts3cov.test 7eacdbefd756cfa4dc2241974e3db2834e9b372ca215880e00032222f32194cf
@@ -1024,8 +1039,8 @@ F test/fts3expr3.test c4d4a7d6327418428c96e0a3a1137c251b8dfbf8
 F test/fts3expr4.test f5b2832549f01b1f7f73389fa21d4b875499bc95bf7c8b36271844888c6a0938
 F test/fts3expr5.test a5b9a053becbdb8e973fbf4d6d3abaabeb42d511d1848bd57931f3e0a1cf983e
 F test/fts3f.test 8c438d5e1cab526b0021988fb1dc70cf3597b006a33ffd6c955ee89929077fe3
-F test/fts3fault.test 798e45af84be7978ca33d5bdc94246eb44724db24174b5d8e9b1ac46c57fb08d
-F test/fts3fault2.test 6a17a11d8034b1c4eca9f3091649273d56c49ff049e2173df8060f94341e9da0
+F test/fts3fault.test f4e1342acfe6d216a001490e8cd52afac1f9ffe4a11bbcdcb296129a45c5df45
+F test/fts3fault2.test 7b2741e5095367238380b0fcdb837f36c24484c7a5f353659b387df63cf039ec
 F test/fts3first.test dbdedd20914c8d539aa3206c9b34a23775644641
 F test/fts3fuzz001.test e3c7b0ce9b04cc02281dcc96812a277f02df03cd7dc082055d87e11eb18aaf56
 F test/fts3join.test ee25def5e763ea8879c19e74f862d5191410ccc7259338887a3685e97f512662
@@ -1168,7 +1183,7 @@ F test/join4.test 1a352e4e267114444c29266ce79e941af5885916
 F test/join5.test d22b6cba8fb59ab3f1c82701434c360705eb12d4ce200c449f37b018fc47681a
 F test/join6.test f809c025fa253f9e150c0e9afd4cef8813257bceeb6f46e04041228c9403cc2c
 F test/join7.test 2268dcbb54b724391dda3748ea95c60d960607ffeed67885675998e7117697f6
-F test/join8.test d0e75bf880a1b1ee8fda57d8187170c5b2ff0c0cd0e1d6d474faa99fe1283d8d
+F test/join8.test ef5fb09a7ce6b59addb8bd16e11607db6c44a0afcac5774a5dc03193fd0a1df5
 F test/join9.test 9056ddd3b0c0f4f9d658f4521038d9a37dc23ead8ca9a505d0b0db2b6a471e05
 F test/joinA.test 7eab225dc1c1ab258a5e62513a4ed7cabbd3db971d59d5d92f4fb6fa14c12f6a
 F test/joinB.test 1b2ba3fc8568b49411787fccbf540570c148e9b6a53a30f80691cb6268098ded
@@ -1183,7 +1198,7 @@ F test/journal3.test 7c3cf23ffc77db06601c1fcfc9743de8441cb77db9d1aa931863d94f5ff
 F test/jrnlmode.test 9b5bc01dac22223cb60ec2d5f97acf568d73820794386de5634dcadbea9e1946
 F test/jrnlmode2.test 8759a1d4657c064637f8b079592651530db738419e1d649c6df7048cd724363d
 F test/jrnlmode3.test 556b447a05be0e0963f4311e95ab1632b11c9eaa
-F test/json101.test 9d46b8e254c4e23306da175dd226d5c4f164db6b294bcea98e5dcd891ba48c91
+F test/json101.test 9f6337e7423d2c1774d1d485c919fc4e11c8f7e423a2f8831f73471983432108
 F test/json102.test 327e77275f338c028faefa2da5164daf6b142a165e3015ff2a6e4251ddc6a0ac
 F test/json103.test 53df87f83a4e5fa0c0a56eb29ff6c94055c6eb919f33316d62161a8880112dbe
 F test/json104.test a502dc01853aada95d721b3b275afbe2dc18fffdac1fea6e96fb20c13586bbb5
@@ -1233,7 +1248,7 @@ F test/mallocJ.test b5d1839da331d96223e5f458856f8ffe1366f62e
 F test/mallocK.test 25897506da0098cea09b302ff432b0fb6d8002773c1e0fc9732aa8b444bfd455
 F test/mallocL.test fb311ff80afddf3b1a75e52289081f4754d901dc
 F test/mallocM.test 78bbe9d3da84a5c679123cdb40d7b2010b18fc46e13897e4f253c6ba6fbff134
-F test/malloc_common.tcl aac62499b76be719fac31e7a3e54a7fd53272e7f
+F test/malloc_common.tcl 806c50379cf4fa65008cd4d5af18273e5dac8ab62d1d4316c76aa2ecd2e54018
 F test/malloctraceviewer.tcl b7a54595270c1d201abf1c3f3d461f27eaf24cdef623ad08a0fe5e411264c8a9
 F test/manydb.test 28385ae2087967aa05c38624cec7d96ec74feb3e
 F test/mem5.test c6460fba403c5703141348cd90de1c294188c68f
@@ -1244,7 +1259,7 @@ F test/memjournal2.test 89a4e0d1084170a281efa4d54c2677599f986f44227f98f7dfae2828
 F test/memleak.test 10b9c6c57e19fc68c32941495e9ba1c50123f6e2
 F test/memsubsys1.test 9e7555a22173b8f1c96c281ce289b338fcba2abe8b157f8798ca195bbf1d347e
 F test/memsubsys2.test 3e4a8d0c05fd3e5fa92017c64666730a520c7e08
-F test/merge1.test 0ade470d77b689c4a64dc7f736527fcd893140bcafa70af8f7b98523cfb83f16
+F test/merge1.test 2de6d6ef8d25402764b1aab49d8f9d7f89208c89a6674e437f76de4c812157b8
 F test/minmax.test fe638b55d77d2375531a8f549b338eafcd9adfbd2f72df37ed77d9b26ca0a71a
 F test/minmax2.test cf9311babb6f0518d04e42fd6a42c619531c4309a9dd790a2c4e9b3bc595e0de
 F test/minmax3.test cc1e8b010136db0d01a6f2a29ba5a9f321034354
@@ -1274,6 +1289,7 @@ F test/mutex2.test bfeaeac2e73095b2ac32285d2756e3a65e681660
 F test/nan.test 437d40e6d0778b050d7750726c0cbd2c9936b81962926e8f8c48ca698f00f4d1
 F test/nockpt.test 8c43b25af63b0bd620cf1b003529e37b6f1dc53bd22690e96a1bd73f78dde53a
 F test/nolock.test f196cf8b8fbea4e2ca345140a2b3f3b0da45c76e
+F test/noop_update.test 74d71bbe5d37f7861cc2402ed620eb165b8e6b00159cdcada7df716420336651
 F test/normalize.test f23b6c5926c59548635fcf39678ac613e726121e073dd902a3062fbb83903b72
 F test/notify1.test 669b2b743618efdc18ca4b02f45423d5d2304abf
 F test/notify2.test 2ecabaa1305083856b7c39cf32816b612740c161
@@ -1285,7 +1301,7 @@ F test/null.test b7ff206a1c60fe01aa2abd33ef9ea83c93727d993ca8a613de86e925c9f2bc6
 F test/nulls1.test 7a5e4346ee4285034100b4cd20e6784f16a9d6c927e44ecdf10034086bbee9c9
 F test/numcast.test 5d126f7f581432e86a90d1e35cac625164aec4a1
 F test/numindex1.test 20a5450d4b056e48cd5db30e659f13347a099823
-F test/offset1.test f06b83657bcf26f9ce805e67450e189e282143b2
+F test/offset1.test 72cca52482cbd5bc687cfa67aa2566c859081b5a353fd2f9da9bbd3914dea1ef
 F test/openv2.test 0d3040974bf402e19b7df4b783e447289d7ab394
 F test/optfuzz-db01.c 9f2fa80b8f84ebbf1f2e8b13421a4e0477fe300f6686fbd76cac1d2db66e0fdc
 F test/optfuzz-db01.txt 21f6bdeadc701cf11528276e2a55c70bfcb846ba42df327f979bd9e7b6ce7041
@@ -1313,7 +1329,6 @@ F test/pagerfault2.test caf4c7facb914fd3b03a17b31ae2b180c8d6ca1f
 F test/pagerfault3.test 1003fcda009bf48a8e22a516e193b6ef0dd1bbd8
 F test/pageropt.test 84e4cc5cbca285357f7906e99b21be4f2bf5abc0
 F test/pagesize.test 5769fc62d8c890a83a503f67d47508dfdc543305
-F test/parser1.test 6ccdf5e459a5dc4673d3273dc311a7e9742ca952dd0551a6a6320d27035ce4b3
 F test/pcache.test c8acbedd3b6fd0f9a7ca887a83b11d24a007972b
 F test/pcache2.test af7f3deb1a819f77a6d0d81534e97d1cf62cd442
 F test/percentile.test 4243af26b8f3f4555abe166f723715a1f74c77ff
@@ -1342,7 +1357,7 @@ F test/randexpr1.test eda062a97e60f9c38ae8d806b03b0ddf23d796df
 F test/rbu.test 168573d353cd0fd10196b87b0caa322c144ef736
 F test/rdonly.test 64e2696c322e3538df0b1ed624e21f9a23ed9ff8
 F test/recover.test ccb8c2623902a92ebb76770edd075cb4f75a4760bb7afde38026572c6e79070d
-F test/regexp1.test 0c3ff80f66b0eff80e623eb5db7a3dad512095c573d78ac23009785f6d8f51ce
+F test/regexp1.test 4a44e014664a109bbb1c37d29d9b61ca5aa5a7f49cc564c95208a80f818e3377
 F test/regexp2.test 55ed41da802b0e284ac7e2fe944be3948f93ff25abbca0361a609acfed1368b5
 F test/reindex.test cd9d6021729910ece82267b4f5e1b5ac2911a7566c43b43c176a6a4732e2118d
 F test/releasetest_data.tcl 11ba48a21ed1c808147b0e77c6e93d204577f4327ffe6d7c3b34cd3c01eac3a2
@@ -1357,7 +1372,7 @@ F test/round1.test 768018b04522ca420b1aba8a24bd76091d269f3bce3902af3ec6ebcee41ab
 F test/rowallock.test 3f88ec6819489d0b2341c7a7528ae17c053ab7cc
 F test/rowhash.test 0bc1d31415e4575d10cacf31e1a66b5cc0f8be81
 F test/rowid.test e29025be95baf6b32f0d5edef59a7633028325896a98f1caa8019559ca910350
-F test/rowvalue.test ff1ffa31cebe12feb6f989e09263f3b1e8c560db94b40fe006126a8435fd6832
+F test/rowvalue.test baf4fa3ec1a8c1c920c3faa5fd25959cb454bbd99ac8960397c34549d9fc4abe
 F test/rowvalue2.test 060d238b7e5639a7c5630cb5e63e311b44efef2b
 F test/rowvalue3.test 1347e25ca11c547c5a6ff0cc5626f95aa9740e9275bfaec096029f57cb2130ce
 F test/rowvalue4.test 441e7e366ac6d939a3a95a574031c56ec2a854077a91d66eee5ff1d86cb5be58
@@ -1390,7 +1405,7 @@ F test/securedel.test 2f70b2449186a1921bd01ec9da407fbfa98c3a7a5521854c300c194b2f
 F test/securedel2.test 2d54c28e46eb1fd6902089958b20b1b056c6f1c5
 F test/select1.test 692e84cfa29c405854c69e8a4027183d64c22952866a123fabbce741a379e889
 F test/select2.test 352480e0e9c66eda9c3044e412abdf5be0215b56
-F test/select3.test 399a0b23f8618bfe07ea24fb67f2952f620d6eba662bccabf6f4f71c2d89e6c9
+F test/select3.test ce4f78bbc809b0513f960f1ee84cdbc5af50ba112c343d5266558a8b2468f656
 F test/select4.test f0684d3da3bccacbe2a1ebadf6fb49d9df6f53acb4c6ebc228a88d0d6054cc7b
 F test/select5.test 8afc5e5dcdebc2be54472e73ebd9cd1adef1225fd15d37a1c62f969159f390ae
 F test/select6.test 9b2fb4ffedf52e1b5703cfcae1212e7a4a063f014c0458d78d29aca3db766d1f
@@ -1691,6 +1706,7 @@ F test/triggerG.test 2b816093c91ba73c733cfa8aedcc210ad819d72a98b1da30768a3c56505
 F test/triggerupfrom.test d1f9e56090408115c522bee626cc33a2f3370f627a5e341d832589d72e3aa271
 F test/trustschema1.test 4e970aef0bfe0cee139703cc7209d0e0f07725d999b180ba50770f49edef1494
 F test/tt3_checkpoint.c ac7ca661d739280c89d9c253897df64a59a49369bd1247207ac0f655b622579d
+F test/tt3_core.c 8cd89ead95410f70e7fb02c79f1e040f9c5ad5cf
 F test/tt3_index.c 39eec10a35f57672225be4d182862152896dee4a
 F test/tt3_lookaside1.c 0377e202c3c2a50d688cb65ba203afeda6fafeb9
 F test/tt3_shared.c b37d22defc944a2ac4c91c927fd06c1d48cd51e2ce9d004fe868625bd2399f93
@@ -1764,7 +1780,7 @@ F test/vtabdistinct.test 7688f0889358f849fd60bbfde1ded38b014b18066076d4bfbb75395
 F test/vtabdrop.test 65d4cf6722972e5499bdaf0c0d70ee3b8133944a4e4bc31862563f32a7edca12
 F test/vtabrhs1.test 9b5ecbc74a689500c33a4b2b36761f9bcc22fcc4e3f9d21066ee0c9c74cf5f6c
 F test/wal.test b7cc6984709f54afbf8441747ced1f646af120bf0c1b1d847bfa39306fbea089
-F test/wal2.test 31f6e2c404b9f2cdf9ca19b105a1742fdc19653c2c936da39e3658c617524046
+F test/wal2.test 88d34cc62bf5460ad6b1f837cd56ab55731bb0637ff99e113b790873d9b60b14
 F test/wal3.test 2a93004bc0fb2b5c29888964024695bade278ab2
 F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
 F test/wal5.test 9c11da7aeccd83a46d79a556ad11a18d3cb15aa9
@@ -1773,7 +1789,7 @@ F test/wal64k.test 2a525c0f45d709bae3765c71045ccec5df7d100ccbd3a7860fdba46c9addb
 F test/wal7.test 2ae8f427d240099cc4b2dfef63cff44e2a68a1bd
 F test/wal8.test d9df3fba4caad5854ed69ed673c68482514203c8
 F test/wal9.test 378e76a9ad09cd9bee06c172ad3547b0129a6750
-F test/wal_common.tcl a98f17fba96206122eff624db0ab13ec377be4fe
+F test/wal_common.tcl 37902864b63794e9bf59393b8887e21a9cbd4db8
 F test/walbak.test 018d4e5a3d45c6298d11b99f09a8ef6876527946
 F test/walbig.test f437473a16cfb314867c6b5d1dbcd519e73e3434
 F test/walblock.test be48f3a75eff0b4456209f26b3ce186c2015497d
@@ -1911,7 +1927,7 @@ F tool/mkmsvcmin.tcl 6ecab9fe22c2c8de4d82d4c46797bda3d2deac8e763885f5a38d0c44a89
 F tool/mkopcodec.tcl 33d20791e191df43209b77d37f0ff0904620b28465cca6990cf8d60da61a07ef
 F tool/mkopcodeh.tcl 5dab48c49a25452257494e9601702ab63adaba6bd54a9b382615fa52661c8f8c
 F tool/mkopts.tcl 680f785fdb09729fd9ac50632413da4eadbdf9071535e3f26d03795828ab07fa
-F tool/mkpragmatab.tcl bd07bd59d45d0f3448e123d6937e9811195f9908a51e09d774609883055bfd3d
+F tool/mkpragmatab.tcl 8dcba40365eceba24f059d82bbc8b61bb647d5a0b8076f24a1876872a1b58832
 F tool/mkshellc.tcl df5d249617f9cc94d5c48eb0401673eb3f31f383ecbc54e8a13ca3dd97e89450
 F tool/mksourceid.c 36aa8020014aed0836fd13c51d6dc9219b0df1761d6b5f58ff5b616211b079b9
 F tool/mkspeedsql.tcl a1a334d288f7adfe6e996f2e712becf076745c97
@@ -1978,11 +1994,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P cd6254fcd32798f7be4e6d827597ddaa2e46ac6e2f0149cd3a3be0416fa18835
-R 4b3e64a86ee9acaa4f97f1ab6ad6f3ae
-T +sym-major-release *
-T +sym-release *
-T +sym-version-3.39.0 *
+P fb45624a319ed56268749d584839fa0a3c35d331513ca41451438dda988f9df8 4635f4a69c8c2a8df242b384a992aea71224e39a2ccab42d8c0b0602f1e826e8
+R 775b113344ca9d46da4fdca9c2001a8a
+T *branch * begin-concurrent-3.39
+T *sym-begin-concurrent-3.39 *
+T -sym-begin-concurrent *
 U drh
-Z f64bfe891f96e530fe80668f0f22f84a
+Z 7c3f404c7741cbf959d90f4576dc159f
 # Remove this line to create a well-formed Fossil manifest.
@@ -1 +1 @@
-14e166f40dbfa6e055543f8301525f2ca2e96a02a57269818b9e69e162e98918
+31304de83ef1dbb186f1776a57eee3f1185f23870352ea4e7e50d204a812fb9c
@@ -171,6 +171,12 @@ int sqlite3BitvecSet(Bitvec *p, u32 i){
  if( p==0 ) return SQLITE_OK;
  assert( i>0 );
  assert( i<=p->iSize );
+  if( i>p->iSize || i==0 ){
+    sqlite3_log(SQLITE_ERROR, 
+        "Bitvec: setting bit %d of bitvec size %d\n", (int)i, (int)p->iSize
+    );
+    abort();
+  }
  i--;
  while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
    u32 bin = i/p->iDivisor;
@@ -480,7 +480,240 @@ static void downgradeAllSharedCacheTableLocks(Btree *p){

 #endif /* SQLITE_OMIT_SHARED_CACHE */

-static void releasePage(MemPage *pPage);         /* Forward reference */
+#ifndef SQLITE_OMIT_CONCURRENT
+/*
+** The following structure - BtreePtrmap - stores the in-memory pointer map
+** used for newly allocated pages in CONCURRENT transactions. Such pages are
+** always allocated in a contiguous block (from the end of the file) starting
+** with page BtreePtrmap.iFirst.
+*/
+typedef struct RollbackEntry RollbackEntry;
+typedef struct PtrmapEntry PtrmapEntry;
+struct PtrmapEntry {
+  Pgno parent;
+  u8 eType;
+};
+struct RollbackEntry {
+  Pgno pgno;
+  Pgno parent;
+  u8 eType;
+};
+struct BtreePtrmap {
+  Pgno iFirst;                    /* First new page number aPtr[0] */
+
+  int nPtrAlloc;                  /* Allocated size of aPtr[] array */
+  PtrmapEntry *aPtr;              /* Array of parent page numbers */
+
+  int nSvpt;                      /* Used size of aSvpt[] array */
+  int nSvptAlloc;                 /* Allocated size of aSvpt[] */
+  int *aSvpt;                     /* First aRollback[] entry for savepoint i */
+
+  int nRollback;                  /* Used size of aRollback[] array */
+  int nRollbackAlloc;             /* Allocated size of aRollback[] array */
+  RollbackEntry *aRollback;       /* Array of rollback entries */
+};
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** If page number pgno is greater than or equal to BtreePtrmap.iFirst, 
+** store an entry for it in the pointer-map structure.
+*/
+static int btreePtrmapStore(
+  BtShared *pBt,
+  Pgno pgno,
+  u8 eType, 
+  Pgno parent
+){
+  BtreePtrmap *pMap = pBt->pMap;
+  if( pgno>=pMap->iFirst ){
+    int iEntry = pgno - pMap->iFirst;
+
+    /* Grow the aPtr[] array as required */
+    while( iEntry>=pMap->nPtrAlloc ){
+      int nNew = pMap->nPtrAlloc ? pMap->nPtrAlloc*2 : 16;
+      PtrmapEntry *aNew = (PtrmapEntry*)sqlite3_realloc(
+          pMap->aPtr, nNew*sizeof(PtrmapEntry)
+      );
+      if( aNew==0 ){
+        return SQLITE_NOMEM;
+      }else{
+        int nByte = (nNew-pMap->nPtrAlloc)*sizeof(PtrmapEntry);
+        memset(&aNew[pMap->nPtrAlloc], 0, nByte);
+        pMap->aPtr = aNew;
+        pMap->nPtrAlloc = nNew;
+      }
+    }
+
+    /* Add an entry to the rollback log if required */
+    if( pMap->nSvpt>0 && pMap->aPtr[iEntry].parent ){
+      if( pMap->nRollback>=pMap->nRollbackAlloc ){
+        int nNew = pMap->nRollback ? pMap->nRollback*2 : 16;
+        RollbackEntry *aNew = (RollbackEntry*)sqlite3_realloc(
+            pMap->aRollback, nNew*sizeof(RollbackEntry)
+        );
+        if( aNew==0 ){
+          return SQLITE_NOMEM;
+        }else{
+          pMap->aRollback = aNew;
+          pMap->nRollbackAlloc = nNew;
+        }
+      }
+
+      pMap->aRollback[pMap->nRollback].pgno = pgno;
+      pMap->aRollback[pMap->nRollback].parent = pMap->aPtr[iEntry].parent;
+      pMap->aRollback[pMap->nRollback].eType = pMap->aPtr[iEntry].eType;
+      pMap->nRollback++;
+    }
+
+    /* Update the aPtr[] array */
+    pMap->aPtr[iEntry].parent = parent;
+    pMap->aPtr[iEntry].eType = eType;
+  }
+
+  return SQLITE_OK;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** Open savepoint iSavepoint, if it is not already open.
+*/
+static int btreePtrmapBegin(BtShared *pBt, int nSvpt){
+  BtreePtrmap *pMap = pBt->pMap;
+  if( pMap && nSvpt>pMap->nSvpt ){
+    int i;
+    if( nSvpt>=pMap->nSvptAlloc ){
+      int nNew = pMap->nSvptAlloc ? pMap->nSvptAlloc*2 : 16;
+      int *aNew = sqlite3_realloc(pMap->aSvpt, sizeof(int) * nNew);
+      if( aNew==0 ){
+        return SQLITE_NOMEM;
+      }else{
+        pMap->aSvpt = aNew;
+        pMap->nSvptAlloc = nNew;
+      }
+    }
+
+    for(i=pMap->nSvpt; i<nSvpt; i++){
+      pMap->aSvpt[i] = pMap->nRollback;
+    }
+    pMap->nSvpt = nSvpt;
+  }
+
+  return SQLITE_OK;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** Rollback (if op==SAVEPOINT_ROLLBACK) or release (if op==SAVEPOINT_RELEASE)
+** savepoint iSvpt.
+*/
+static void btreePtrmapEnd(BtShared *pBt, int op, int iSvpt){
+  BtreePtrmap *pMap = pBt->pMap;
+  if( pMap ){
+    assert( op==SAVEPOINT_ROLLBACK || op==SAVEPOINT_RELEASE );
+    assert( iSvpt>=0 || (iSvpt==-1 && op==SAVEPOINT_ROLLBACK) );
+    if( iSvpt<0 ){
+      pMap->nSvpt = 0;
+      pMap->nRollback = 0;
+      memset(pMap->aPtr, 0, sizeof(Pgno) * pMap->nPtrAlloc);
+    }else if( iSvpt<pMap->nSvpt ){
+      if( op==SAVEPOINT_ROLLBACK ){
+        int ii;
+        for(ii=pMap->nRollback-1; ii>=pMap->aSvpt[iSvpt]; ii--){
+          RollbackEntry *p = &pMap->aRollback[ii];
+          PtrmapEntry *pEntry = &pMap->aPtr[p->pgno - pMap->iFirst];
+          pEntry->parent = p->parent;
+          pEntry->eType = p->eType;
+        }
+      }
+      pMap->nSvpt = iSvpt + (op==SAVEPOINT_ROLLBACK);
+      pMap->nRollback = pMap->aSvpt[iSvpt];
+    }
+  }
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** This function is called after an CONCURRENT transaction is opened on the
+** database. It allocates the BtreePtrmap structure used to track pointers
+** to allocated pages and zeroes the nFree/iTrunk fields in the database 
+** header on page 1.
+*/
+static int btreePtrmapAllocate(BtShared *pBt){
+  int rc = SQLITE_OK;
+  if( pBt->pMap==0 ){
+    BtreePtrmap *pMap = sqlite3_malloc(sizeof(BtreePtrmap));
+    if( pMap==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      memset(&pBt->pPage1->aData[32], 0, sizeof(u32)*2);
+      memset(pMap, 0, sizeof(BtreePtrmap));
+      pMap->iFirst = pBt->nPage + 1;
+      pBt->pMap = pMap;
+    }
+  }
+  return rc;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** Free any BtreePtrmap structure allocated by an earlier call to
+** btreePtrmapAllocate().
+*/
+static void btreePtrmapDelete(BtShared *pBt){
+  BtreePtrmap *pMap = pBt->pMap;
+  if( pMap ){
+    sqlite3_free(pMap->aRollback);
+    sqlite3_free(pMap->aPtr);
+    sqlite3_free(pMap->aSvpt);
+    sqlite3_free(pMap);
+    pBt->pMap = 0;
+  }
+}
+
+/*
+** Check that the pointer-map does not contain any entries with a parent
+** page of 0. Call sqlite3_log() multiple times to output the entire
+** data structure if it does.
+*/
+static void btreePtrmapCheck(BtShared *pBt, Pgno nPage){
+  Pgno i;
+  int bProblem = 0;
+  BtreePtrmap *p = pBt->pMap;
+
+  for(i=p->iFirst; i<=nPage; i++){
+    PtrmapEntry *pEntry = &p->aPtr[i-p->iFirst];
+    if( pEntry->eType==PTRMAP_OVERFLOW1
+     || pEntry->eType==PTRMAP_OVERFLOW2
+     || pEntry->eType==PTRMAP_BTREE
+    ){
+      if( pEntry->parent==0 ){
+        bProblem = 1;
+        break;
+      }
+    }
+  }
+
+  if( bProblem ){
+    for(i=p->iFirst; i<=nPage; i++){
+      PtrmapEntry *pEntry = &p->aPtr[i-p->iFirst];
+      sqlite3_log(SQLITE_CORRUPT, 
+          "btreePtrmapCheck: pgno=%d eType=%d parent=%d", 
+          (int)i, (int)pEntry->eType, (int)pEntry->parent
+      );
+    }
+    abort();
+  }
+}
+
+#else  /* SQLITE_OMIT_CONCURRENT */
+# define btreePtrmapAllocate(x) SQLITE_OK
+# define btreePtrmapDelete(x) 
+# define btreePtrmapBegin(x,y)  SQLITE_OK
+# define btreePtrmapEnd(x,y,z) 
+# define btreePtrmapCheck(y,z) 
+#endif /* SQLITE_OMIT_CONCURRENT */
+
+static void releasePage(MemPage *pPage);  /* Forward reference */
 static void releasePageOne(MemPage *pPage);      /* Forward reference */
 static void releasePageNotNull(MemPage *pPage);  /* Forward reference */

@@ -1005,6 +1238,13 @@ static void ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent, int *pRC){
  /* The super-journal page number must never be used as a pointer map page */
  assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );

+#ifndef SQLITE_OMIT_CONCURRENT
+  if( pBt->pMap ){
+    *pRC = btreePtrmapStore(pBt, key, eType, parent);
+    return;
+  }
+#endif
+
  assert( pBt->autoVacuum );
  if( key==0 ){
    *pRC = SQLITE_CORRUPT_BKPT;
@@ -2315,6 +2555,17 @@ getAndInitPage_error1:
  return rc;
 }

+#ifndef SQLITE_OMIT_CONCURRENT
+/* 
+** Set the value of the MemPage.pgnoRoot variable, if it exists.
+*/
+static void setMempageRoot(MemPage *pPg, u32 pgnoRoot){
+  pPg->pgnoRoot = pgnoRoot;
+}
+#else
+# define setMempageRoot(x,y)
+#endif
+
 /*
 ** Release a MemPage.  This should be called once for each prior
 ** call to btreeGetPage.
@@ -3493,6 +3744,7 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
  BtShared *pBt = p->pBt;
  Pager *pPager = pBt->pPager;
  int rc = SQLITE_OK;
+  int bConcurrent = (p->db->eConcurrent && !ISAUTOVACUUM);

  sqlite3BtreeEnter(p);
  btreeIntegrity(p);
@@ -3580,7 +3832,8 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
      if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){
        rc = SQLITE_READONLY;
      }else{
-        rc = sqlite3PagerBegin(pPager, wrflag>1, sqlite3TempInMemory(p->db));
+        int exFlag = bConcurrent ? -1 : (wrflag>1);
+        rc = sqlite3PagerBegin(pPager, exFlag, sqlite3TempInMemory(p->db));
        if( rc==SQLITE_OK ){
          rc = newDatabase(pBt);
        }else if( rc==SQLITE_BUSY_SNAPSHOT && pBt->inTransaction==TRANS_NONE ){
@@ -3644,6 +3897,15 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
  }

 trans_begun:
+#ifndef SQLITE_OMIT_CONCURRENT
+  if( bConcurrent && rc==SQLITE_OK && sqlite3PagerIsWal(pBt->pPager) ){
+    rc = sqlite3PagerBeginConcurrent(pBt->pPager);
+    if( rc==SQLITE_OK && wrflag ){
+      rc = btreePtrmapAllocate(pBt);
+    }
+  }
+#endif
+
  if( rc==SQLITE_OK ){
    if( pSchemaVersion ){
      *pSchemaVersion = get4byte(&pBt->pPage1->aData[40]);
@@ -3653,7 +3915,11 @@ trans_begun:
      ** open savepoints. If the second parameter is greater than 0 and
      ** the sub-journal is not already open, then it will be opened here.
      */
-      rc = sqlite3PagerOpenSavepoint(pPager, p->db->nSavepoint);
+      int nSavepoint = p->db->nSavepoint;
+      rc = sqlite3PagerOpenSavepoint(pPager, nSavepoint);
+      if( rc==SQLITE_OK && nSavepoint ){
+        rc = btreePtrmapBegin(pBt, nSavepoint);
+      }
    }
  }

@@ -4118,6 +4384,175 @@ static int autoVacuumCommit(Btree *p){
 # define setChildPtrmaps(x) SQLITE_OK
 #endif

+#ifndef SQLITE_OMIT_CONCURRENT
+/*
+** This function is called as part of merging an CONCURRENT transaction with
+** the snapshot at the head of the wal file. It relocates all pages in the
+** range iFirst..iLast, inclusive. It is assumed that the BtreePtrmap 
+** structure at BtShared.pMap contains the location of the pointers to each
+** page in the range.
+**
+** If pnCurrent is NULL, then all pages in the range are moved to currently
+** free locations (i.e. free-list entries) within the database file before page
+** iFirst.
+**
+** Or, if pnCurrent is not NULL, then it points to a value containing the
+** current size of the database file in pages. In this case, all pages are
+** relocated to the end of the database file - page iFirst is relocated to
+** page (*pnCurrent+1), page iFirst+1 to page (*pnCurrent+2), and so on.
+** Value *pnCurrent is set to the new size of the database before this 
+** function returns.
+**
+** If no error occurs, SQLITE_OK is returned. Otherwise, an SQLite error code.
+*/
+static int btreeRelocateRange(
+  BtShared *pBt,                  /* B-tree handle */
+  Pgno iFirst,                    /* First page to relocate */
+  Pgno iLast,                     /* Last page to relocate */
+  Pgno *pnCurrent                 /* If not NULL, IN/OUT: Database size */
+){
+  int rc = SQLITE_OK;
+  BtreePtrmap *pMap = pBt->pMap;
+  Pgno iPg;
+
+  for(iPg=iFirst; iPg<=iLast && rc==SQLITE_OK; iPg++){
+    MemPage *pFree = 0;     /* Page allocated from free-list */
+    MemPage *pPg = 0;
+    Pgno iNew;              /* New page number for pPg */
+    PtrmapEntry *pEntry;    /* Pointer map entry for page iPg */
+
+    if( iPg==PENDING_BYTE_PAGE(pBt) ) continue;
+    pEntry = &pMap->aPtr[iPg - pMap->iFirst];
+
+    if( pEntry->eType==PTRMAP_FREEPAGE ){
+      Pgno dummy;
+      rc = allocateBtreePage(pBt, &pFree, &dummy, iPg, BTALLOC_EXACT);
+      if( pFree ){
+        assert( sqlite3PagerPageRefcount(pFree->pDbPage)==1 );
+        sqlite3PcacheDrop(pFree->pDbPage);
+      }
+      assert( rc!=SQLITE_OK || dummy==iPg );
+    }else if( pnCurrent ){
+      btreeGetPage(pBt, iPg, &pPg, 0);
+      assert( sqlite3PagerIswriteable(pPg->pDbPage) );
+      assert( sqlite3PagerPageRefcount(pPg->pDbPage)==1 );
+      iNew = ++(*pnCurrent);
+      if( iNew==PENDING_BYTE_PAGE(pBt) ) iNew = ++(*pnCurrent);
+      rc = relocatePage(pBt, pPg, pEntry->eType, pEntry->parent, iNew, 1);
+      releasePageNotNull(pPg);
+    }else{
+      rc = allocateBtreePage(pBt, &pFree, &iNew, iFirst-1, BTALLOC_LE);
+      assert( rc!=SQLITE_OK || iNew<iFirst );
+      if( rc==SQLITE_OK ){
+        releasePage(pFree);
+        btreeGetPage(pBt, iPg, &pPg, 0);
+        rc = relocatePage(pBt, pPg, pEntry->eType, pEntry->parent,iNew,1);
+        releasePage(pPg);
+      }
+    }
+  }
+  return rc;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** The b-tree handle passed as the only argument is about to commit an
+** CONCURRENT transaction. At this point it is guaranteed that this is 
+** possible - the wal WRITER lock is held and it is known that there are 
+** no conflicts with committed transactions.
+*/
+static int btreeFixUnlocked(Btree *p){
+  BtShared *pBt = p->pBt;
+  MemPage *pPage1 = pBt->pPage1;
+  u8 *p1 = pPage1->aData;
+  Pager *pPager = pBt->pPager;
+  int rc = SQLITE_OK;
+
+  /* If page 1 of the database is not writable, then no pages were allocated
+  ** or freed by this transaction. In this case no special handling is 
+  ** required. Otherwise, if page 1 is dirty, proceed.  */
+  BtreePtrmap *pMap = pBt->pMap;
+  Pgno iTrunk = get4byte(&p1[32]);
+  Pgno nPage = btreePagecount(pBt);
+  u32 nFree = get4byte(&p1[36]);
+
+  assert( pBt->pMap );
+  rc = sqlite3PagerUpgradeSnapshot(pPager, pPage1->pDbPage);
+  assert( p1==pPage1->aData );
+
+  if( rc==SQLITE_OK ){
+    Pgno nHPage = get4byte(&p1[28]);
+    Pgno nFin = nHPage;         /* Size of db after transaction merge */
+
+    if( sqlite3PagerIswriteable(pPage1->pDbPage) ){
+      Pgno iHTrunk = get4byte(&p1[32]);
+      u32 nHFree = get4byte(&p1[36]);
+
+      btreePtrmapCheck(pBt, nPage);
+
+      /* Attach the head database free list to the end of the current
+      ** transactions free-list (if any).  */
+      if( iTrunk!=0 ){
+        put4byte(&p1[36], nHFree + nFree);
+        put4byte(&p1[32], iTrunk);
+        while( iTrunk ){
+          DbPage *pTrunk = sqlite3PagerLookup(pPager, iTrunk);
+          iTrunk = get4byte((u8*)pTrunk->pData);
+          if( iTrunk==0 ){
+            put4byte((u8*)pTrunk->pData, iHTrunk);
+          }
+          sqlite3PagerUnref(pTrunk);
+        };
+      }
+
+      if( nHPage<(pMap->iFirst-1) ){
+        /* The database consisted of (pMap->iFirst-1) pages when the current
+        ** concurrent transaction was opened. And an concurrent transaction may
+        ** not be executed on an auto-vacuum database - so the db should 
+        ** not have shrunk since the transaction was opened. Therefore nHPage
+        ** should be set to (pMap->iFirst-1) or greater. */
+        rc = SQLITE_CORRUPT_BKPT;
+      }else{
+        /* The current transaction allocated pages pMap->iFirst through
+        ** nPage (inclusive) at the end of the database file. Meanwhile,
+        ** other transactions have allocated (iFirst..nHPage). So move
+        ** pages (iFirst..MIN(nPage,nHPage)) to (MAX(nPage,nHPage)+1). */
+        Pgno iLast = MIN(nPage, nHPage);    /* Last page to move */
+        Pgno nCurrent;                      /* Current size of db */
+
+        nCurrent = MAX(nPage, nHPage);
+        pBt->nPage = nCurrent;
+        rc = btreeRelocateRange(pBt, pMap->iFirst, iLast, &nCurrent);
+
+        /* There are now no collisions with the snapshot at the head of the
+        ** database file. So at this point it would be possible to write
+        ** the transaction out to disk. Before doing so though, attempt to
+        ** relocate some of the new pages to free locations within the body
+        ** of the database file (i.e. free-list entries). */
+        if( rc==SQLITE_OK ){
+          assert( nCurrent!=PENDING_BYTE_PAGE(pBt) );
+          sqlite3PagerSetDbsize(pBt->pPager, nCurrent);
+          nFree = get4byte(&p1[36]);
+          nFin = nCurrent-nFree;
+          if( nCurrent>PENDING_BYTE_PAGE(pBt) && nFin<=PENDING_BYTE_PAGE(pBt) ){
+            nFin--;
+          }
+          nFin = MAX(nFin, nHPage);
+          rc = btreeRelocateRange(pBt, nFin+1, nCurrent, 0);
+        }
+
+        put4byte(&p1[28], nFin);
+      }
+    }
+    sqlite3PagerSetDbsize(pPager, nFin);
+  }
+
+  return rc;
+}
+#else
+# define btreeFixUnlocked(X)  SQLITE_OK
+#endif /* SQLITE_OMIT_CONCURRENT */
+
 /*
 ** This routine does the first phase of a two-phase commit.  This routine
 ** causes a rollback journal to be created (if it does not already exist)
@@ -4149,8 +4584,10 @@ int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zSuperJrnl){
  if( p->inTrans==TRANS_WRITE ){
    BtShared *pBt = p->pBt;
    sqlite3BtreeEnter(p);
+
 #ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->autoVacuum ){
+      assert( ISCONCURRENT==0 );
      rc = autoVacuumCommit(p);
      if( rc!=SQLITE_OK ){
        sqlite3BtreeLeave(p);
@@ -4161,7 +4598,12 @@ int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zSuperJrnl){
      sqlite3PagerTruncateImage(pBt->pPager, pBt->nPage);
    }
 #endif
-    rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zSuperJrnl, 0);
+    if( rc==SQLITE_OK && ISCONCURRENT && p->db->eConcurrent==CONCURRENT_OPEN ){
+      rc = btreeFixUnlocked(p);
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zSuperJrnl, 0);
+    }
    sqlite3BtreeLeave(p);
  }
  return rc;
@@ -4204,6 +4646,11 @@ static void btreeEndTransaction(Btree *p){
    unlockBtreeIfUnused(pBt);
  }

+  /* If this was an CONCURRENT transaction, delete the pBt->pMap object.
+  ** Also call PagerEndConcurrent() to ensure that the pager has discarded
+  ** the record of all pages read within the transaction.  */
+  btreePtrmapDelete(pBt);
+  sqlite3PagerEndConcurrent(pBt->pPager);
  btreeIntegrity(p);
 }

@@ -4433,6 +4880,9 @@ int sqlite3BtreeBeginStmt(Btree *p, int iStatement){
  ** such savepoints while the statement transaction savepoint is active.
  */
  rc = sqlite3PagerOpenSavepoint(pBt->pPager, iStatement);
+  if( rc==SQLITE_OK ){
+    rc = btreePtrmapBegin(pBt, iStatement);
+  }
  sqlite3BtreeLeave(p);
  return rc;
 }
@@ -4456,6 +4906,7 @@ int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
    assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
    assert( iSavepoint>=0 || (iSavepoint==-1 && op==SAVEPOINT_ROLLBACK) );
    sqlite3BtreeEnter(p);
+    btreePtrmapEnd(pBt, op, iSavepoint);
    if( op==SAVEPOINT_ROLLBACK ){
      rc = saveAllCursors(pBt, 0, 0);
    }
@@ -5254,6 +5705,7 @@ const void *sqlite3BtreePayloadFetch(BtCursor *pCur, u32 *pAmt){
 */
 static int moveToChild(BtCursor *pCur, u32 newPgno){
  BtShared *pBt = pCur->pBt;
+  int rc;

  assert( cursorOwnsBtShared(pCur) );
  assert( pCur->eState==CURSOR_VALID );
@@ -5268,7 +5720,12 @@ static int moveToChild(BtCursor *pCur, u32 newPgno){
  pCur->apPage[pCur->iPage] = pCur->pPage;
  pCur->ix = 0;
  pCur->iPage++;
-  return getAndInitPage(pBt, newPgno, &pCur->pPage, pCur, pCur->curPagerFlags);
+  rc = getAndInitPage(pBt, newPgno, &pCur->pPage,
+                        pCur, pCur->curPagerFlags);
+  if( rc==SQLITE_OK ){
+    setMempageRoot(pCur->pPage, pCur->pgnoRoot);
+  }
+  return rc;
 }

 #ifdef SQLITE_DEBUG
@@ -5380,6 +5837,7 @@ static int moveToRoot(BtCursor *pCur){
      pCur->eState = CURSOR_INVALID;
      return rc;
    }
+    setMempageRoot(pCur->pPage, pCur->pgnoRoot);
    pCur->iPage = 0;
    pCur->curIntKey = pCur->pPage->intKey;
  }
@@ -6262,7 +6720,7 @@ static int allocateBtreePage(
  Pgno mxPage;     /* Total size of the database file */

  assert( sqlite3_mutex_held(pBt->mutex) );
-  assert( eMode==BTALLOC_ANY || (nearby>0 && IfNotOmitAV(pBt->autoVacuum)) );
+  assert( eMode==BTALLOC_ANY || (nearby>0 && REQUIRE_PTRMAP ) );
  pPage1 = pBt->pPage1;
  mxPage = btreePagecount(pBt);
  /* EVIDENCE-OF: R-05119-02637 The 4-byte big-endian integer at offset 36
@@ -6272,6 +6730,15 @@ static int allocateBtreePage(
  if( n>=mxPage ){
    return SQLITE_CORRUPT_BKPT;
  }
+
+  /* Ensure page 1 is writable. This function will either change the number
+  ** of pages in the free-list or the size of the database file. Since both
+  ** of these operations involve modifying page 1 header fields, page 1
+  ** will definitely be written by this transaction. If this is an CONCURRENT
+  ** transaction, ensure the BtreePtrmap structure has been allocated.  */
+  rc = sqlite3PagerWrite(pPage1->pDbPage);
+  if( rc ) return rc;
+
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */
    Pgno iTrunk;
@@ -6282,28 +6749,29 @@ static int allocateBtreePage(
    ** shows that the page 'nearby' is somewhere on the free-list, then
    ** the entire-list will be searched for that page.
    */
-#ifndef SQLITE_OMIT_AUTOVACUUM
    if( eMode==BTALLOC_EXACT ){
-      if( nearby<=mxPage ){
-        u8 eType;
-        assert( nearby>0 );
-        assert( pBt->autoVacuum );
-        rc = ptrmapGet(pBt, nearby, &eType, 0);
-        if( rc ) return rc;
-        if( eType==PTRMAP_FREEPAGE ){
-          searchList = 1;
+      assert( ISAUTOVACUUM!=ISCONCURRENT );
+      if( ISAUTOVACUUM ){
+        if( nearby<=mxPage ){
+          u8 eType;
+          assert( nearby>0 );
+          assert( pBt->autoVacuum );
+          rc = ptrmapGet(pBt, nearby, &eType, 0);
+          if( rc ) return rc;
+          if( eType==PTRMAP_FREEPAGE ){
+            searchList = 1;
+          }
        }
+      }else{
+        searchList = 1;
      }
    }else if( eMode==BTALLOC_LE ){
      searchList = 1;
    }
-#endif

    /* Decrement the free-list count by 1. Set iTrunk to the index of the
    ** first free-list trunk page. iPrevTrunk is initially 1.
    */
-    rc = sqlite3PagerWrite(pPage1->pDbPage);
-    if( rc ) return rc;
    put4byte(&pPage1->aData[36], n-1);

    /* The code within this loop is run only once if the 'searchList' variable
@@ -6611,7 +7079,7 @@ static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
  /* If the database supports auto-vacuum, write an entry in the pointer-map
  ** to indicate that the page is free.
  */
-  if( ISAUTOVACUUM ){
+  if( REQUIRE_PTRMAP ){
    ptrmapPut(pBt, iPage, PTRMAP_FREEPAGE, 0, &rc);
    if( rc ) goto freepage_out;
  }
@@ -6942,7 +7410,7 @@ static int fillInCell(
      }
 #endif
      rc = allocateBtreePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0);
-#ifndef SQLITE_OMIT_AUTOVACUUM
+
      /* If the database supports auto-vacuum, and the second or subsequent
      ** overflow page is being allocated, add an entry to the pointer-map
      ** for that page now. 
@@ -6953,14 +7421,13 @@ static int fillInCell(
      ** may misinterpret the uninitialized values and delete the
      ** wrong pages from the database.
      */
-      if( pBt->autoVacuum && rc==SQLITE_OK ){
+      if( REQUIRE_PTRMAP && rc==SQLITE_OK ){
        u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1);
        ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap, &rc);
        if( rc ){
          releasePage(pOvfl);
        }
      }
-#endif
      if( rc ){
        releasePage(pToRelease);
        return rc;
@@ -7107,6 +7574,7 @@ static void insertCell(
    assert( j==0 || pPage->aiOvfl[j-1]<(u16)i ); /* Overflows in sorted order */
    assert( j==0 || i==pPage->aiOvfl[j-1]+1 );   /* Overflows are sequential */
  }else{
+    BtShared *pBt = pPage->pBt;
    int rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc!=SQLITE_OK ){
      *pRC = rc;
@@ -7121,7 +7589,7 @@ static void insertCell(
    ** if it returns successfully */
    assert( idx >= 0 );
    assert( idx >= pPage->cellOffset+2*pPage->nCell+2 || CORRUPT_DB );
-    assert( idx+sz <= (int)pPage->pBt->usableSize );
+    assert( idx+sz <= (int)pBt->usableSize );
    pPage->nFree -= (u16)(2 + sz);
    if( iChild ){
      /* In a corrupt database where an entry in the cell index section of
@@ -7141,14 +7609,12 @@ static void insertCell(
    /* increment the cell count */
    if( (++data[pPage->hdrOffset+4])==0 ) data[pPage->hdrOffset+3]++;
    assert( get2byte(&data[pPage->hdrOffset+3])==pPage->nCell || CORRUPT_DB );
-#ifndef SQLITE_OMIT_AUTOVACUUM
-    if( pPage->pBt->autoVacuum ){
+    if( REQUIRE_PTRMAP ){
      /* The cell may contain a pointer to an overflow page. If so, write
      ** the entry for the overflow page into the pointer map.
      */
      ptrmapPutOvflPtr(pPage, pPage, pCell, pRC);
    }
-#endif
  }
 }

@@ -7688,7 +8154,7 @@ static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){
    ** be marked as dirty. Returning an error code will cause a
    ** rollback, undoing any changes made to the parent page.
    */
-    if( ISAUTOVACUUM ){
+    if( REQUIRE_PTRMAP ){
      ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno, &rc);
      if( szCell>pNew->minLocal ){
        ptrmapPutOvflPtr(pNew, pNew, pCell, &rc);
@@ -7826,7 +8292,7 @@ static void copyNodeContent(MemPage *pFrom, MemPage *pTo, int *pRC){
    /* If this is an auto-vacuum database, update the pointer-map entries
    ** for any b-tree or overflow pages that pTo now contains the pointers to.
    */
-    if( ISAUTOVACUUM ){
+    if( REQUIRE_PTRMAP ){
      *pRC = setChildPtrmaps(pTo);
    }
  }
@@ -7877,7 +8343,8 @@ static int balance_nonroot(
  int iParentIdx,                 /* Index of "the page" in pParent */
  u8 *aOvflSpace,                 /* page-size bytes of space for parent ovfl */
  int isRoot,                     /* True if pParent is a root-page */
-  int bBulk                       /* True if this call is part of a bulk load */
+  int bBulk,                      /* True if this call is part of a bulk load */
+  Pgno pgnoRoot                   /* Root page of b-tree being balanced */
 ){
  BtShared *pBt;               /* The whole database */
  int nMaxCells = 0;           /* Allocated size of apCell, szCell, aFrom. */
@@ -7967,6 +8434,7 @@ static int balance_nonroot(
      memset(apOld, 0, (i+1)*sizeof(MemPage*));
      goto balance_cleanup;
    }
+    setMempageRoot(apOld[i], pgnoRoot);
    if( apOld[i]->nFree<0 ){
      rc = btreeComputeFreeSpace(apOld[i]);
      if( rc ){
@@ -8314,7 +8782,7 @@ static int balance_nonroot(
      cntOld[i] = b.nCell;

      /* Set the pointer-map entry for the new sibling page. */
-      if( ISAUTOVACUUM ){
+      if( REQUIRE_PTRMAP ){
        ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc);
        if( rc!=SQLITE_OK ){
          goto balance_cleanup;
@@ -8410,7 +8878,7 @@ static int balance_nonroot(
  ** updated. This happens below, after the sibling pages have been 
  ** populated, not here.
  */
-  if( ISAUTOVACUUM ){
+  if( REQUIRE_PTRMAP ){
    MemPage *pOld;
    MemPage *pNew = pOld = apNew[0];
    int cntOldNext = pNew->nCell + pNew->nOverflow;
@@ -8603,7 +9071,7 @@ static int balance_nonroot(
    );
    copyNodeContent(apNew[0], pParent, &rc);
    freePage(apNew[0], &rc);
-  }else if( ISAUTOVACUUM && !leafCorrection ){
+  }else if( REQUIRE_PTRMAP && !leafCorrection ){
    /* Fix the pointer map entries associated with the right-child of each
    ** sibling page. All other pointer map entries have already been taken
    ** care of.  */
@@ -8686,7 +9154,7 @@ static int balance_deeper(MemPage *pRoot, MemPage **ppChild){
  if( rc==SQLITE_OK ){
    rc = allocateBtreePage(pBt,&pChild,&pgnoChild,pRoot->pgno,0);
    copyNodeContent(pRoot, pChild, &rc);
-    if( ISAUTOVACUUM ){
+    if( REQUIRE_PTRMAP ){
      ptrmapPut(pBt, pgnoChild, PTRMAP_BTREE, pRoot->pgno, &rc);
    }
  }
@@ -8844,7 +9312,7 @@ static int balance(BtCursor *pCur){
          */
          u8 *pSpace = sqlite3PageMalloc(pCur->pBt->pageSize);
          rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1,
-                               pCur->hints&BTREE_BULKLOAD);
+                               pCur->hints&BTREE_BULKLOAD, pCur->pgnoRoot);
          if( pFree ){
            /* If pFree is not NULL, it points to the pSpace buffer used 
            ** by a previous call to balance_nonroot(). Its contents are
@@ -9213,7 +9681,7 @@ int sqlite3BtreeInsert(
    testcase( pCur->curFlags & BTCF_ValidOvfl );
    invalidateOverflowCache(pCur);
    if( info.nSize==szNew && info.nLocal==info.nPayload 
-     && (!ISAUTOVACUUM || szNew<pPage->minLocal)
+     && (!REQUIRE_PTRMAP || szNew<pPage->minLocal)
    ){
      /* Overwrite the old cell with the new if they are the same size.
      ** We could also try to do this if the old cell is smaller, then add
@@ -9800,7 +10268,8 @@ static int clearDatabasePage(
  BtShared *pBt,           /* The BTree that contains the table */
  Pgno pgno,               /* Page number to clear */
  int freePageFlag,        /* Deallocate page if true */
-  i64 *pnChange            /* Add number of Cells freed to this counter */
+  i64 *pnChange,           /* Add number of Cells freed to this counter */
+  Pgno pgnoRoot
 ){
  MemPage *pPage;
  int rc;
@@ -9815,6 +10284,7 @@ static int clearDatabasePage(
  }
  rc = getAndInitPage(pBt, pgno, &pPage, 0, 0);
  if( rc ) return rc;
+  setMempageRoot(pPage, pgnoRoot);
  if( (pBt->openFlags & BTREE_SINGLE)==0 
   && sqlite3PagerPageRefcount(pPage->pDbPage) != (1 + (pgno==1))
  ){
@@ -9825,14 +10295,16 @@ static int clearDatabasePage(
  for(i=0; i<pPage->nCell; i++){
    pCell = findCell(pPage, i);
    if( !pPage->leaf ){
-      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
+      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange, pgnoRoot);
      if( rc ) goto cleardatabasepage_out;
    }
    BTREE_CLEAR_CELL(rc, pPage, pCell, info);
    if( rc ) goto cleardatabasepage_out;
  }
  if( !pPage->leaf ){
-    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange);
+    rc = clearDatabasePage(
+        pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange, pgnoRoot
+    );
    if( rc ) goto cleardatabasepage_out;
    if( pPage->intKey ) pnChange = 0;
  }
@@ -9878,7 +10350,7 @@ int sqlite3BtreeClearTable(Btree *p, int iTable, i64 *pnChange){
    if( p->hasIncrblobCur ){
      invalidateIncrblobCursors(p, (Pgno)iTable, 0, 1);
    }
-    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
+    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange, (Pgno)iTable);
  }
  sqlite3BtreeLeave(p);
  return rc;
@@ -10785,10 +11257,12 @@ char *sqlite3BtreeIntegrityCheck(
  }
  pBt->db->flags = savedDbFlags;

-  /* Make sure every page in the file is referenced
-  */
  if( !bPartial ){
-    for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){
+    /* Make sure every page in the file is referenced. Skip this if the
+    ** database is currently being written by a CONCURRENT transaction (it 
+    ** may fail as pages that were part of the free-list when the transaction
+    ** was opened cannot be counted).  */
+    for(i=1; ISCONCURRENT==0 && i<=sCheck.nPage && sCheck.mxErr; i++){
 #ifdef SQLITE_OMIT_AUTOVACUUM
      if( getPageReferenced(&sCheck, i)==0 ){
        checkAppendMsg(&sCheck, "Page %d is never used", i);
@@ -11088,6 +11562,102 @@ int sqlite3BtreeIsReadonly(Btree *p){
 */
 int sqlite3HeaderSizeBtree(void){ return ROUND8(sizeof(MemPage)); }

+/*
+** This function is called to ensure that all locks required to commit the
+** current write-transaction to the database file are held. If the db is
+** in rollback mode, this means the EXCLUSIVE lock on the database file.
+**
+** Or, if this is an CONCURRENT transaction on a wal-mode database, the WRITER
+** lock on the wal file. In this case this function also checks that the
+** CONCURRENT transaction can be safely committed (does not commit with any
+** other transaction committed since it was opened).
+**
+** SQLITE_OK is returned if successful. SQLITE_BUSY if the required locks
+** cannot be obtained due to a conflicting lock. If the locks cannot be
+** obtained for an CONCURRENT transaction due to a conflict with an already
+** committed transaction, SQLITE_BUSY_SNAPSHOT is returned. Otherwise, if
+** some other error (OOM, IO, etc.) occurs, the relevant SQLite error code
+** is returned.
+*/
+int sqlite3BtreeExclusiveLock(Btree *p){
+  int rc;
+  Pgno pgno = 0;
+  BtShared *pBt = p->pBt;
+  assert( p->inTrans==TRANS_WRITE && pBt->pPage1 );
+  sqlite3BtreeEnter(p);
+  rc = sqlite3PagerExclusiveLock(pBt->pPager, 
+    (p->db->eConcurrent==CONCURRENT_SCHEMA) ? 0 : pBt->pPage1->pDbPage,
+    &pgno
+  );
+#ifdef SQLITE_OMIT_CONCURRENT
+  assert( pgno==0 );
+#else
+  if( rc==SQLITE_BUSY_SNAPSHOT && pgno ){
+    PgHdr *pPg = 0;
+    int rc2 = sqlite3PagerGet(pBt->pPager, pgno, &pPg, 0);
+    if( rc2==SQLITE_OK ){
+      int bWrite = -1;
+      const char *zObj = 0;
+      const char *zTab = 0;
+      char zContent[17];
+
+      if( pPg ){
+        Pgno pgnoRoot = 0;
+        HashElem *pE;
+        Schema *pSchema;
+        u8 *aData = (u8*)sqlite3PagerGetData(pPg);
+        int i;
+        for(i=0; i<8; i++){
+          static const char hexdigits[] = {
+            '0', '1', '2', '3', '4', '5', '6', '7',
+            '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' 
+          };
+          zContent[i*2] = hexdigits[(aData[i] >> 4)];
+          zContent[i*2+1] = hexdigits[(aData[i] & 0xF)];
+        }
+        zContent[16] = '\0';
+
+        pgnoRoot = ((MemPage*)sqlite3PagerGetExtra(pPg))->pgnoRoot;
+        bWrite = sqlite3PagerIswriteable(pPg);
+        sqlite3PagerUnref(pPg);
+
+        pSchema = sqlite3SchemaGet(p->db, p);
+        if( pSchema ){
+          for(pE=sqliteHashFirst(&pSchema->tblHash); pE; pE=sqliteHashNext(pE)){
+            Table *pTab = (Table *)sqliteHashData(pE);
+            if( pTab->tnum==(int)pgnoRoot ){
+              zObj = pTab->zName;
+              zTab = 0;
+            }else{
+              Index *pIdx;
+              for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+                if( pIdx->tnum==(int)pgnoRoot ){
+                  zObj = pIdx->zName;
+                  zTab = pTab->zName;
+                }
+              }
+            }
+          }
+        }
+      }
+
+      sqlite3_log(SQLITE_OK,
+          "cannot commit CONCURRENT transaction "
+          "- conflict at page %d "
+          "(%s page; part of db %s %s%s%s; content=%s...)",
+          (int)pgno,
+          (bWrite==0?"read-only":(bWrite>0?"read/write":"unknown")),
+          (zTab ? "index" : "table"),
+          (zTab ? zTab : ""), (zTab ? "." : ""), (zObj ? zObj : "UNKNOWN"),
+          zContent
+      );
+    }
+  }
+#endif
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
 #if !defined(SQLITE_OMIT_SHARED_CACHE)
 /*
 ** Return true if the Btree passed as the only argument is sharable.
@@ -350,6 +350,8 @@ sqlite3_uint64 sqlite3BtreeSeekCount(Btree*);
 # define sqlite3BtreeSeekCount(X) 0
 #endif

+int sqlite3BtreeExclusiveLock(Btree *pBt);
+
 #ifndef NDEBUG
 int sqlite3BtreeCursorIsValid(BtCursor*);
 #endif
@@ -408,5 +410,4 @@ int sqlite3BtreeTransferRow(BtCursor*, BtCursor*, i64);
 # define sqlite3SchemaMutexHeld(X,Y,Z) 1
 #endif

-
 #endif /* SQLITE_BTREE_H */
@@ -232,6 +232,7 @@
 typedef struct MemPage MemPage;
 typedef struct BtLock BtLock;
 typedef struct CellInfo CellInfo;
+typedef struct BtreePtrmap BtreePtrmap;

 /*
 ** This is a magic string that appears at the beginning of every
@@ -275,6 +276,9 @@ struct MemPage {
  u8 intKey;           /* True if table b-trees.  False for index b-trees */
  u8 intKeyLeaf;       /* True if the leaf of an intKey table */
  Pgno pgno;           /* Page number for this page */
+#ifndef SQLITE_OMIT_CONCURRENT
+  Pgno pgnoRoot;       /* Root page of b-tree that this page belongs to */
+#endif
  /* Only the first 8 bytes (above) are zeroed by pager.c when a new page
  ** is allocated. All fields that follow must be initialized before use */
  u8 leaf;             /* True if a leaf page */
@@ -456,6 +460,9 @@ struct BtShared {
  Btree *pWriter;       /* Btree with currently open write transaction */
 #endif
  u8 *pTmpSpace;        /* Temp space sufficient to hold a single cell */
+#ifndef SQLITE_OMIT_CONCURRENT
+  BtreePtrmap *pMap;
+#endif
  int nPreformatSize;   /* Size of last cell written by TransferRow() */
 };

@@ -673,12 +680,19 @@ struct BtCursor {
 ** (sqliteMallocRaw), it is not possible to use conditional compilation.
 ** So, this macro is defined instead.
 */
-#ifndef SQLITE_OMIT_AUTOVACUUM
-#define ISAUTOVACUUM (pBt->autoVacuum)
-#else
+#ifdef SQLITE_OMIT_AUTOVACUUM
 #define ISAUTOVACUUM 0
+#else
+#define ISAUTOVACUUM (pBt->autoVacuum)
 #endif

+#ifdef SQLITE_OMIT_CONCURRENT
+# define ISCONCURRENT 0
+#else
+# define ISCONCURRENT (pBt->pMap!=0)
+#endif
+
+#define REQUIRE_PTRMAP (ISAUTOVACUUM || ISCONCURRENT)

 /*
 ** This structure is passed around through all the sanity checking routines
@@ -89,8 +89,10 @@ void sqlite3TableLock(
  u8 isWriteLock,    /* True for a write lock */
  const char *zName  /* Name of the table to be locked */
 ){
+#ifdef SQLITE_OMIT_CONCURRENT
  if( iDb==1 ) return;
  if( !sqlite3BtreeSharable(pParse->db->aDb[iDb].pBt) ) return;
+#endif
  lockTable(pParse, iDb, iTab, isWriteLock, zName);
 }

@@ -331,8 +333,6 @@ void sqlite3NestedParse(Parse *pParse, const char *zFormat, ...){
  memset(PARSE_TAIL(pParse), 0, PARSE_TAIL_SZ);
  db->mDbFlags |= DBFLAG_PreferBuiltin;
  sqlite3RunParser(pParse, zSql);
-  sqlite3DbFree(db, pParse->zErrMsg);
-  pParse->zErrMsg = 0;
  db->mDbFlags = savedDbFlags;
  sqlite3DbFree(db, zSql);
  memcpy(PARSE_TAIL(pParse), saveBuf, PARSE_TAIL_SZ);
@@ -5116,7 +5116,7 @@ void sqlite3BeginTransaction(Parse *pParse, int type){
  }
  v = sqlite3GetVdbe(pParse);
  if( !v ) return;
-  if( type!=TK_DEFERRED ){
+  if( type==TK_IMMEDIATE || type==TK_EXCLUSIVE ){
    for(i=0; i<db->nDb; i++){
      int eTxnType;
      Btree *pBt = db->aDb[i].pBt;
@@ -5131,7 +5131,7 @@ void sqlite3BeginTransaction(Parse *pParse, int type){
      sqlite3VdbeUsesBtree(v, i);
    }
  }
-  sqlite3VdbeAddOp0(v, OP_AutoCommit);
+  sqlite3VdbeAddOp3(v, OP_AutoCommit, 0, 0, (type==TK_CONCURRENT));
 }

 /*
@@ -523,8 +523,9 @@ static void randomFunc(
  sqlite3_value **NotUsed2
 ){
  sqlite_int64 r;
+  sqlite3 *db = sqlite3_context_db_handle(context);
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
-  sqlite3_randomness(sizeof(r), &r);
+  sqlite3FastRandomness(&db->sPrng, sizeof(r), &r);
  if( r<0 ){
    /* We need to prevent a random number of 0x8000000000000000 
    ** (or -9223372036854775808) since when you do abs() of that
@@ -550,6 +551,7 @@ static void randomBlob(
 ){
  sqlite3_int64 n;
  unsigned char *p;
+  sqlite3 *db = sqlite3_context_db_handle(context);
  assert( argc==1 );
  UNUSED_PARAMETER(argc);
  n = sqlite3_value_int64(argv[0]);
@@ -558,7 +560,7 @@ static void randomBlob(
  }
  p = contextMalloc(context, n);
  if( p ){
-    sqlite3_randomness(n, p);
+    sqlite3FastRandomness(&db->sPrng, n, p);
    sqlite3_result_blob(context, (char*)p, n, sqlite3_free);
  }
 }
@@ -3242,7 +3242,7 @@ static int openDatabase(
  db->aDb = db->aDbStatic;
  db->lookaside.bDisable = 1;
  db->lookaside.sz = 0;
-
+  sqlite3FastPrngInit(&db->sPrng);
  assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
  memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
  db->aLimit[SQLITE_LIMIT_WORKER_THREADS] = SQLITE_DEFAULT_WORKER_THREADS;
@@ -4112,8 +4112,11 @@ int sqlite3_test_control(int op, ...){
        sqlite3ShowTriggerStepList(0);
        sqlite3ShowTrigger(0);
        sqlite3ShowTriggerList(0);
+#ifndef SQLITE_OMIT_WINDOWFUNC
        sqlite3ShowWindow(0);
        sqlite3ShowWinFunc(0);
+#endif
+        sqlite3ShowSelect(0);
      }
 #endif
      break;
@@ -4809,6 +4812,35 @@ void sqlite3_snapshot_free(sqlite3_snapshot *pSnapshot){
 }
 #endif /* SQLITE_ENABLE_SNAPSHOT */

+SQLITE_EXPERIMENTAL int sqlite3_wal_info(
+  sqlite3 *db, const char *zDb, 
+  unsigned int *pnPrior, unsigned int *pnFrame
+){
+  int rc = SQLITE_OK;
+
+#ifndef SQLITE_OMIT_WAL
+  Btree *pBt;
+  int iDb;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+
+  sqlite3_mutex_enter(db->mutex);
+  iDb = sqlite3FindDbName(db, zDb);
+  if( iDb<0 ){
+    return SQLITE_ERROR;
+  }
+  pBt = db->aDb[iDb].pBt;
+  rc = sqlite3PagerWalInfo(sqlite3BtreePager(pBt), pnPrior, pnFrame);
+  sqlite3_mutex_leave(db->mutex);
+#endif   /* SQLITE_OMIT_WAL */
+
+  return rc;
+}
+
 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
 /*
 ** Given the name of a compile-time option, return true if that option
@@ -776,8 +776,13 @@ void *sqlite3OomFault(sqlite3 *db){
    }
    DisableLookaside;
    if( db->pParse ){
+      Parse *pParse;
      sqlite3ErrorMsg(db->pParse, "out of memory");
      db->pParse->rc = SQLITE_NOMEM_BKPT;
+      for(pParse=db->pParse->pOuterParse; pParse; pParse = pParse->pOuterParse){
+        pParse->nErr++;
+        pParse->rc = SQLITE_NOMEM;
+      } 
    }
  }
  return 0;
@@ -1177,6 +1177,10 @@ struct unixInodeInfo {
  sem_t *pSem;                    /* Named POSIX semaphore */
  char aSemName[MAX_PATHNAME+2];  /* Name of that semaphore */
 #endif
+#ifdef SQLITE_SHARED_MAPPING
+  sqlite3_int64 nSharedMapping;   /* Size of mapped region in bytes */
+  void *pSharedMapping;           /* Memory mapped region */
+#endif
 };

 /*
@@ -1329,6 +1333,13 @@ static void releaseInodeInfo(unixFile *pFile){
    pInode->nRef--;
    if( pInode->nRef==0 ){
      assert( pInode->pShmNode==0 );
+#ifdef SQLITE_SHARED_MAPPING
+      if( pInode->pSharedMapping ){
+        osMunmap(pInode->pSharedMapping, pInode->nSharedMapping);
+        pInode->pSharedMapping = 0;
+        pInode->nSharedMapping = 0;
+      }
+#endif
      sqlite3_mutex_enter(pInode->pLockMutex);
      closePendingFds(pFile);
      sqlite3_mutex_leave(pInode->pLockMutex);
@@ -2192,6 +2203,14 @@ static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
 ** Close the file.
 */
 static int nolockClose(sqlite3_file *id) {
+#ifdef SQLITE_SHARED_MAPPING
+  unixFile *pFd = (unixFile*)id;
+  if( pFd->pInode ){
+    unixEnterMutex();
+    releaseInodeInfo(pFd);
+    unixLeaveMutex();
+  }
+#endif
  return closeUnixFile(id);
 }

@@ -4045,6 +4064,9 @@ static int unixFileControl(sqlite3_file *id, int op, void *pArg){
      *(i64*)pArg = pFile->mmapSizeMax;
      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
        pFile->mmapSizeMax = newLimit;
+#ifdef SQLITE_SHARED_MAPPING
+        if( pFile->pInode==0 )
+#endif
        if( pFile->mmapSize>0 ){
          unixUnmapfile(pFile);
          rc = unixMapfile(pFile, -1);
@@ -5119,6 +5141,9 @@ static int unixShmUnmap(
 */
 static void unixUnmapfile(unixFile *pFd){
  assert( pFd->nFetchOut==0 );
+#ifdef SQLITE_SHARED_MAPPING
+  if( pFd->pInode ) return;
+#endif
  if( pFd->pMapRegion ){
    osMunmap(pFd->pMapRegion, pFd->mmapSizeActual);
    pFd->pMapRegion = 0;
@@ -5250,6 +5275,28 @@ static int unixMapfile(unixFile *pFd, i64 nMap){
    nMap = pFd->mmapSizeMax;
  }

+#ifdef SQLITE_SHARED_MAPPING
+  if( pFd->pInode ){
+    unixInodeInfo *pInode = pFd->pInode;
+    if( pFd->pMapRegion ) return SQLITE_OK;
+    unixEnterMutex();
+    if( pInode->pSharedMapping==0 ){
+      u8 *pNew = osMmap(0, nMap, PROT_READ, MAP_SHARED, pFd->h, 0);
+      if( pNew==MAP_FAILED ){
+        unixLogError(SQLITE_OK, "mmap", pFd->zPath);
+        pFd->mmapSizeMax = 0;
+      }else{
+        pInode->pSharedMapping = pNew;
+        pInode->nSharedMapping = nMap;
+      }
+    }
+    pFd->pMapRegion = pInode->pSharedMapping;
+    pFd->mmapSizeActual = pFd->mmapSize = pInode->nSharedMapping;
+    unixLeaveMutex();
+    return SQLITE_OK;
+  }
+#endif
+
  assert( nMap>0 || (pFd->mmapSize==0 && pFd->pMapRegion==0) );
  if( nMap!=pFd->mmapSize ){
    unixRemapfile(pFd, nMap);
@@ -5687,6 +5734,9 @@ static int fillInUnixFile(
  if( pLockingStyle == &posixIoMethods
 #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
    || pLockingStyle == &nfsIoMethods
+#endif
+#ifdef SQLITE_SHARED_MAPPING
+    || pLockingStyle == &nolockIoMethods
 #endif
  ){
    unixEnterMutex();
@@ -5855,6 +5905,7 @@ static const char *unixTempFileDir(void){
 static int unixGetTempname(int nBuf, char *zBuf){
  const char *zDir;
  int iLimit = 0;
+  int rc = SQLITE_OK;

  /* It's odd to simulate an io-error here, but really this is just
  ** using the io-error infrastructure to test that SQLite handles this
@@ -5863,18 +5914,26 @@ static int unixGetTempname(int nBuf, char *zBuf){
  zBuf[0] = 0;
  SimulateIOError( return SQLITE_IOERR );

+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
  zDir = unixTempFileDir();
-  if( zDir==0 ) return SQLITE_IOERR_GETTEMPPATH;
-  do{
-    u64 r;
-    sqlite3_randomness(sizeof(r), &r);
-    assert( nBuf>2 );
-    zBuf[nBuf-2] = 0;
-    sqlite3_snprintf(nBuf, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX"%llx%c",
-                     zDir, r, 0);
-    if( zBuf[nBuf-2]!=0 || (iLimit++)>10 ) return SQLITE_ERROR;
-  }while( osAccess(zBuf,0)==0 );
-  return SQLITE_OK;
+  if( zDir==0 ){
+    rc = SQLITE_IOERR_GETTEMPPATH;
+  }else{
+    do{
+      u64 r;
+      sqlite3_randomness(sizeof(r), &r);
+      assert( nBuf>2 );
+      zBuf[nBuf-2] = 0;
+      sqlite3_snprintf(nBuf, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX"%llx%c",
+                       zDir, r, 0);
+      if( zBuf[nBuf-2]!=0 || (iLimit++)>10 ){
+        rc = SQLITE_ERROR;
+        break;
+      }
+    }while( osAccess(zBuf,0)==0 );
+  }
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
+  return rc;
 }

 #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
@@ -1922,6 +1922,7 @@ int sqlite3_win32_set_directory8(
  int rc = sqlite3_initialize();
  if( rc ) return rc;
 #endif
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
  if( type==SQLITE_WIN32_DATA_DIRECTORY_TYPE ){
    ppDirectory = &sqlite3_data_directory;
  }else if( type==SQLITE_WIN32_TEMP_DIRECTORY_TYPE ){
@@ -1936,14 +1937,19 @@ int sqlite3_win32_set_directory8(
    if( zValue && zValue[0] ){
      zCopy = sqlite3_mprintf("%s", zValue);
      if ( zCopy==0 ){
-        return SQLITE_NOMEM_BKPT;
+        rc = SQLITE_NOMEM_BKPT;
+        goto set_directory8_done;
      }
    }
    sqlite3_free(*ppDirectory);
    *ppDirectory = zCopy;
-    return SQLITE_OK;
+    rc = SQLITE_OK;
+  }else{
+    rc = SQLITE_ERROR;
  }
-  return SQLITE_ERROR;
+set_directory8_done:
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
+  return rc;
 }

 /*
@@ -4717,6 +4723,18 @@ static int winMakeEndInDirSep(int nBuf, char *zBuf){
  return 0;
 }

+/*
+** If sqlite3_temp_directory is not, take the mutex and return true.
+**
+** If sqlite3_temp_directory is NULL, omit the mutex and return false.
+*/
+static int winTempDirDefined(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
+  if( sqlite3_temp_directory!=0 ) return 1;
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
+  return 0;
+}
+
 /*
 ** Create a temporary file name and store the resulting pointer into pzBuf.
 ** The pointer returned in pzBuf must be freed via sqlite3_free().
@@ -4753,20 +4771,23 @@ static int winGetTempname(sqlite3_vfs *pVfs, char **pzBuf){
  */
  nDir = nMax - (nPre + 15);
  assert( nDir>0 );
-  if( sqlite3_temp_directory ){
+  if( winTempDirDefined() ){
    int nDirLen = sqlite3Strlen30(sqlite3_temp_directory);
    if( nDirLen>0 ){
      if( !winIsDirSep(sqlite3_temp_directory[nDirLen-1]) ){
        nDirLen++;
      }
      if( nDirLen>nDir ){
+        sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
        sqlite3_free(zBuf);
        OSTRACE(("TEMP-FILENAME rc=SQLITE_ERROR\n"));
        return winLogError(SQLITE_ERROR, 0, "winGetTempname1", 0);
      }
      sqlite3_snprintf(nMax, zBuf, "%s", sqlite3_temp_directory);
    }
+    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
  }
+
 #if defined(__CYGWIN__)
  else{
    static const char *azDirs[] = {
@@ -5555,7 +5576,7 @@ static BOOL winIsVerbatimPathname(
 ** pathname into zOut[].  zOut[] will be at least pVfs->mxPathname
 ** bytes in size.
 */
-static int winFullPathname(
+static int winFullPathnameNoMutex(
  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
  const char *zRelative,        /* Possibly relative input path */
  int nFull,                    /* Size of output buffer in bytes */
@@ -5734,6 +5755,19 @@ static int winFullPathname(
  }
 #endif
 }
+static int winFullPathname(
+  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
+  const char *zRelative,        /* Possibly relative input path */
+  int nFull,                    /* Size of output buffer in bytes */
+  char *zFull                   /* Output buffer */
+){
+  int rc;
+  sqlite3_mutex *pMutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR);
+  sqlite3_mutex_enter(pMutex);
+  rc = winFullPathnameNoMutex(pVfs, zRelative, nFull, zFull);
+  sqlite3_mutex_leave(pMutex);
+  return rc;
+}

 #ifndef SQLITE_OMIT_LOAD_EXTENSION
 /*
@@ -658,6 +658,9 @@ struct Pager {
  u32 cksumInit;              /* Quasi-random value added to every checksum */
  u32 nSubRec;                /* Number of records written to sub-journal */
  Bitvec *pInJournal;         /* One bit for each page in the database file */
+#ifndef SQLITE_OMIT_CONCURRENT
+  Bitvec *pAllRead;           /* Pages read within current CONCURRENT trans. */
+#endif
  sqlite3_file *fd;           /* File descriptor for database */
  sqlite3_file *jfd;          /* File descriptor for main journal */
  sqlite3_file *sjfd;         /* File descriptor for sub-journal */
@@ -915,7 +918,9 @@ static int assert_pager_state(Pager *p){
      if( !pagerUseWal(pPager) ){
        assert( p->eLock>=RESERVED_LOCK );
      }
-      assert( pPager->dbSize==pPager->dbOrigSize );
+#ifndef SQLITE_OMIT_CONCURRENT
+      assert( pPager->dbSize==pPager->dbOrigSize || pPager->pAllRead );
+#endif
      assert( pPager->dbOrigSize==pPager->dbFileSize );
      assert( pPager->dbOrigSize==pPager->dbHintSize );
      assert( pPager->setSuper==0 );
@@ -1800,6 +1805,53 @@ static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
  return rc;
 }

+#ifndef SQLITE_OMIT_CONCURRENT
+/*
+** If they are not already, begin recording all pages read from the pager layer
+** by the b-tree layer This is used by concurrent transactions. Return
+** SQLITE_OK if successful, or an SQLite error code (SQLITE_NOMEM) if an error
+** occurs.
+*/
+int sqlite3PagerBeginConcurrent(Pager *pPager){
+  int rc = SQLITE_OK;
+  if( pPager->pAllRead==0 ){
+    pPager->pAllRead = sqlite3BitvecCreate(pPager->dbSize);
+    pPager->dbOrigSize = pPager->dbSize;
+    if( pPager->pAllRead==0 ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+  return rc;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** Stop recording all pages read from the pager layer by the b-tree layer
+** and discard any current records.
+*/
+void sqlite3PagerEndConcurrent(Pager *pPager){
+  sqlite3BitvecDestroy(pPager->pAllRead);
+  pPager->pAllRead = 0;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** Return true if the database is in wal mode. False otherwise.
+*/
+int sqlite3PagerIsWal(Pager *pPager){
+  return pPager->pWal!=0;
+}
+#endif /* SQLITE_OMIT_CONCURRENT */
+
+/*
+** Free the Pager.pInJournal and Pager.pAllRead bitvec objects.
+*/
+static void pagerFreeBitvecs(Pager *pPager){
+  sqlite3BitvecDestroy(pPager->pInJournal);
+  pPager->pInJournal = 0;
+  sqlite3PagerEndConcurrent(pPager);
+}
+
 /*
 ** This function is a no-op if the pager is in exclusive mode and not
 ** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
@@ -1824,8 +1876,7 @@ static void pager_unlock(Pager *pPager){
       || pPager->eState==PAGER_ERROR 
  );

-  sqlite3BitvecDestroy(pPager->pInJournal);
-  pPager->pInJournal = 0;
+  pagerFreeBitvecs(pPager);
  releaseAllSavepoints(pPager);

  if( pagerUseWal(pPager) ){
@@ -2092,8 +2143,7 @@ static int pager_end_transaction(Pager *pPager, int hasSuper, int bCommit){
  }
 #endif

-  sqlite3BitvecDestroy(pPager->pInJournal);
-  pPager->pInJournal = 0;
+  pagerFreeBitvecs(pPager);
  pPager->nRec = 0;
  if( rc==SQLITE_OK ){
    if( MEMDB || pagerFlushOnCommit(pPager, bCommit) ){
@@ -3103,8 +3153,24 @@ static int pagerRollbackWal(Pager *pPager){
  **   + Reload page content from the database (if refcount>0).
  */
  pPager->dbSize = pPager->dbOrigSize;
-  rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
+  rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager, 
+#ifdef SQLITE_OMIT_CONCURRENT
+      0
+#else
+      pPager->pAllRead!=0
+#endif
+  );
  pList = sqlite3PcacheDirtyList(pPager->pPCache);
+
+#ifndef SQLITE_OMIT_CONCURRENT
+  /* If this is an CONCURRENT transaction, then page 1 must be reread from 
+  ** the db file, even if it is not dirty. This is because the b-tree layer 
+  ** may have already zeroed the nFree and iTrunk header fields.  */
+  if( rc==SQLITE_OK && (pList==0 || pList->pgno!=1) && pPager->pAllRead ){
+    rc = pagerUndoCallback((void*)pPager, 1);
+  }
+#endif
+
  while( pList && rc==SQLITE_OK ){
    PgHdr *pNext = pList->pDirty;
    rc = pagerUndoCallback((void *)pPager, pList->pgno);
@@ -3154,6 +3220,8 @@ static int pagerWalFrames(
      if( p->pgno<=nTruncate ){
        ppNext = &p->pDirty;
        nList++;
+        PAGERTRACE(("TO-WAL %d page %d hash(%08x)\n",
+                     PAGERID(pPager), p->pgno, pager_pagehash(p)));
      }
    }
    assert( pList );
@@ -4225,7 +4293,7 @@ static int syncJournal(Pager *pPager, int newHdr){
  assert( assert_pager_state(pPager) );
  assert( !pagerUseWal(pPager) );

-  rc = sqlite3PagerExclusiveLock(pPager);
+  rc = sqlite3PagerExclusiveLock(pPager, 0, 0);
  if( rc!=SQLITE_OK ) return rc;

  if( !pPager->noSync ){
@@ -4576,6 +4644,12 @@ static int pagerStress(void *p, PgHdr *pPg){
  pPager->aStat[PAGER_STAT_SPILL]++;
  pPg->pDirty = 0;
  if( pagerUseWal(pPager) ){
+#ifndef SQLITE_OMIT_CONCURRENT
+    /* If the transaction is a "BEGIN CONCURRENT" transaction, the page 
+    ** cannot be flushed to disk. Return early in this case. */
+    if( pPager->pAllRead ) return SQLITE_OK;
+#endif
+
    /* Write a single frame for this page to the log. */
    rc = subjournalPageIfRequired(pPg); 
    if( rc==SQLITE_OK ){
@@ -5495,6 +5569,18 @@ static int getPageNormal(
  assert( assert_pager_state(pPager) );
  assert( pPager->hasHeldSharedLock==1 );

+#ifndef SQLITE_OMIT_CONCURRENT
+  /* If this is an CONCURRENT transaction and the page being read was
+  ** present in the database file when the transaction was opened,
+  ** mark it as read in the pAllRead vector.  */
+  pPg = 0;
+  if( pPager->pAllRead && pgno<=pPager->dbOrigSize ){
+    PAGERTRACE(("USING page %d\n", pgno));
+    rc = sqlite3BitvecSet(pPager->pAllRead, pgno);
+    if( rc!=SQLITE_OK ) goto pager_acquire_err;
+  }
+#endif
+
  if( pgno==0 ) return SQLITE_CORRUPT_BKPT;
  pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
  if( pBase==0 ){
@@ -5821,6 +5907,7 @@ static int pager_open_journal(Pager *pPager){
  if( rc!=SQLITE_OK ){
    sqlite3BitvecDestroy(pPager->pInJournal);
    pPager->pInJournal = 0;
+    pPager->journalOff = 0;
  }else{
    assert( pPager->eState==PAGER_WRITER_LOCKED );
    pPager->eState = PAGER_WRITER_CACHEMOD;
@@ -5833,11 +5920,14 @@ static int pager_open_journal(Pager *pPager){
 ** Begin a write-transaction on the specified pager object. If a 
 ** write-transaction has already been opened, this function is a no-op.
 **
-** If the exFlag argument is false, then acquire at least a RESERVED
-** lock on the database file. If exFlag is true, then acquire at least
+** If the exFlag argument is 0, then acquire at least a RESERVED
+** lock on the database file. If exFlag is >0, then acquire at least
 ** an EXCLUSIVE lock. If such a lock is already held, no locking 
 ** functions need be called.
 **
+** If (exFlag<0) and the database is in WAL mode, do not take any locks.
+** The transaction will run in CONCURRENT mode instead.
+**
 ** If the subjInMemory argument is non-zero, then any sub-journal opened
 ** within this transaction will be opened as an in-memory file. This
 ** has no effect if the sub-journal is already opened (as it may be when
@@ -5855,7 +5945,6 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){

  if( pPager->eState==PAGER_READER ){
    assert( pPager->pInJournal==0 );
-
    if( pagerUseWal(pPager) ){
      /* If the pager is configured to use locking_mode=exclusive, and an
      ** exclusive lock on the database is not already held, obtain it now.
@@ -5871,9 +5960,10 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
      /* Grab the write lock on the log file. If successful, upgrade to
      ** PAGER_RESERVED state. Otherwise, return an error code to the caller.
      ** The busy-handler is not invoked if another connection already
-      ** holds the write-lock. If possible, the upper layer will call it.
-      */
-      rc = sqlite3WalBeginWriteTransaction(pPager->pWal);
+      ** holds the write-lock. If possible, the upper layer will call it.  */
+      if( exFlag>=0 ){
+        rc = sqlite3WalBeginWriteTransaction(pPager->pWal);
+      }
    }else{
      /* Obtain a RESERVED lock on the database file. If the exFlag parameter
      ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
@@ -5881,7 +5971,7 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
      ** lock, but not when obtaining the RESERVED lock.
      */
      rc = pagerLockDb(pPager, RESERVED_LOCK);
-      if( rc==SQLITE_OK && exFlag ){
+      if( rc==SQLITE_OK && exFlag>0 ){
        rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
      }
    }
@@ -6181,7 +6271,7 @@ int sqlite3PagerWrite(PgHdr *pPg){
 ** to sqlite3PagerWrite().  In other words, return TRUE if it is ok
 ** to change the content of the page.
 */
-#ifndef NDEBUG
+#if !defined(SQLITE_OMIT_CONCURRENT) || !defined(NDEBUG)
 int sqlite3PagerIswriteable(DbPage *pPg){
  return pPg->flags & PGHDR_WRITEABLE;
 }
@@ -6337,17 +6427,26 @@ int sqlite3PagerSync(Pager *pPager, const char *zSuper){
 }

 /*
-** This function may only be called while a write-transaction is active in
-** rollback. If the connection is in WAL mode, this call is a no-op. 
-** Otherwise, if the connection does not already have an EXCLUSIVE lock on 
-** the database file, an attempt is made to obtain one.
+** This function is called to ensure that all locks required to commit the
+** current write-transaction to the database file are held. If the db is
+** in rollback mode, this means the EXCLUSIVE lock on the database file.
 **
-** If the EXCLUSIVE lock is already held or the attempt to obtain it is
-** successful, or the connection is in WAL mode, SQLITE_OK is returned.
-** Otherwise, either SQLITE_BUSY or an SQLITE_IOERR_XXX error code is 
-** returned.
+** Or, if this is a non-CONCURRENT transaction on a wal-mode database, this
+** function is a no-op.
+**
+** If this is an CONCURRENT transaction on a wal-mode database, this function
+** attempts to obtain the WRITER lock on the wal file and also checks to
+** see that the transaction can be safely committed (does not commit with 
+** any other transaction committed since it was opened).
+**
+** If the required locks are already held or successfully obtained and
+** the transaction can be committed, SQLITE_OK is returned. If a required lock
+** cannot be obtained, SQLITE_BUSY is returned. Or, if the current transaction
+** is CONCURRENT and cannot be committed due to a conflict, SQLITE_BUSY_SNAPSHOT
+** is returned. Otherwise, if some other error occurs (IO error, OOM etc.),
+** and SQLite error code is returned.
 */
-int sqlite3PagerExclusiveLock(Pager *pPager){
+int sqlite3PagerExclusiveLock(Pager *pPager, PgHdr *pPage1, Pgno *piConflict){
  int rc = pPager->errCode;
  assert( assert_pager_state(pPager) );
  if( rc==SQLITE_OK ){
@@ -6359,10 +6458,73 @@ int sqlite3PagerExclusiveLock(Pager *pPager){
    if( 0==pagerUseWal(pPager) ){
      rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
    }
+#ifndef SQLITE_OMIT_CONCURRENT
+    else{
+      if( pPager->pAllRead ){
+        /* This is an CONCURRENT transaction. Attempt to lock the wal database
+        ** here. If SQLITE_BUSY (but not SQLITE_BUSY_SNAPSHOT) is returned,
+        ** invoke the busy-handler and try again for as long as it returns
+        ** non-zero.  */
+        do {
+          rc = sqlite3WalLockForCommit(
+              pPager->pWal, pPage1, pPager->pAllRead, piConflict
+          );
+        }while( rc==SQLITE_BUSY 
+             && pPager->xBusyHandler(pPager->pBusyHandlerArg) 
+        );
+      }
+    }
+#endif /* SQLITE_OMIT_CONCURRENT */
  }
  return rc;
 }

+#ifndef SQLITE_OMIT_CONCURRENT
+/*
+** This function is called as part of committing an CONCURRENT transaction.
+** At this point the wal WRITER lock is held, and all pages in the cache 
+** except for page 1 are compatible with the snapshot at the head of the
+** wal file. 
+**
+** This function updates the in-memory data structures and reloads the
+** contents of page 1 so that the client is operating on the snapshot 
+** at the head of the wal file.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+int sqlite3PagerUpgradeSnapshot(Pager *pPager, DbPage *pPage1){
+  int rc;
+
+  assert( pPager->pWal && pPager->pAllRead );
+  rc = sqlite3WalUpgradeSnapshot(pPager->pWal);
+  if( rc==SQLITE_OK ){
+    rc = readDbPage(pPage1);
+  }
+
+  return rc;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** Set the in-memory cache of the database file size to nSz pages.
+*/
+void sqlite3PagerSetDbsize(Pager *pPager, Pgno nSz){
+  pPager->dbSize = nSz;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** If this is a WAL mode connection and the WRITER lock is currently held,
+** relinquish it.
+*/
+void sqlite3PagerDropExclusiveLock(Pager *pPager){
+  if( pagerUseWal(pPager) ){
+    sqlite3WalEndWriteTransaction(pPager->pWal);
+  }
+}
+#endif  /* SQLITE_OMIT_CONCURRENT */
+
+
 /*
 ** Sync the database file for the pager pPager. zSuper points to the name
 ** of a super-journal file that should be written into the individual
@@ -7376,7 +7538,7 @@ int sqlite3PagerGetJournalMode(Pager *pPager){
 int sqlite3PagerOkToChangeJournalMode(Pager *pPager){
  assert( assert_pager_state(pPager) );
  if( pPager->eState>=PAGER_WRITER_CACHEMOD ) return 0;
-  if( NEVER(isOpen(pPager->jfd) && pPager->journalOff>0) ) return 0;
+  if( isOpen(pPager->jfd) && pPager->journalOff>0 ) return 0;
  return 1;
 }

@@ -7717,6 +7879,11 @@ void sqlite3PagerSnapshotUnlock(Pager *pPager){
 }

 #endif /* SQLITE_ENABLE_SNAPSHOT */
+
+int sqlite3PagerWalInfo(Pager *pPager, u32 *pnPrior, u32 *pnFrame){
+  return sqlite3WalInfo(pPager->pWal, pnPrior, pnFrame);
+}
+
 #endif /* !SQLITE_OMIT_WAL */

 #ifdef SQLITE_ENABLE_ZIPVFS
@@ -163,7 +163,7 @@ void *sqlite3PagerGetExtra(DbPage *);
 void sqlite3PagerPagecount(Pager*, int*);
 int sqlite3PagerBegin(Pager*, int exFlag, int);
 int sqlite3PagerCommitPhaseOne(Pager*,const char *zSuper, int);
-int sqlite3PagerExclusiveLock(Pager*);
+int sqlite3PagerExclusiveLock(Pager*, DbPage *pPage1, Pgno*);
 int sqlite3PagerSync(Pager *pPager, const char *zSuper);
 int sqlite3PagerCommitPhaseTwo(Pager*);
 int sqlite3PagerRollback(Pager*);
@@ -171,6 +171,7 @@ int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
 int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
 int sqlite3PagerSharedLock(Pager *pPager);

+
 #ifndef SQLITE_OMIT_WAL
  int sqlite3PagerCheckpoint(Pager *pPager, sqlite3*, int, int*, int*);
  int sqlite3PagerWalSupported(Pager *pPager);
@@ -225,10 +226,26 @@ void sqlite3PagerTruncateImage(Pager*,Pgno);

 void sqlite3PagerRekey(DbPage*, Pgno, u16);

+#ifndef SQLITE_OMIT_CONCURRENT
+void sqlite3PagerEndConcurrent(Pager*);
+int sqlite3PagerBeginConcurrent(Pager*);
+void sqlite3PagerDropExclusiveLock(Pager*);
+int sqlite3PagerUpgradeSnapshot(Pager *pPager, DbPage*);
+void sqlite3PagerSetDbsize(Pager *pPager, Pgno);
+int sqlite3PagerIsWal(Pager*);
+#else
+# define sqlite3PagerEndConcurrent(x)
+#endif
+
+#if defined(SQLITE_DEBUG) || !defined(SQLITE_OMIT_CONCURRENT)
+int sqlite3PagerIswriteable(DbPage*);
+#endif
+
+int sqlite3PagerWalInfo(Pager*, u32 *pnPrior, u32 *pnFrame);
+
 /* Functions to support testing and debugging. */
 #if !defined(NDEBUG) || defined(SQLITE_TEST)
  Pgno sqlite3PagerPagenumber(DbPage*);
-  int sqlite3PagerIswriteable(DbPage*);
 #endif
 #ifdef SQLITE_TEST
  int *sqlite3PagerStats(Pager*);
@@ -105,6 +105,13 @@
 */
 struct TrigEvent { int a; IdList * b; };

+/*
+** Generate a syntax error
+*/
+static void parserSyntaxError(Parse *pParse, Token *p){
+  sqlite3ErrorMsg(pParse, "near \"%T\": syntax error", p);
+}
+
 struct FrameBound     { int eType; Expr *pExpr; };

 /*
@@ -164,7 +171,16 @@ trans_opt ::= TRANSACTION nm.
 transtype(A) ::= .             {A = TK_DEFERRED;}
 transtype(A) ::= DEFERRED(X).  {A = @X; /*A-overwrites-X*/}
 transtype(A) ::= IMMEDIATE(X). {A = @X; /*A-overwrites-X*/}
-transtype(A) ::= EXCLUSIVE(X). {A = @X; /*A-overwrites-X*/}
+transtype(A) ::= ID(X). {
+   Token *p = &X;
+   if( p->n==9 && sqlite3_strnicmp(p->z,"exclusive",9)==0 ){
+     A = TK_EXCLUSIVE;
+   }else if( p->n==10 && sqlite3_strnicmp(p->z,"concurrent",10)==0 ){
+     A = TK_CONCURRENT;  /*A-overwrites-X*/
+   }else{
+     parserSyntaxError(pParse, p);
+   }
+}
 cmd ::= COMMIT|END(X) trans_opt.   {sqlite3EndTransaction(pParse,@X);}
 cmd ::= ROLLBACK(X) trans_opt.     {sqlite3EndTransaction(pParse,@X);}

@@ -296,7 +312,6 @@ columnname(A) ::= nm(A) typetoken(Y). {sqlite3AddColumn(pParse,A,Y);}
 //
 %token_class id  ID|INDEXED.

-
 // And "ids" is an identifer-or-string.
 //
 %token_class ids  ID|STRING.
@@ -1119,7 +1134,7 @@ expr(A) ::= VARIABLE(X).     {
    Token t = X; /*A-overwrites-X*/
    assert( t.n>=2 );
    if( pParse->nested==0 ){
-      sqlite3ErrorMsg(pParse, "near \"%T\": syntax error", &t);
+      parserSyntaxError(pParse, &t);
      A = 0;
    }else{
      A = sqlite3PExpr(pParse, TK_REGISTER, 0, 0);
@@ -1901,6 +1916,7 @@ filter_clause(A) ::= FILTER LP WHERE expr(X) RP.  { A = X; }
  UPLUS           /* Unary plus */
  TRUTH           /* IS TRUE or IS FALSE or IS NOT TRUE or IS NOT FALSE */
  REGISTER        /* Reference to a VDBE register */
+  CONCURRENT      /* BEGIN CONCURRENT */
  VECTOR          /* Vector */
  SELECT_COLUMN   /* Choose a single column from a multi-column SELECT */
  IF_NULL_ROW     /* the if-null-row operator */
@@ -965,6 +965,7 @@ void sqlite3Pragma(
  **
  */
  case PragTyp_TEMP_STORE_DIRECTORY: {
+    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
    if( !zRight ){
      returnSingleText(v, sqlite3_temp_directory);
    }else{
@@ -974,6 +975,7 @@ void sqlite3Pragma(
        rc = sqlite3OsAccess(db->pVfs, zRight, SQLITE_ACCESS_READWRITE, &res);
        if( rc!=SQLITE_OK || res==0 ){
          sqlite3ErrorMsg(pParse, "not a writable directory");
+          sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
          goto pragma_out;
        }
      }
@@ -991,6 +993,7 @@ void sqlite3Pragma(
      }
 #endif /* SQLITE_OMIT_WSD */
    }
+    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
    break;
  }

@@ -1009,6 +1012,7 @@ void sqlite3Pragma(
  **
  */
  case PragTyp_DATA_STORE_DIRECTORY: {
+    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
    if( !zRight ){
      returnSingleText(v, sqlite3_data_directory);
    }else{
@@ -1018,6 +1022,7 @@ void sqlite3Pragma(
        rc = sqlite3OsAccess(db->pVfs, zRight, SQLITE_ACCESS_READWRITE, &res);
        if( rc!=SQLITE_OK || res==0 ){
          sqlite3ErrorMsg(pParse, "not a writable directory");
+          sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
          goto pragma_out;
        }
      }
@@ -1029,6 +1034,7 @@ void sqlite3Pragma(
      }
 #endif /* SQLITE_OMIT_WSD */
    }
+    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR));
    break;
  }
 #endif
@@ -441,6 +441,15 @@ static const PragmaName aPragmaName[] = {
  /* iArg:      */ 0 },
 #endif
 #endif
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if defined(SQLITE_ENABLE_NOOP_UPDATE)
+ {/* zName:     */ "noop_update",
+  /* ePragTyp:  */ PragTyp_FLAG,
+  /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,
+  /* ColNames:  */ 0, 0,
+  /* iArg:      */ SQLITE_NoopUpdate },
+#endif
 #endif
 {/* zName:     */ "optimize",
  /* ePragTyp:  */ PragTyp_OPTIMIZE,
@@ -803,8 +803,8 @@ void sqlite3_str_vappendf(
      case etSQLESCAPE:           /* %q: Escape ' characters */
      case etSQLESCAPE2:          /* %Q: Escape ' and enclose in '...' */
      case etSQLESCAPE3: {        /* %w: Escape " characters */
-        int i, j, k, n, isnull;
-        int needQuote;
+        i64 i, j, k, n;
+        int needQuote, isnull;
        char ch;
        char q = ((xtype==etSQLESCAPE3)?'"':'\'');   /* Quote character */
        char *escarg;
@@ -111,6 +111,33 @@ void sqlite3_randomness(int N, void *pBuf){
  sqlite3_mutex_leave(mutex);
 }

+/*
+** Initialize a fast PRNG.  A Fast PRNG is called "fast" because it does
+** not need a mutex to operate, though it does use a mutex to initialize.
+** The quality of the randomness is not as good as the global PRNG.
+*/
+void sqlite3FastPrngInit(FastPrng *pPrng){
+  sqlite3_randomness(sizeof(*pPrng), pPrng);
+  pPrng->x |= 1;
+}
+
+/*
+** Generate N bytes of pseudo-randomness using a FastPrng
+*/
+void sqlite3FastRandomness(FastPrng *pPrng, int N, void *P){
+  unsigned char *pOut = (unsigned char*)P;
+  while( N-->0 ){
+    /* "x" is a variant of LFSR called "Xorshift" by George Marsaglia */
+    pPrng->x ^= pPrng->x <<13;
+    pPrng->x ^= pPrng->x >>7;
+    pPrng->x ^= pPrng->x <<17;
+    /* "y" is a LCG using Don Kunth's constants from MMIX */
+    pPrng->y = (pPrng->y)*6364136223846793005LL + 1442695040888963407LL;
+    /* XOR the two streams together to give the final result */
+    *(pOut++) = (pPrng->x ^ pPrng->y) & 0xff;
+  }
+}
+
 #ifndef SQLITE_UNTESTABLE
 /*
 ** For testing purposes, we sometimes want to preserve the state of
@@ -85,33 +85,23 @@ static void resolveAlias(
    sqlite3ExprDelete(db, pDup);
    pDup = 0;
  }else{
+    Expr temp;
    incrAggFunctionDepth(pDup, nSubquery);
    if( pExpr->op==TK_COLLATE ){
      assert( !ExprHasProperty(pExpr, EP_IntValue) );
      pDup = sqlite3ExprAddCollateString(pParse, pDup, pExpr->u.zToken);
    }
-
-    /* Before calling sqlite3ExprDelete(), set the EP_Static flag. This 
-    ** prevents ExprDelete() from deleting the Expr structure itself,
-    ** allowing it to be repopulated by the memcpy() on the following line.
-    ** The pExpr->u.zToken might point into memory that will be freed by the
-    ** sqlite3DbFree(db, pDup) on the last line of this block, so be sure to
-    ** make a copy of the token before doing the sqlite3DbFree().
-    */
-    ExprSetProperty(pExpr, EP_Static);
-    sqlite3ExprDelete(db, pExpr);
-    memcpy(pExpr, pDup, sizeof(*pExpr));
-    if( !ExprHasProperty(pExpr, EP_IntValue) && pExpr->u.zToken!=0 ){
-      assert( (pExpr->flags & (EP_Reduced|EP_TokenOnly))==0 );
-      pExpr->u.zToken = sqlite3DbStrDup(db, pExpr->u.zToken);
-      pExpr->flags |= EP_MemToken;
-    }
+    memcpy(&temp, pDup, sizeof(Expr));
+    memcpy(pDup, pExpr, sizeof(Expr));
+    memcpy(pExpr, &temp, sizeof(Expr));
    if( ExprHasProperty(pExpr, EP_WinFunc) ){
      if( ALWAYS(pExpr->y.pWin!=0) ){
        pExpr->y.pWin->pOwner = pExpr;
      }
    }
-    sqlite3DbFree(db, pDup);
+    sqlite3ParserAddCleanup(pParse,
+      (void(*)(sqlite3*,void*))sqlite3ExprDelete,
+      pDup);
  }
 }

@@ -314,7 +304,7 @@ static int lookupName(
        pTab = pItem->pTab;
        assert( pTab!=0 && pTab->zName!=0 );
        assert( pTab->nCol>0 || pParse->nErr );
-        assert( pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
+        assert( (int)pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
        if( pItem->fg.isNestedFrom ){
          /* In this case, pItem is a subquery that has been formed from a
          ** parenthesized subset of the FROM clause terms.  Example:
@@ -324,7 +324,7 @@ int sqlite3ColumnIndex(Table *pTab, const char *zCol){
 */
 void sqlite3SrcItemColumnUsed(SrcItem *pItem, int iCol){
  assert( pItem!=0 );
-  assert( pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
+  assert( (int)pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
  if( pItem->fg.isNestedFrom ){
    ExprList *pResults;
    assert( pItem->pSelect!=0 );
@@ -1688,7 +1688,7 @@ static void generateSortTail(
    if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
    addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
    VdbeCoverage(v);
-    codeOffset(v, p->iOffset, addrContinue);
+    assert( p->iLimit==0 && p->iOffset==0 );
    sqlite3VdbeAddOp3(v, OP_SorterData, iTab, regSortOut, iSortTab);
    bSeq = 0;
  }else{
@@ -1696,6 +1696,9 @@ static void generateSortTail(
    codeOffset(v, p->iOffset, addrContinue);
    iSortTab = iTab;
    bSeq = 1;
+    if( p->iOffset>0 ){
+      sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
+    }
  }
  for(i=0, iCol=nKey+bSeq-1; i<nColumn; i++){
 #ifdef SQLITE_ENABLE_SORTER_REFERENCES
@@ -2236,7 +2239,7 @@ int sqlite3ColumnsFromExprList(
        if( zName[j]==':' ) nName = j;
      }
      zName = sqlite3MPrintf(db, "%.*z:%u", nName, zName, ++cnt);
-      if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt);
+      if( cnt>3 ) sqlite3FastRandomness(&db->sPrng, sizeof(cnt), &cnt);
    }
    pCol->zCnName = zName;
    pCol->hName = sqlite3StrIHash(zName);
@@ -3688,10 +3691,11 @@ static int multiSelectOrderBy(
  */
  sqlite3VdbeResolveLabel(v, labelEnd);

-  /* Reassembly the compound query so that it will be freed correctly
+  /* Reassemble the compound query so that it will be freed correctly
  ** by the calling function */
  if( pSplit->pPrior ){
-    sqlite3SelectDelete(db, pSplit->pPrior);
+    sqlite3ParserAddCleanup(pParse, 
+       (void(*)(sqlite3*,void*))sqlite3SelectDelete, pSplit->pPrior);
  }
  pSplit->pPrior = pPrior;
  pPrior->pNext = pSplit;
@@ -4122,6 +4126,9 @@ static void renumberCursors(
 **              (17d2) DISTINCT
 **        (17e) the subquery may not contain window functions, and
 **        (17f) the subquery must not be the RHS of a LEFT JOIN.
+**        (17g) either the subquery is the first element of the outer
+**              query or there are no RIGHT or FULL JOINs in any arm
+**              of the subquery.  (This is a duplicate of condition (27b).)
 **
 **        The parent and sub-query may contain WHERE clauses. Subject to
 **        rules (11), (13) and (14), they may also contain ORDER BY,
@@ -4173,7 +4180,11 @@ static void renumberCursors(
 **        See also (3) for restrictions on LEFT JOIN.
 **
 **  (27)  The subquery may not contain a FULL or RIGHT JOIN unless it
-**        is the first element of the parent query.
+**        is the first element of the parent query.  This must be the
+**        the case if:
+**        (27a) the subquery is not compound query, and
+**        (27b) the subquery is a compound query and the RIGHT JOIN occurs
+**              in any arm of the compound query.  (See also (17g).)
 **
 **  (28)  The subquery is not a MATERIALIZED CTE.
 **
@@ -4303,7 +4314,7 @@ static int flattenSubquery(

  assert( pSubSrc->nSrc>0 );  /* True by restriction (7) */
  if( iFrom>0 && (pSubSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
-    return 0;   /* Restriction (27) */
+    return 0;   /* Restriction (27a) */
  }
  if( pSubitem->fg.isCte && pSubitem->u2.pCteUse->eM10d==M10d_Yes ){
    return 0;       /* (28) */
@@ -4323,7 +4334,7 @@ static int flattenSubquery(
  **          NATURAL join or a join that as an ON or USING clause.
  **
  ** These conditions are sufficient to keep an EP_OuterON from being
-  ** flattened into an EP_InnerON.  Restrictions (3a) and (27) prevent
+  ** flattened into an EP_InnerON.  Restrictions (3a) and (27a) prevent
  ** an EP_InnerON from being flattened into an EP_OuterON.
  */
  if( pSubSrc->nSrc>=2
@@ -4365,6 +4376,12 @@ static int flattenSubquery(
      ){
        return 0;
      }
+      if( iFrom>0 && (pSub1->pSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
+        /* Without this restriction, the JT_LTORJ flag would end up being
+        ** omitted on left-hand tables of the right join that is being
+        ** flattened. */
+        return 0;   /* Restrictions (17g), (27b) */
+      }
      testcase( pSub1->pSrc->nSrc>1 );
    }

@@ -5197,6 +5214,7 @@ static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
   || p->pSrc->nSrc!=1
   || p->pSrc->a[0].pSelect
   || pAggInfo->nFunc!=1
+   || p->pHaving
  ){
    return 0;
  }
@@ -5898,7 +5916,7 @@ static int selectExpander(Walker *pWalker, Select *p){
            zTabName = pTab->zName;
          }
          if( db->mallocFailed ) break;
-          assert( pFrom->fg.isNestedFrom == IsNestedFrom(pFrom->pSelect) );
+          assert( (int)pFrom->fg.isNestedFrom == IsNestedFrom(pFrom->pSelect) );
          if( pFrom->fg.isNestedFrom ){
            assert( pFrom->pSelect!=0 );
            pNestedFrom = pFrom->pSelect->pEList;
@@ -6827,7 +6845,9 @@ int sqlite3Select(
    ){
      SELECTTRACE(0x100,pParse,p,
                ("omit superfluous ORDER BY on %r FROM-clause subquery\n",i+1));
-      sqlite3ExprListDelete(db, pSub->pOrderBy);
+      sqlite3ParserAddCleanup(pParse, 
+         (void(*)(sqlite3*,void*))sqlite3ExprListDelete,
+         pSub->pOrderBy);
      pSub->pOrderBy = 0;
    }

@@ -11990,7 +11990,7 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
  char **argv;
 #endif
 #ifdef SQLITE_DEBUG
-  sqlite3_uint64 mem_main_enter = sqlite3_memory_used();
+  sqlite3_int64 mem_main_enter = sqlite3_memory_used();
 #endif
  char *zErrMsg = 0;
 #ifdef SQLITE_SHELL_WASM_MODE
@@ -12169,15 +12169,6 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
      n = (int)integerValue(cmdline_option_value(argc,argv,++i));
      if( n<0 ) n = 0;
      sqlite3_config(SQLITE_CONFIG_LOOKASIDE, sz, n);
-      if( sz*n==0 ) data.shellFlgs &= ~SHFLG_Lookaside;
-    }else if( strcmp(z,"-threadsafe")==0 ){
-      int n;
-      n = (int)integerValue(cmdline_option_value(argc,argv,++i));
-      switch( n ){
-         case 0:  sqlite3_config(SQLITE_CONFIG_SINGLETHREAD);  break;
-         case 2:  sqlite3_config(SQLITE_CONFIG_MULTITHREAD);   break;
-         default: sqlite3_config(SQLITE_CONFIG_SERIALIZED);    break;
-      }
 #ifdef SQLITE_ENABLE_VFSTRACE
    }else if( strcmp(z,"-vfstrace")==0 ){
      extern int vfstrace_register(
@@ -6282,7 +6282,7 @@ sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
 **
 ** ^The sqlite3_db_name(D,N) interface returns a pointer to the schema name
 ** for the N-th database on database connection D, or a NULL pointer of N is
-** out of range.  An N alue of 0 means the main database file.  An N of 1 is
+** out of range.  An N value of 0 means the main database file.  An N of 1 is
 ** the "temp" schema.  Larger values of N correspond to various ATTACH-ed
 ** databases.
 **
@@ -10276,6 +10276,31 @@ SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp(
 */
 SQLITE_EXPERIMENTAL int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb);

+/*
+** CAPI3REF: Wal related information regarding the most recent COMMIT
+** EXPERIMENTAL
+**
+** This function reports on the state of the wal file (if any) for database 
+** zDb, which should be "main", "temp", or the name of the attached database.
+** Its results - the values written to the output parameters - are only
+** defined if the most recent SQL command on the connection was a successful 
+** COMMIT that wrote data to wal-mode database zDb.
+**
+** Assuming the above conditions are met, output parameter (*pnFrame) is set
+** to the total number of frames in the wal file. Parameter (*pnPrior) is
+** set to the number of frames that were present in the wal file before the
+** most recent transaction was committed. So that the number of frames written
+** by the most recent transaction is (*pnFrame)-(*pnPrior).
+**
+** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code. It
+** is not an error if this function is called at a time when the results
+** are undefined.
+*/
+SQLITE_EXPERIMENTAL int sqlite3_wal_info(
+  sqlite3 *db, const char *zDb, 
+  unsigned int *pnPrior, unsigned int *pnFrame
+);
+
 /*
 ** CAPI3REF: Serialize a database
 **
@@ -198,6 +198,11 @@
 */
 #include "sqlite3.h"

+/*
+** Reuse the STATIC_LRU for mutex access to sqlite3_temp_directory.
+*/
+#define SQLITE_MUTEX_STATIC_TEMPDIR SQLITE_MUTEX_STATIC_VFS1
+
 /*
 ** Include the configuration header output by 'configure' if we're using the
 ** autoconf-based build
@@ -1178,6 +1183,7 @@ typedef struct DbFixer DbFixer;
 typedef struct Schema Schema;
 typedef struct Expr Expr;
 typedef struct ExprList ExprList;
+typedef struct FastPrng FastPrng;
 typedef struct FKey FKey;
 typedef struct FuncDestructor FuncDestructor;
 typedef struct FuncDef FuncDef;
@@ -1301,6 +1307,14 @@ typedef int VList;
 # define SQLITE_DEFAULT_WAL_SYNCHRONOUS SQLITE_DEFAULT_SYNCHRONOUS
 #endif

+/*
+** State of a simple PRNG used for the per-connection and per-pager
+** pseudo-random number generators.
+*/
+struct FastPrng {
+  sqlite3_uint64 x, y;
+};
+
 /*
 ** Each database file to be accessed by the system is an instance
 ** of the following structure.  There are normally two of these structures
@@ -1547,6 +1561,7 @@ struct sqlite3 {
  u32 dbOptFlags;               /* Flags to enable/disable optimizations */
  u8 enc;                       /* Text encoding */
  u8 autoCommit;                /* The auto-commit flag. */
+  u8 eConcurrent;               /* CONCURRENT_* value */
  u8 temp_store;                /* 1: file 2: memory 0: default */
  u8 mallocFailed;              /* True if we have seen a malloc failure */
  u8 bBenignMalloc;             /* Do not require OOMs if true */
@@ -1560,6 +1575,7 @@ struct sqlite3 {
  u8 nSqlExec;                  /* Number of pending OP_SqlExec opcodes */
  u8 eOpenState;                /* Current condition of the connection */
  int nextPagesize;             /* Pagesize after VACUUM if >0 */
+  FastPrng sPrng;               /* State of the per-connection PRNG */
  i64 nChange;                  /* Value returned by sqlite3_changes() */
  i64 nTotalChange;             /* Value returned by sqlite3_total_changes() */
  int aLimit[SQLITE_N_LIMIT];   /* Limits */
@@ -1669,6 +1685,13 @@ struct sqlite3 {
 #endif
 };

+/*
+** Candidate values for sqlite3.eConcurrent
+*/
+#define CONCURRENT_NONE   0
+#define CONCURRENT_OPEN   1
+#define CONCURRENT_SCHEMA 2
+
 /*
 ** A macro to discover the encoding of a database.
 */
@@ -1729,6 +1752,9 @@ struct sqlite3 {
                                          /*   the count using a callback. */
 #define SQLITE_CorruptRdOnly  HI(0x00002) /* Prohibit writes due to error */

+/* Flags used by the Pragma noop_update enhancement */
+#define SQLITE_NoopUpdate     HI(0x0001000) /* UPDATE operations are no-ops */
+
 /* Flags used only if debugging */
 #ifdef SQLITE_DEBUG
 #define SQLITE_SqlTrace       HI(0x0100000) /* Debug print SQL as it executes */
@@ -4474,6 +4500,7 @@ char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
  void sqlite3TreeViewSelect(TreeView*, const Select*, u8);
  void sqlite3TreeViewWith(TreeView*, const With*, u8);
  void sqlite3TreeViewUpsert(TreeView*, const Upsert*, u8);
+#if TREETRACE_ENABLED
  void sqlite3TreeViewDelete(const With*, const SrcList*, const Expr*,
                             const ExprList*,const Expr*, const Trigger*);
  void sqlite3TreeViewInsert(const With*, const SrcList*,
@@ -4482,6 +4509,7 @@ char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
  void sqlite3TreeViewUpdate(const With*, const SrcList*, const ExprList*,
                             const Expr*, int, const ExprList*, const Expr*,
                             const Upsert*, const Trigger*);
+#endif
 #ifndef SQLITE_OMIT_TRIGGER
  void sqlite3TreeViewTriggerStep(TreeView*, const TriggerStep*, u8, u8);
  void sqlite3TreeViewTrigger(TreeView*, const Trigger*, u8, u8);
@@ -4747,6 +4775,8 @@ Vdbe *sqlite3GetVdbe(Parse*);
 void sqlite3PrngSaveState(void);
 void sqlite3PrngRestoreState(void);
 #endif
+void sqlite3FastPrngInit(FastPrng*);
+void sqlite3FastRandomness(FastPrng*, int N, void *P);
 void sqlite3RollbackAll(sqlite3*,int);
 void sqlite3CodeVerifySchema(Parse*, int);
 void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
@@ -8227,6 +8227,41 @@ static int SQLITE_TCLAPI test_dbconfig_maindbname_icecube(
  }
 }

+/*
+** Usage: sqlite3_wal_info DB DBNAME
+*/
+static int SQLITE_TCLAPI test_wal_info(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  int rc;
+  sqlite3 *db;
+  char *zName;
+  unsigned int nPrior;
+  unsigned int nFrame;
+
+  if( objc!=3 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB DBNAME");
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+  zName = Tcl_GetString(objv[2]);
+
+  rc = sqlite3_wal_info(db, zName, &nPrior, &nFrame);
+  if( rc!=SQLITE_OK ){
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+    return TCL_ERROR;
+  }else{
+    Tcl_Obj *pNew = Tcl_NewObj();
+    Tcl_ListObjAppendElement(interp, pNew, Tcl_NewWideIntObj((i64)nPrior));
+    Tcl_ListObjAppendElement(interp, pNew, Tcl_NewWideIntObj((i64)nFrame));
+    Tcl_SetObjResult(interp, pNew);
+  }
+  return TCL_OK;
+}
+
 /*
 ** Usage: sqlite3_mmap_warm DB DBNAME
 */
@@ -8790,8 +8825,9 @@ int Sqlitetest1_Init(Tcl_Interp *interp){
     { "sqlite3_snapshot_open_blob", test_snapshot_open_blob, 0 },
     { "sqlite3_snapshot_cmp_blob", test_snapshot_cmp_blob, 0 },
 #endif
-     { "sqlite3_delete_database", test_delete_database,    0 },
-     { "atomic_batch_write",      test_atomic_batch_write, 0 },
+     { "sqlite3_delete_database", test_delete_database, 0 },
+     { "sqlite3_wal_info", test_wal_info, 0 },
+     { "atomic_batch_write",      test_atomic_batch_write,     0   },
     { "sqlite3_mmap_warm",       test_mmap_warm,          0 },
     { "sqlite3_config_sorterref", test_config_sorterref,   0 },
     { "sqlite3_autovacuum_pages", test_autovacuum_pages,   0 },
@@ -681,6 +681,12 @@ Tcl_SetVar2(interp, "sqlite_options", "mergesort", "1", TCL_GLOBAL_ONLY);
  Tcl_SetVar2(interp, "sqlite_options", "truncate_opt", "1", TCL_GLOBAL_ONLY);
 #endif

+#ifndef SQLITE_OMIT_CONCURRENT
+  Tcl_SetVar2(interp, "sqlite_options", "concurrent", "1", TCL_GLOBAL_ONLY);
+#else
+  Tcl_SetVar2(interp, "sqlite_options", "concurrent", "0", TCL_GLOBAL_ONLY);
+#endif
+
 #ifdef SQLITE_OMIT_UTF16
  Tcl_SetVar2(interp, "sqlite_options", "utf16", "0", TCL_GLOBAL_ONLY);
 #else
@@ -614,6 +614,7 @@ int sqlite3RunParser(Parse *pParse, const char *zSql){
    mxSqlLen -= n;
    if( mxSqlLen<0 ){
      pParse->rc = SQLITE_TOOBIG;
+      pParse->nErr++;
      break;
    }
 #ifndef SQLITE_OMIT_WINDOWFUNC
@@ -100,8 +100,8 @@ void sqlite3TreeViewColumnList(
  sqlite3TreeViewLine(pView, "COLUMNS");
  for(i=0; i<nCol; i++){
    u16 flg = aCol[i].colFlags;
-    int moreToFollow = i<(nCol - 1);
-    sqlite3TreeViewPush(&pView, moreToFollow);
+    int colMoreToFollow = i<(nCol - 1);
+    sqlite3TreeViewPush(&pView, colMoreToFollow);
    sqlite3TreeViewLine(pView, 0);
    printf(" %s", aCol[i].zCnName);
    switch( aCol[i].eCType ){
@@ -232,7 +232,7 @@ void sqlite3TreeViewSrcList(TreeView *pView, const SrcList *pSrc){
        Table *pTab = pItem->pTab;
        sqlite3TreeViewColumnList(pView, pTab->aCol, pTab->nCol, 1);
      }
-      assert( pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
+      assert( (int)pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
      sqlite3TreeViewSelect(pView, pItem->pSelect, (--n)>0);
    }
    if( pItem->fg.isTabFunc ){
@@ -999,6 +999,7 @@ void sqlite3TreeViewUpsert(
  sqlite3TreeViewPop(&pView);
 }

+#if TREETRACE_ENABLED
 /*
 ** Generate a human-readable diagram of the data structure that go
 ** into generating an DELETE statement.
@@ -1052,7 +1053,9 @@ void sqlite3TreeViewDelete(
  }
  sqlite3TreeViewPop(&pView);
 }
+#endif /* TREETRACE_ENABLED */

+#if TREETRACE_ENABLED
 /*
 ** Generate a human-readable diagram of the data structure that go
 ** into generating an INSERT statement.
@@ -1120,7 +1123,9 @@ void sqlite3TreeViewInsert(
  }
  sqlite3TreeViewPop(&pView);
 }
+#endif /* TREETRACE_ENABLED */

+#if TREETRACE_ENABLED
 /*
 ** Generate a human-readable diagram of the data structure that go
 ** into generating an UPDATE statement.
@@ -1196,6 +1201,7 @@ void sqlite3TreeViewUpdate(
  }
  sqlite3TreeViewPop(&pView);
 }
+#endif /* TREETRACE_ENABLED */

 #ifndef SQLITE_OMIT_TRIGGER
 /*
@@ -461,6 +461,17 @@ void sqlite3Update(
  */
  chngRowid = chngPk = 0;
  for(i=0; i<pChanges->nExpr; i++){
+#if defined(SQLITE_ENABLE_NOOP_UPDATE) && !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+    if( db->flags & SQLITE_NoopUpdate ){
+      Token x;
+      sqlite3ExprDelete(db, pChanges->a[i].pExpr);
+      x.z = pChanges->a[i].zEName;
+      x.n = sqlite3Strlen30(x.z);
+      pChanges->a[i].pExpr =
+        sqlite3PExpr(pParse, TK_UPLUS, sqlite3ExprAlloc(db, TK_ID, &x, 0), 0);
+      if( db->mallocFailed ) goto update_cleanup;
+    }
+#endif
    u8 hCol = sqlite3StrIHash(pChanges->a[i].zEName);
    /* If this is an UPDATE with a FROM clause, do not resolve expressions
    ** here. The call to sqlite3Select() below will do that. */
@@ -190,7 +190,7 @@ void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
  va_list ap;
  sqlite3 *db = pParse->db;
  assert( db!=0 );
-  assert( db->pParse==pParse );
+  assert( db->pParse==pParse || db->pParse->pToplevel==pParse );
  db->errByteOffset = -2;
  va_start(ap, zFormat);
  zMsg = sqlite3VMPrintf(db, zFormat, ap);
@@ -390,6 +390,7 @@ end_of_vacuum:
  ** is closed by the DETACH.
  */
  db->autoCommit = 1;
+  assert( db->eConcurrent==0 );

  if( pDb ){
    sqlite3BtreeClose(pDb->pBt);
@@ -3613,6 +3613,7 @@ case OP_Savepoint: {
      ** is committed. 
      */
      int isTransaction = pSavepoint->pNext==0 && db->isTransactionSavepoint;
+      assert( db->eConcurrent==0 || db->isTransactionSavepoint==0 );
      if( isTransaction && p1==SAVEPOINT_RELEASE ){
        if( (rc = sqlite3VdbeCheckFk(p, 1))!=SQLITE_OK ){
          goto vdbe_return;
@@ -3699,23 +3700,31 @@ case OP_Savepoint: {
  break;
 }

-/* Opcode: AutoCommit P1 P2 * * *
+/* Opcode: AutoCommit P1 P2 P3 * *
 **
 ** Set the database auto-commit flag to P1 (1 or 0). If P2 is true, roll
 ** back any currently active btree transactions. If there are any active
 ** VMs (apart from this one), then a ROLLBACK fails.  A COMMIT fails if
 ** there are active writing VMs or active VMs that use shared cache.
 **
+** If P3 is non-zero, then this instruction is being executed as part of
+** a "BEGIN CONCURRENT" command.
+**
 ** This instruction causes the VM to halt.
 */
 case OP_AutoCommit: {
  int desiredAutoCommit;
  int iRollback;
+  int bConcurrent;
+  int hrc;

  desiredAutoCommit = pOp->p1;
  iRollback = pOp->p2;
+  bConcurrent = pOp->p3;
  assert( desiredAutoCommit==1 || desiredAutoCommit==0 );
  assert( desiredAutoCommit==1 || iRollback==0 );
+  assert( desiredAutoCommit==0 || bConcurrent==0 );
+  assert( db->autoCommit==0 || db->eConcurrent==CONCURRENT_NONE );
  assert( db->nVdbeActive>0 );  /* At least this one VM is active */
  assert( p->bIsReader );

@@ -3724,10 +3733,17 @@ case OP_AutoCommit: {
      assert( desiredAutoCommit==1 );
      sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
      db->autoCommit = 1;
-    }else if( desiredAutoCommit && db->nVdbeWrite>0 ){
-      /* If this instruction implements a COMMIT and other VMs are writing
-      ** return an error indicating that the other VMs must complete first. 
-      */
+      db->eConcurrent = CONCURRENT_NONE;
+    }else if( desiredAutoCommit
+            && (db->nVdbeWrite>0 || (db->eConcurrent && db->nVdbeActive>1)) ){
+      /* A transaction may only be committed if there are no other active
+      ** writer VMs. If the transaction is CONCURRENT, then it may only be
+      ** committed if there are no active VMs at all (readers or writers).
+      **
+      ** If this instruction is a COMMIT and the transaction may not be
+      ** committed due to one of the conditions above, return an error
+      ** indicating that other VMs must complete before the COMMIT can 
+      ** be processed.  */
      sqlite3VdbeError(p, "cannot commit transaction - "
                          "SQL statements in progress");
      rc = SQLITE_BUSY;
@@ -3737,12 +3753,16 @@ case OP_AutoCommit: {
    }else{
      db->autoCommit = (u8)desiredAutoCommit;
    }
-    if( sqlite3VdbeHalt(p)==SQLITE_BUSY ){
+    hrc = sqlite3VdbeHalt(p);
+    if( (hrc & 0xFF)==SQLITE_BUSY ){
      p->pc = (int)(pOp - aOp);
      db->autoCommit = (u8)(1-desiredAutoCommit);
-      p->rc = rc = SQLITE_BUSY;
+      p->rc = hrc;
+      rc = SQLITE_BUSY;
      goto vdbe_return;
    }
+    assert( bConcurrent==CONCURRENT_NONE || bConcurrent==CONCURRENT_OPEN );
+    db->eConcurrent = (u8)bConcurrent;
    sqlite3CloseSavepoints(db);
    if( p->rc==SQLITE_OK ){
      rc = SQLITE_DONE;
@@ -3955,6 +3975,17 @@ case OP_SetCookie: {
  pDb = &db->aDb[pOp->p1];
  assert( pDb->pBt!=0 );
  assert( sqlite3SchemaMutexHeld(db, pOp->p1, 0) );
+#ifndef SQLITE_OMIT_CONCURRENT
+  if( db->eConcurrent 
+   && (pOp->p2==BTREE_USER_VERSION || pOp->p2==BTREE_APPLICATION_ID)
+  ){
+    rc = SQLITE_ERROR;
+    sqlite3VdbeError(p, "cannot modify %s within CONCURRENT transaction",
+        pOp->p2==BTREE_USER_VERSION ? "user_version" : "application_id"
+    );
+    goto abort_due_to_error;
+  }
+#endif
  /* See note about index shifting on OP_ReadCookie */
  rc = sqlite3BtreeUpdateMeta(pDb->pBt, pOp->p2, pOp->p3);
  if( pOp->p2==BTREE_SCHEMA_VERSION ){
@@ -4104,6 +4135,11 @@ case OP_OpenWrite:
  pX = pDb->pBt;
  assert( pX!=0 );
  if( pOp->opcode==OP_OpenWrite ){
+#ifndef SQLITE_OMIT_CONCURRENT
+    if( db->eConcurrent==CONCURRENT_OPEN && p2==1 && iDb!=1 ){
+      db->eConcurrent = CONCURRENT_SCHEMA;
+    }
+#endif
    assert( OPFLAG_FORDELETE==BTREE_FORDELETE );
    wrFlag = BTREE_WRCSR | (pOp->p5 & OPFLAG_FORDELETE);
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
@@ -7738,6 +7774,11 @@ case OP_CursorUnlock: {
 */
 case OP_TableLock: {
  u8 isWriteLock = (u8)pOp->p3;
+#ifndef SQLITE_OMIT_CONCURRENT
+  if( isWriteLock && db->eConcurrent && pOp->p2==1 && pOp->p1!=1 ){
+    db->eConcurrent = CONCURRENT_SCHEMA;
+  }
+#endif
  if( isWriteLock || 0==(db->flags&SQLITE_ReadUncommit) ){
    int p1 = pOp->p1; 
    assert( p1>=0 && p1<db->nDb );
@@ -381,6 +381,7 @@ int sqlite3VdbeAddFunctionCall(
  addr = sqlite3VdbeAddOp4(v, eCallCtx ? OP_PureFunc : OP_Function,
                           p1, p2, p3, (char*)pCtx, P4_FUNCCTX);
  sqlite3VdbeChangeP5(v, eCallCtx & NC_SelfRef);
+  sqlite3MayAbort(pParse);
  return addr;
 }

@@ -716,6 +717,7 @@ int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
     || opcode==OP_VDestroy
     || opcode==OP_VCreate
     || opcode==OP_ParseSchema
+     || opcode==OP_Function || opcode==OP_PureFunc
     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
      && ((pOp->p1)!=SQLITE_OK && pOp->p2==OE_Abort))
    ){
@@ -2776,10 +2778,27 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
        assert( i!=1 );
        nTrans++;
      }
-      rc = sqlite3PagerExclusiveLock(pPager);
+      rc = sqlite3BtreeExclusiveLock(pBt);
      sqlite3BtreeLeave(pBt);
    }
  }
+
+#ifndef SQLITE_OMIT_CONCURRENT
+  if( db->eConcurrent && (rc & 0xFF)==SQLITE_BUSY ){
+    /* An SQLITE_BUSY or SQLITE_BUSY_SNAPSHOT was encountered while 
+    ** attempting to take the WRITER lock on a wal file. Release the
+    ** WRITER locks on all wal files and return early.  */
+    for(i=0; i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_WRITE ){
+        sqlite3BtreeEnter(pBt);
+        sqlite3PagerDropExclusiveLock(sqlite3BtreePager(pBt));
+        sqlite3BtreeLeave(pBt);
+      }
+    }
+  }
+#endif
+
  if( rc!=SQLITE_OK ){
    return rc;
  }
@@ -3181,6 +3200,7 @@ int sqlite3VdbeHalt(Vdbe *p){
          sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
          sqlite3CloseSavepoints(db);
          db->autoCommit = 1;
+          db->eConcurrent = CONCURRENT_NONE;
          p->nChange = 0;
        }
      }
@@ -3219,9 +3239,9 @@ int sqlite3VdbeHalt(Vdbe *p){
          ** is required. */
          rc = vdbeCommit(db, p);
        }
-        if( rc==SQLITE_BUSY && p->readOnly ){
+        if( (rc & 0xFF)==SQLITE_BUSY && p->readOnly ){
          sqlite3VdbeLeave(p);
-          return SQLITE_BUSY;
+          return rc;
        }else if( rc!=SQLITE_OK ){
          p->rc = rc;
          sqlite3RollbackAll(db, SQLITE_OK);
@@ -3246,6 +3266,7 @@ int sqlite3VdbeHalt(Vdbe *p){
        sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
        sqlite3CloseSavepoints(db);
        db->autoCommit = 1;
+        db->eConcurrent = CONCURRENT_NONE;
        p->nChange = 0;
      }
    }
@@ -3267,6 +3288,7 @@ int sqlite3VdbeHalt(Vdbe *p){
        sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
        sqlite3CloseSavepoints(db);
        db->autoCommit = 1;
+        db->eConcurrent = CONCURRENT_NONE;
        p->nChange = 0;
      }
    }
@@ -526,8 +526,10 @@ struct Wal {
  WalIndexHdr hdr;           /* Wal-index header for current transaction */
  u32 minFrame;              /* Ignore wal frames before this one */
  u32 iReCksum;              /* On commit, recalculate checksums from here */
+  u32 nPriorFrame;           /* For sqlite3WalInfo() */
  const char *zWalName;      /* Name of WAL file */
  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
+  FastPrng sPrng;            /* Random number generator */
 #ifdef SQLITE_DEBUG
  u8 lockError;              /* True if a locking error has occurred */
 #endif
@@ -925,7 +927,7 @@ static const char *walLockName(int lockIdx){
 /*
 ** Set or release locks on the WAL.  Locks are either shared or exclusive.
 ** A lock cannot be moved directly between shared and exclusive - it must go
-** through the unlocked state first.
+** through the concurrent state first.
 **
 ** In locking_mode=EXCLUSIVE, all of these routines become no-ops.
 */
@@ -1228,7 +1230,7 @@ static int walIndexRecover(Wal *pWal){
  /* Obtain an exclusive lock on all byte in the locking range not already
  ** locked by the caller. The caller is guaranteed to have locked the
  ** WAL_WRITE_LOCK byte, and may have also locked the WAL_CKPT_LOCK byte.
-  ** If successful, the same bytes that are locked here are unlocked before
+  ** If successful, the same bytes that are locked here are concurrent before
  ** this function returns.
  */
  assert( pWal->ckptLock==1 || pWal->ckptLock==0 );
@@ -1546,6 +1548,7 @@ int sqlite3WalOpen(
  pRet->syncHeader = 1;
  pRet->padToSectorBoundary = 1;
  pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);
+  sqlite3FastPrngInit(&pRet->sPrng);

  /* Open file handle on the write-ahead log file. */
  flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
@@ -2183,7 +2186,7 @@ static int walCheckpoint(
      rc = SQLITE_BUSY;
    }else if( eMode>=SQLITE_CHECKPOINT_RESTART ){
      u32 salt1;
-      sqlite3_randomness(4, &salt1);
+      sqlite3FastRandomness(&pWal->sPrng, 4, &salt1);
      assert( pInfo->nBackfill==pWal->hdr.mxFrame );
      rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
      if( rc==SQLITE_OK ){
@@ -2299,6 +2302,49 @@ int sqlite3WalClose(
  return rc;
 }

+/*
+** Try to copy the wal-index header from shared-memory into (*pHdr). Return
+** zero if successful or non-zero otherwise. If the header is corrupted
+** (either because the two copies are inconsistent or because the checksum 
+** values are incorrect), the read fails and non-zero is returned.
+*/
+static int walIndexLoadHdr(Wal *pWal, WalIndexHdr *pHdr){
+  u32 aCksum[2];                  /* Checksum on the header content */
+  WalIndexHdr h2;                 /* Second copy of the header content */
+  WalIndexHdr volatile *aHdr;     /* Header in shared memory */
+
+  /* The first page of the wal-index must be mapped at this point. */
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+
+  /* Read the header. This might happen concurrently with a write to the
+  ** same area of shared memory on a different CPU in a SMP,
+  ** meaning it is possible that an inconsistent snapshot is read
+  ** from the file. If this happens, return non-zero.
+  **
+  ** There are two copies of the header at the beginning of the wal-index.
+  ** When reading, read [0] first then [1].  Writes are in the reverse order.
+  ** Memory barriers are used to prevent the compiler or the hardware from
+  ** reordering the reads and writes.
+  */
+  aHdr = walIndexHdr(pWal);
+  memcpy(pHdr, (void *)&aHdr[0], sizeof(h2));
+  walShmBarrier(pWal);
+  memcpy(&h2, (void *)&aHdr[1], sizeof(h2));
+
+  if( memcmp(&h2, pHdr, sizeof(h2))!=0 ){
+    return 1;   /* Dirty read */
+  }  
+  if( h2.isInit==0 ){
+    return 1;   /* Malformed header - probably all zeros */
+  }
+  walChecksumBytes(1, (u8*)&h2, sizeof(h2)-sizeof(h2.aCksum), 0, aCksum);
+  if( aCksum[0]!=h2.aCksum[0] || aCksum[1]!=h2.aCksum[1] ){
+    return 1;   /* Checksum does not match */
+  }
+
+  return 0;
+}
+
 /*
 ** Try to read the wal-index header.  Return 0 on success and 1 if
 ** there is a problem.
@@ -2317,43 +2363,10 @@ int sqlite3WalClose(
 ** is read successfully and the checksum verified, return zero.
 */
 static SQLITE_NO_TSAN int walIndexTryHdr(Wal *pWal, int *pChanged){
-  u32 aCksum[2];                  /* Checksum on the header content */
-  WalIndexHdr h1, h2;             /* Two copies of the header content */
-  WalIndexHdr volatile *aHdr;     /* Header in shared memory */
+  WalIndexHdr h1;                 /* Copy of the header content */

-  /* The first page of the wal-index must be mapped at this point. */
-  assert( pWal->nWiData>0 && pWal->apWiData[0] );
-
-  /* Read the header. This might happen concurrently with a write to the
-  ** same area of shared memory on a different CPU in a SMP,
-  ** meaning it is possible that an inconsistent snapshot is read
-  ** from the file. If this happens, return non-zero.
-  **
-  ** tag-20200519-1:
-  ** There are two copies of the header at the beginning of the wal-index.
-  ** When reading, read [0] first then [1].  Writes are in the reverse order.
-  ** Memory barriers are used to prevent the compiler or the hardware from
-  ** reordering the reads and writes.  TSAN and similar tools can sometimes
-  ** give false-positive warnings about these accesses because the tools do not
-  ** account for the double-read and the memory barrier. The use of mutexes
-  ** here would be problematic as the memory being accessed is potentially
-  ** shared among multiple processes and not all mutex implementions work
-  ** reliably in that environment.
-  */
-  aHdr = walIndexHdr(pWal);
-  memcpy(&h1, (void *)&aHdr[0], sizeof(h1)); /* Possible TSAN false-positive */
-  walShmBarrier(pWal);
-  memcpy(&h2, (void *)&aHdr[1], sizeof(h2));
-
-  if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
-    return 1;   /* Dirty read */
-  }  
-  if( h1.isInit==0 ){
-    return 1;   /* Malformed header - probably all zeros */
-  }
-  walChecksumBytes(1, (u8*)&h1, sizeof(h1)-sizeof(h1.aCksum), 0, aCksum);
-  if( aCksum[0]!=h1.aCksum[0] || aCksum[1]!=h1.aCksum[1] ){
-    return 1;   /* Checksum does not match */
+  if( walIndexLoadHdr(pWal, &h1) ){
+    return 1;
  }

  if( memcmp(&pWal->hdr, &h1, sizeof(WalIndexHdr)) ){
@@ -3051,6 +3064,7 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
  testcase( rc==SQLITE_PROTOCOL );
  testcase( rc==SQLITE_OK );

+  pWal->nPriorFrame = pWal->hdr.mxFrame;
 #ifdef SQLITE_ENABLE_SNAPSHOT
  if( rc==SQLITE_OK ){
    if( pSnapshot && memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
@@ -3156,8 +3170,7 @@ int sqlite3WalFindFrame(
    return SQLITE_OK;
  }

-  /* Search the hash table or tables for an entry matching page number
-  ** pgno. Each iteration of the following for() loop searches one
+  /* Each iteration of the following for() loop searches one
  ** hash table (each hash table indexes up to HASHTABLE_NPAGE frames).
  **
  ** This code might run concurrently to the code in walIndexAppend()
@@ -3263,6 +3276,35 @@ Pgno sqlite3WalDbsize(Wal *pWal){
  return 0;
 }

+/*
+** Take the WRITER lock on the WAL file. Return SQLITE_OK if successful,
+** or an SQLite error code otherwise. This routine does not invoke any
+** busy-handler callbacks, that is done at a higher level.
+*/
+static int walWriteLock(Wal *pWal){
+  int rc;
+
+  /* Cannot start a write transaction without first holding a read lock */
+  assert( pWal->readLock>=0 );
+  assert( pWal->writeLock==0 );
+  assert( pWal->iReCksum==0 );
+
+  /* If this is a read-only connection, obtaining a write-lock is not
+  ** possible. In this case return SQLITE_READONLY. Otherwise, attempt
+  ** to grab the WRITER lock. Set Wal.writeLock to true and return
+  ** SQLITE_OK if successful, or leave Wal.writeLock clear and return 
+  ** an SQLite error code (possibly SQLITE_BUSY) otherwise. */
+  if( pWal->readOnly ){
+    rc = SQLITE_READONLY;
+  }else{
+    rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    if( rc==SQLITE_OK ){
+      pWal->writeLock = 1;
+    }
+  }
+
+  return rc;
+}

 /* 
 ** This function starts a write transaction on the WAL.
@@ -3289,38 +3331,209 @@ int sqlite3WalBeginWriteTransaction(Wal *pWal){
    return SQLITE_OK;
  }
 #endif
-
-  /* Cannot start a write transaction without first holding a read
-  ** transaction. */
-  assert( pWal->readLock>=0 );
-  assert( pWal->writeLock==0 && pWal->iReCksum==0 );
-
-  if( pWal->readOnly ){
-    return SQLITE_READONLY;
+  
+  rc = walWriteLock(pWal);
+  if( rc==SQLITE_OK ){
+    /* If another connection has written to the database file since the
+    ** time the read transaction on this connection was started, then
+    ** the write is disallowed. Release the WRITER lock and return
+    ** SQLITE_BUSY_SNAPSHOT in this case.  */
+    if( memcmp(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr))!=0 ){
+      walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+      pWal->writeLock = 0;
+      rc = SQLITE_BUSY_SNAPSHOT;
+    }
  }
-
-  /* Only one writer allowed at a time.  Get the write lock.  Return
-  ** SQLITE_BUSY if unable.
-  */
-  rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
-  if( rc ){
-    return rc;
-  }
-  pWal->writeLock = 1;
-
-  /* If another connection has written to the database file since the
-  ** time the read transaction on this connection was started, then
-  ** the write is disallowed.
-  */
-  if( memcmp(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr))!=0 ){
-    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
-    pWal->writeLock = 0;
-    rc = SQLITE_BUSY_SNAPSHOT;
-  }
-
  return rc;
 }

+/*
+** This function is called by a writer that has a read-lock on aReadmark[0]
+** (pWal->readLock==0). This function relinquishes that lock and takes a
+** lock on a different aReadmark[] slot. 
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+static int walUpgradeReadlock(Wal *pWal){
+  int cnt;
+  int rc;
+  assert( pWal->writeLock && pWal->readLock==0 );
+  walUnlockShared(pWal, WAL_READ_LOCK(0));
+  pWal->readLock = -1;
+  cnt = 0;
+  do{
+    int notUsed;
+    rc = walTryBeginRead(pWal, &notUsed, 1, ++cnt);
+  }while( rc==WAL_RETRY );
+  assert( (rc&0xff)!=SQLITE_BUSY ); /* BUSY not possible when useWal==1 */
+  testcase( (rc&0xff)==SQLITE_IOERR );
+  testcase( rc==SQLITE_PROTOCOL );
+  testcase( rc==SQLITE_OK );
+  return rc;
+}
+
+
+#ifndef SQLITE_OMIT_CONCURRENT
+/* 
+** This function is only ever called when committing a "BEGIN CONCURRENT"
+** transaction. It may be assumed that no frames have been written to
+** the wal file. The second parameter is a pointer to the in-memory 
+** representation of page 1 of the database (which may or may not be
+** dirty). The third is a bitvec with a bit set for each page in the
+** database file that was read by the current concurrent transaction.
+**
+** This function performs three tasks:
+**
+**   1) It obtains the WRITER lock on the wal file,
+**
+**   2) It checks that there are no conflicts between the current
+**      transaction and any transactions committed to the wal file since
+**      it was opened, and
+**
+**   3) It ejects any non-dirty pages from the page-cache that have been
+**      written by another client since the CONCURRENT transaction was started
+**      (so as to avoid ending up with an inconsistent cache after the
+**      current transaction is committed).
+**
+** If no error occurs and the caller may proceed with committing the 
+** transaction, SQLITE_OK is returned. SQLITE_BUSY is returned if the WRITER
+** lock cannot be obtained. Or, if the WRITER lock can be obtained but there
+** are conflicts with a committed transaction, SQLITE_BUSY_SNAPSHOT. Finally,
+** if an error (i.e. an OOM condition or IO error), an SQLite error code
+** is returned.
+*/
+int sqlite3WalLockForCommit(
+  Wal *pWal, 
+  PgHdr *pPg1, 
+  Bitvec *pAllRead, 
+  Pgno *piConflict
+){
+  int rc = walWriteLock(pWal);
+
+  /* If the database has been modified since this transaction was started,
+  ** check if it is still possible to commit. The transaction can be 
+  ** committed if:
+  **
+  **   a) None of the pages in pList have been modified since the 
+  **      transaction opened, and
+  **
+  **   b) The database schema cookie has not been modified since the
+  **      transaction was started.
+  */
+  if( rc==SQLITE_OK ){
+    WalIndexHdr head;
+
+    if( walIndexLoadHdr(pWal, &head) ){
+      /* This branch is taken if the wal-index header is corrupted. This 
+      ** occurs if some other writer has crashed while committing a 
+      ** transaction to this database since the current concurrent transaction
+      ** was opened.  */
+      rc = SQLITE_BUSY_SNAPSHOT;
+    }else if( memcmp(&pWal->hdr, (void*)&head, sizeof(WalIndexHdr))!=0 ){
+      int iHash;
+      int iLast = walFramePage(head.mxFrame);
+      u32 iFirst = pWal->hdr.mxFrame+1;     /* First wal frame to check */
+      if( memcmp(pWal->hdr.aSalt, (u32*)head.aSalt, sizeof(u32)*2) ){
+        assert( pWal->readLock==0 );
+        iFirst = 1;
+      }
+      if( pPg1==0 ){
+        /* If pPg1==0, then the current transaction modified the database
+        ** schema. This means it conflicts with all other transactions. */
+        *piConflict = 1;
+        rc = SQLITE_BUSY_SNAPSHOT;
+      }
+      for(iHash=walFramePage(iFirst); rc==SQLITE_OK && iHash<=iLast; iHash++){
+        WalHashLoc sLoc;
+
+        rc = walHashGet(pWal, iHash, &sLoc);
+        if( rc==SQLITE_OK ){
+          u32 i, iMin, iMax;
+          assert( head.mxFrame>=sLoc.iZero );
+          iMin = (sLoc.iZero >= iFirst) ? 1 : (iFirst - sLoc.iZero);
+          iMax = (iHash==0) ? HASHTABLE_NPAGE_ONE : HASHTABLE_NPAGE;
+          if( iMax>(head.mxFrame-sLoc.iZero) ) iMax = (head.mxFrame-sLoc.iZero);
+          for(i=iMin; rc==SQLITE_OK && i<=iMax; i++){
+            PgHdr *pPg;
+            if( sLoc.aPgno[i-1]==1 ){
+              /* Check that the schema cookie has not been modified. If
+              ** it has not, the commit can proceed. */
+              u8 aNew[4];
+              u8 *aOld = &((u8*)pPg1->pData)[40];
+              int sz;
+              i64 iOffset;
+              sz = pWal->hdr.szPage;
+              sz = (sz&0xfe00) + ((sz&0x0001)<<16);
+              iOffset = walFrameOffset(i+sLoc.iZero, sz) + WAL_FRAME_HDRSIZE+40;
+              rc = sqlite3OsRead(pWal->pWalFd, aNew, sizeof(aNew), iOffset);
+              if( rc==SQLITE_OK && memcmp(aOld, aNew, sizeof(aNew)) ){
+                rc = SQLITE_BUSY_SNAPSHOT;
+              }
+            }else if( sqlite3BitvecTestNotNull(pAllRead, sLoc.aPgno[i-1]) ){
+              *piConflict = sLoc.aPgno[i-1];
+              rc = SQLITE_BUSY_SNAPSHOT;
+            }else
+            if( (pPg = sqlite3PagerLookup(pPg1->pPager, sLoc.aPgno[i-1])) ){
+              /* Page aPgno[i-1], which is present in the pager cache, has been
+              ** modified since the current CONCURRENT transaction was started.
+              ** However it was not read by the current transaction, so is not
+              ** a conflict. There are two possibilities: (a) the page was
+              ** allocated at the of the file by the current transaction or 
+              ** (b) was present in the cache at the start of the transaction.
+              **
+              ** For case (a), do nothing. This page will be moved within the
+              ** database file by the commit code to avoid the conflict. The
+              ** call to PagerUnref() is to release the reference grabbed by
+              ** the sqlite3PagerLookup() above.  
+              **
+              ** In case (b), drop the page from the cache - otherwise
+              ** following the snapshot upgrade the cache would be inconsistent
+              ** with the database as stored on disk. */
+              if( sqlite3PagerIswriteable(pPg) ){
+                sqlite3PagerUnref(pPg);
+              }else{
+                sqlite3PcacheDrop(pPg);
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  pWal->nPriorFrame = pWal->hdr.mxFrame;
+  return rc;
+}
+
+/* !defined(SQLITE_OMIT_CONCURRENT)
+**
+** This function is called as part of committing an CONCURRENT transaction.
+** It is assumed that sqlite3WalLockForCommit() has already been successfully
+** called and so (a) the WRITER lock is held and (b) it is known that the
+** wal-index-header stored in shared memory is not corrupt.
+**
+** Before returning, this function upgrades the client so that it is 
+** operating on the database snapshot currently at the head of the wal file
+** (even if the CONCURRENT transaction ran against an older snapshot).
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise.
+*/
+int sqlite3WalUpgradeSnapshot(Wal *pWal){
+  int rc = SQLITE_OK;
+  assert( pWal->writeLock );
+  memcpy(&pWal->hdr, (void*)walIndexHdr(pWal), sizeof(WalIndexHdr));
+
+  /* If this client has its read-lock on slot aReadmark[0] and the entire
+  ** wal has not been checkpointed, switch it to a different slot. Otherwise
+  ** any reads performed between now and committing the transaction will
+  ** read from the old snapshot - not the one just upgraded to.  */
+  if( pWal->readLock==0 && pWal->hdr.mxFrame!=walCkptInfo(pWal)->nBackfill ){
+    rc = walUpgradeReadlock(pWal);
+  }
+  return rc;
+}
+#endif   /* SQLITE_OMIT_CONCURRENT */
+
 /*
 ** End a write transaction.  The commit has already been done.  This
 ** routine merely releases the lock.
@@ -3347,9 +3560,14 @@ int sqlite3WalEndWriteTransaction(Wal *pWal){
 ** Otherwise, if the callback function does not return an error, this
 ** function returns SQLITE_OK.
 */
-int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
+int sqlite3WalUndo(
+  Wal *pWal, 
+  int (*xUndo)(void *, Pgno), 
+  void *pUndoCtx,
+  int bConcurrent                 /* True if this is a CONCURRENT transaction */
+){
  int rc = SQLITE_OK;
-  if( ALWAYS(pWal->writeLock) ){
+  if( pWal->writeLock ){
    Pgno iMax = pWal->hdr.mxFrame;
    Pgno iFrame;
  
@@ -3357,6 +3575,13 @@ int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
    ** was in before the client began writing to the database. 
    */
    memcpy(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr));
+#ifndef SQLITE_OMIT_CONCURRENT
+    if( bConcurrent ){
+      pWal->hdr.aCksum[0]++;
+    }
+#else
+    UNUSED_PARAMETER(bConcurrent);
+#endif

    for(iFrame=pWal->hdr.mxFrame+1; 
        ALWAYS(rc==SQLITE_OK) && iFrame<=iMax; 
@@ -3388,7 +3613,6 @@ int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
 ** point in the event of a savepoint rollback (via WalSavepointUndo()).
 */
 void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData){
-  assert( pWal->writeLock );
  aWalData[0] = pWal->hdr.mxFrame;
  aWalData[1] = pWal->hdr.aFrameCksum[0];
  aWalData[2] = pWal->hdr.aFrameCksum[1];
@@ -3404,7 +3628,7 @@ void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData){
 int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
  int rc = SQLITE_OK;

-  assert( pWal->writeLock );
+  assert( pWal->writeLock || aWalData[0]==pWal->hdr.mxFrame );
  assert( aWalData[3]!=pWal->nCkpt || aWalData[0]<=pWal->hdr.mxFrame );

  if( aWalData[3]!=pWal->nCkpt ){
@@ -3440,14 +3664,13 @@ int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
 */
 static int walRestartLog(Wal *pWal){
  int rc = SQLITE_OK;
-  int cnt;

  if( pWal->readLock==0 ){
    volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
    assert( pInfo->nBackfill==pWal->hdr.mxFrame );
    if( pInfo->nBackfill>0 ){
      u32 salt1;
-      sqlite3_randomness(4, &salt1);
+      sqlite3FastRandomness(&pWal->sPrng, 4, &salt1);
      rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
      if( rc==SQLITE_OK ){
        /* If all readers are using WAL_READ_LOCK(0) (in other words if no
@@ -3461,21 +3684,21 @@ static int walRestartLog(Wal *pWal){
        ** to handle if this transaction is rolled back.  */
        walRestartHdr(pWal, salt1);
        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+        pWal->nPriorFrame = 0;
      }else if( rc!=SQLITE_BUSY ){
        return rc;
      }
    }
-    walUnlockShared(pWal, WAL_READ_LOCK(0));
-    pWal->readLock = -1;
-    cnt = 0;
-    do{
-      int notUsed;
-      rc = walTryBeginRead(pWal, &notUsed, 1, ++cnt);
-    }while( rc==WAL_RETRY );
-    assert( (rc&0xff)!=SQLITE_BUSY ); /* BUSY not possible when useWal==1 */
-    testcase( (rc&0xff)==SQLITE_IOERR );
-    testcase( rc==SQLITE_PROTOCOL );
-    testcase( rc==SQLITE_OK );
+
+    /* Regardless of whether or not the wal file was restarted, change the
+    ** read-lock held by this client to a slot other than aReadmark[0]. 
+    ** Clients with a lock on aReadmark[0] read from the database file 
+    ** only - never from the wal file. This means that if a writer holding
+    ** a lock on aReadmark[0] were to commit a transaction but not close the
+    ** read-transaction, subsequent read operations would read directly from
+    ** the database file - ignoring the new pages just appended
+    ** to the wal file. */
+    rc = walUpgradeReadlock(pWal);
  }
  return rc;
 }
@@ -3659,7 +3882,7 @@ int sqlite3WalFrames(
    sqlite3Put4byte(&aWalHdr[4], WAL_MAX_VERSION);
    sqlite3Put4byte(&aWalHdr[8], szPage);
    sqlite3Put4byte(&aWalHdr[12], pWal->nCkpt);
-    if( pWal->nCkpt==0 ) sqlite3_randomness(8, pWal->hdr.aSalt);
+    if( pWal->nCkpt==0 ) sqlite3FastRandomness(&pWal->sPrng, 8, pWal->hdr.aSalt);
    memcpy(&aWalHdr[16], pWal->hdr.aSalt, 8);
    walChecksumBytes(1, aWalHdr, WAL_HDRSIZE-2*4, 0, aCksum);
    sqlite3Put4byte(&aWalHdr[24], aCksum[0]);
@@ -3736,6 +3959,7 @@ int sqlite3WalFrames(
    p->flags |= PGHDR_WAL_APPEND;
  }

+
  /* Recalculate checksums within the wal file if required. */
  if( isCommit && pWal->iReCksum ){
    rc = walRewriteChecksums(pWal, iFrame);
@@ -3919,7 +4143,6 @@ int sqlite3WalCheckpoint(

  /* Copy data from the log to the database file. */
  if( rc==SQLITE_OK ){
-
    if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
      rc = SQLITE_CORRUPT_BKPT;
    }else{
@@ -4152,4 +4375,16 @@ sqlite3_file *sqlite3WalFile(Wal *pWal){
  return pWal->pWalFd;
 }

+/* 
+** Return the values required by sqlite3_wal_info().
+*/
+int sqlite3WalInfo(Wal *pWal, u32 *pnPrior, u32 *pnFrame){
+  int rc = SQLITE_OK;
+  if( pWal ){
+    *pnFrame = pWal->hdr.mxFrame;
+    *pnPrior = pWal->nPriorFrame;
+  }
+  return rc;
+}
+
 #endif /* #ifndef SQLITE_OMIT_WAL */
@@ -34,7 +34,7 @@
 # define sqlite3WalDbsize(y)                     0
 # define sqlite3WalBeginWriteTransaction(y)      0
 # define sqlite3WalEndWriteTransaction(x)        0
-# define sqlite3WalUndo(x,y,z)                   0
+# define sqlite3WalUndo(w,x,y,z)                 0
 # define sqlite3WalSavepoint(y,z)
 # define sqlite3WalSavepointUndo(y,z)            0
 # define sqlite3WalFrames(u,v,w,x,y,z)           0
@@ -83,7 +83,7 @@ int sqlite3WalBeginWriteTransaction(Wal *pWal);
 int sqlite3WalEndWriteTransaction(Wal *pWal);

 /* Undo any frames written (but not committed) to the log */
-int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx);
+int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx, int);

 /* Return an integer that records the current (uncommitted) write
 ** position in the WAL */
@@ -136,6 +136,15 @@ int sqlite3WalSnapshotCheck(Wal *pWal, sqlite3_snapshot *pSnapshot);
 void sqlite3WalSnapshotUnlock(Wal *pWal);
 #endif

+#ifndef SQLITE_OMIT_CONCURRENT
+/* Tell the wal layer that we want to commit a concurrent transaction */
+int sqlite3WalLockForCommit(Wal *pWal, PgHdr *pPg, Bitvec *pRead, Pgno*);
+
+/* Upgrade the state of the client to take into account changes written
+** by other connections */
+int sqlite3WalUpgradeSnapshot(Wal *pWal);
+#endif /* SQLITE_OMIT_CONCURRENT */
+
 #ifdef SQLITE_ENABLE_ZIPVFS
 /* If the WAL file is not empty, return the number of bytes of content
 ** stored in each frame (i.e. the db page-size when the WAL was created).
@@ -151,5 +160,8 @@ int sqlite3WalWriteLock(Wal *pWal, int bLock);
 void sqlite3WalDb(Wal *pWal, sqlite3 *db);
 #endif

+/* sqlite3_wal_info() data */
+int sqlite3WalInfo(Wal *pWal, u32 *pnPrior, u32 *pnFrame);
+
 #endif /* ifndef SQLITE_OMIT_WAL */
 #endif /* SQLITE_WAL_H */
@@ -1433,7 +1433,7 @@ static int whereKeyStats(
 #endif
  assert( pRec!=0 );
  assert( pIdx->nSample>0 );
-  assert( pRec->nField>0 && pRec->nField<=pIdx->nSampleCol );
+  assert( pRec->nField>0 );

  /* Do a binary search to find the first sample greater than or equal
  ** to pRec. If pRec contains a single field, the set of samples to search
@@ -1479,7 +1479,7 @@ static int whereKeyStats(
  ** it is extended to two fields. The duplicates that this creates do not 
  ** cause any problems.
  */
-  nField = pRec->nField;
+  nField = MIN(pRec->nField, pIdx->nSample);
  iCol = 0;
  iSample = pIdx->nSample * nField;
  do{
@@ -4168,6 +4168,7 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
  sqlite3 *db = pWInfo->pParse->db;
  int rc = SQLITE_OK;
  int bFirstPastRJ = 0;
+  int hasRightJoin = 0;
  WhereLoop *pNew;


@@ -4188,15 +4189,16 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
      ** prevents the right operand of a RIGHT JOIN from being swapped with
      ** other elements even further to the right.
      **
-      ** The JT_LTORJ term prevents any FROM-clause term reordering for terms
-      ** to the left of a RIGHT JOIN.  This is conservative.  Relaxing this
-      ** constraint somewhat to prevent terms from crossing from the right
-      ** side of a LEFT JOIN over to the left side when they are on the
-      ** left side of a RIGHT JOIN would be sufficient for all known failure
-      ** cases.  FIX ME: Implement this optimization.
+      ** The JT_LTORJ case and the hasRightJoin flag work together to
+      ** prevent FROM-clause terms from moving from the right side of
+      ** a LEFT JOIN over to the left side of that join if the LEFT JOIN
+      ** is itself on the left side of a RIGHT JOIN.
      */
+      if( pItem->fg.jointype & JT_LTORJ ) hasRightJoin = 1;
      mPrereq |= mPrior;
      bFirstPastRJ = (pItem->fg.jointype & JT_RIGHT)!=0;
+    }else if( !hasRightJoin ){
+      mPrereq = 0;
    }
 #ifndef SQLITE_OMIT_VIRTUALTABLE
    if( IsVirtual(pItem->pTab) ){
@@ -622,7 +622,8 @@ static int codeEqualityTerm(
        }
        sqlite3ExprDelete(db, pX);
      }else{
-        aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*nEq);
+        int n = sqlite3ExprVectorSize(pX->pLeft);
+        aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*MAX(nEq,n));
        eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, aiMap, &iTab);
      }
      pX = pExpr;
@@ -0,0 +1,556 @@
+/*
+** 2016-05-07
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+*/
+
+
+#include <sqlite3.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include "tt3_core.c"
+
+#ifdef USE_OSINST
+# include "../src/test_osinst.c"
+#else
+# define vfslog_time() 0
+#endif
+
+typedef struct Config Config;
+typedef struct ThreadCtx ThreadCtx;
+
+#define THREAD_TIME_INSERT   0
+#define THREAD_TIME_COMMIT   1
+#define THREAD_TIME_ROLLBACK 2
+#define THREAD_TIME_WRITER   3
+#define THREAD_TIME_CKPT     4
+
+struct ThreadCtx {
+  Config *pConfig;
+  Sqlite *pDb;
+  Error *pErr;
+  sqlite3_int64 aTime[5];
+};
+
+struct Config {
+  int nIPT;                       /* --inserts-per-transaction */
+  int nThread;                    /* --threads */
+  int nSecond;                    /* --seconds */
+  int bMutex;                     /* --mutex */
+  int nAutoCkpt;                  /* --autockpt */
+  int bRm;                        /* --rm */
+  int bClearCache;                /* --clear-cache */
+  int nMmap;                      /* mmap limit in MB */
+  char *zFile;
+  int bOsinst;                    /* True to use osinst */
+
+  ThreadCtx *aCtx;                /* Array of size nThread */
+
+  pthread_cond_t cond;
+  pthread_mutex_t mutex;
+  int nCondWait;                  /* Number of threads waiting on hCond */
+  sqlite3_vfs *pVfs;
+};
+
+
+typedef struct VfsWrapperFd VfsWrapperFd;
+struct VfsWrapperFd {
+  sqlite3_file base;              /* Base class */
+  int bWriter;                    /* True if holding shm WRITER lock */
+  int iTid;
+  Config *pConfig;
+  sqlite3_file *pFd;              /* Underlying file descriptor */
+};
+
+/* Methods of the wrapper VFS */
+static int vfsWrapOpen(sqlite3_vfs*, const char*, sqlite3_file*, int, int*);
+static int vfsWrapDelete(sqlite3_vfs*, const char*, int);
+static int vfsWrapAccess(sqlite3_vfs*, const char*, int, int*);
+static int vfsWrapFullPathname(sqlite3_vfs*, const char *, int, char*);
+static void *vfsWrapDlOpen(sqlite3_vfs*, const char*);
+static void vfsWrapDlError(sqlite3_vfs*, int, char*);
+static void (*vfsWrapDlSym(sqlite3_vfs*,void*, const char*))(void);
+static void vfsWrapDlClose(sqlite3_vfs*, void*);
+static int vfsWrapRandomness(sqlite3_vfs*, int, char*);
+static int vfsWrapSleep(sqlite3_vfs*, int);
+static int vfsWrapCurrentTime(sqlite3_vfs*, double*);
+static int vfsWrapGetLastError(sqlite3_vfs*, int, char*);
+static int vfsWrapCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*);
+static int vfsWrapSetSystemCall(sqlite3_vfs*, const char*, sqlite3_syscall_ptr);
+static sqlite3_syscall_ptr vfsWrapGetSystemCall(sqlite3_vfs*, const char*);
+static const char *vfsWrapNextSystemCall(sqlite3_vfs*, const char*);
+
+/* Methods of wrapper sqlite3_io_methods object (see vfsWrapOpen()) */
+static int vfsWrapClose(sqlite3_file*);
+static int vfsWrapRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
+static int vfsWrapWrite(sqlite3_file*, const void*, int iAmt, sqlite3_int64);
+static int vfsWrapTruncate(sqlite3_file*, sqlite3_int64 size);
+static int vfsWrapSync(sqlite3_file*, int flags);
+static int vfsWrapFileSize(sqlite3_file*, sqlite3_int64 *pSize);
+static int vfsWrapLock(sqlite3_file*, int);
+static int vfsWrapUnlock(sqlite3_file*, int);
+static int vfsWrapCheckReservedLock(sqlite3_file*, int *pResOut);
+static int vfsWrapFileControl(sqlite3_file*, int op, void *pArg);
+static int vfsWrapSectorSize(sqlite3_file*);
+static int vfsWrapDeviceCharacteristics(sqlite3_file*);
+static int vfsWrapShmMap(sqlite3_file*, int iPg, int, int, void volatile**);
+static int vfsWrapShmLock(sqlite3_file*, int offset, int n, int flags);
+static void vfsWrapShmBarrier(sqlite3_file*);
+static int vfsWrapShmUnmap(sqlite3_file*, int deleteFlag);
+static int vfsWrapFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **);
+static int vfsWrapUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);
+
+static int vfsWrapOpen(
+  sqlite3_vfs *pVfs, 
+  const char *zName, 
+  sqlite3_file *pFd, 
+  int flags, 
+  int *fout
+){
+  static sqlite3_io_methods methods = {
+    3,
+    vfsWrapClose, vfsWrapRead, vfsWrapWrite,
+    vfsWrapTruncate, vfsWrapSync, vfsWrapFileSize,
+    vfsWrapLock, vfsWrapUnlock, vfsWrapCheckReservedLock,
+    vfsWrapFileControl, vfsWrapSectorSize, vfsWrapDeviceCharacteristics,
+    vfsWrapShmMap, vfsWrapShmLock, vfsWrapShmBarrier,
+    vfsWrapShmUnmap, vfsWrapFetch, vfsWrapUnfetch
+  };
+
+  Config *pConfig = (Config*)pVfs->pAppData;
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  int rc;
+
+  memset(pWrapper, 0, sizeof(VfsWrapperFd));
+  if( flags & SQLITE_OPEN_MAIN_DB ){
+    pWrapper->iTid = (int)sqlite3_uri_int64(zName, "tid", 0);
+  }
+
+  pWrapper->pFd = (sqlite3_file*)&pWrapper[1];
+  pWrapper->pConfig = pConfig;
+  rc = pConfig->pVfs->xOpen(pConfig->pVfs, zName, pWrapper->pFd, flags, fout);
+  if( rc==SQLITE_OK ){
+    pWrapper->base.pMethods = &methods;
+  }
+  return rc;
+}
+
+static int vfsWrapDelete(sqlite3_vfs *pVfs, const char *a, int b){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xDelete(pConfig->pVfs, a, b);
+}
+static int vfsWrapAccess(sqlite3_vfs *pVfs, const char *a, int b, int *c){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xAccess(pConfig->pVfs, a, b, c);
+}
+static int vfsWrapFullPathname(sqlite3_vfs *pVfs, const char *a, int b, char*c){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xFullPathname(pConfig->pVfs, a, b, c);
+}
+static void *vfsWrapDlOpen(sqlite3_vfs *pVfs, const char *a){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xDlOpen(pConfig->pVfs, a);
+}
+static void vfsWrapDlError(sqlite3_vfs *pVfs, int a, char *b){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xDlError(pConfig->pVfs, a, b);
+}
+static void (*vfsWrapDlSym(sqlite3_vfs *pVfs, void *a, const char *b))(void){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xDlSym(pConfig->pVfs, a, b);
+}
+static void vfsWrapDlClose(sqlite3_vfs *pVfs, void *a){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xDlClose(pConfig->pVfs, a);
+}
+static int vfsWrapRandomness(sqlite3_vfs *pVfs, int a, char *b){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xRandomness(pConfig->pVfs, a, b);
+}
+static int vfsWrapSleep(sqlite3_vfs *pVfs, int a){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xSleep(pConfig->pVfs, a);
+}
+static int vfsWrapCurrentTime(sqlite3_vfs *pVfs, double *a){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xCurrentTime(pConfig->pVfs, a);
+}
+static int vfsWrapGetLastError(sqlite3_vfs *pVfs, int a, char *b){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xGetLastError(pConfig->pVfs, a, b);
+}
+static int vfsWrapCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *a){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xCurrentTimeInt64(pConfig->pVfs, a);
+}
+static int vfsWrapSetSystemCall(
+  sqlite3_vfs *pVfs, 
+  const char *a, 
+  sqlite3_syscall_ptr b
+){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xSetSystemCall(pConfig->pVfs, a, b);
+}
+static sqlite3_syscall_ptr vfsWrapGetSystemCall(
+  sqlite3_vfs *pVfs, 
+  const char *a
+){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xGetSystemCall(pConfig->pVfs, a);
+}
+static const char *vfsWrapNextSystemCall(sqlite3_vfs *pVfs, const char *a){
+  Config *pConfig = (Config*)pVfs->pAppData;
+  return pConfig->pVfs->xNextSystemCall(pConfig->pVfs, a);
+}
+
+static int vfsWrapClose(sqlite3_file *pFd){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  pWrapper->pFd->pMethods->xClose(pWrapper->pFd);
+  pWrapper->pFd = 0;
+  return SQLITE_OK;
+}
+static int vfsWrapRead(sqlite3_file *pFd, void *a, int b, sqlite3_int64 c){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xRead(pWrapper->pFd, a, b, c);
+}
+static int vfsWrapWrite(
+  sqlite3_file *pFd, 
+  const void *a, int b, 
+  sqlite3_int64 c
+){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xWrite(pWrapper->pFd, a, b, c);
+}
+static int vfsWrapTruncate(sqlite3_file *pFd, sqlite3_int64 a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xTruncate(pWrapper->pFd, a);
+}
+static int vfsWrapSync(sqlite3_file *pFd, int a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xSync(pWrapper->pFd, a);
+}
+static int vfsWrapFileSize(sqlite3_file *pFd, sqlite3_int64 *a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xFileSize(pWrapper->pFd, a);
+}
+static int vfsWrapLock(sqlite3_file *pFd, int a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xLock(pWrapper->pFd, a);
+}
+static int vfsWrapUnlock(sqlite3_file *pFd, int a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xUnlock(pWrapper->pFd, a);
+}
+static int vfsWrapCheckReservedLock(sqlite3_file *pFd, int *a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xCheckReservedLock(pWrapper->pFd, a);
+}
+static int vfsWrapFileControl(sqlite3_file *pFd, int a, void *b){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xFileControl(pWrapper->pFd, a, b);
+}
+static int vfsWrapSectorSize(sqlite3_file *pFd){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xSectorSize(pWrapper->pFd);
+}
+static int vfsWrapDeviceCharacteristics(sqlite3_file *pFd){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xDeviceCharacteristics(pWrapper->pFd);
+}
+static int vfsWrapShmMap(
+  sqlite3_file *pFd, 
+  int a, int b, int c, 
+  void volatile **d
+){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xShmMap(pWrapper->pFd, a, b, c, d);
+}
+static int vfsWrapShmLock(sqlite3_file *pFd, int offset, int n, int flags){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  Config *pConfig = pWrapper->pConfig;
+  int bMutex = 0;
+  int rc;
+
+  if(  (offset==0 && n==1)
+    && (flags & SQLITE_SHM_LOCK) && (flags & SQLITE_SHM_EXCLUSIVE)
+  ){
+    pthread_mutex_lock(&pConfig->mutex);
+    pWrapper->bWriter = 1;
+    bMutex = 1;
+    if( pWrapper->iTid ){
+      sqlite3_int64 t = vfslog_time();
+      pConfig->aCtx[pWrapper->iTid-1].aTime[THREAD_TIME_WRITER] -= t;
+    }
+  }
+
+  rc = pWrapper->pFd->pMethods->xShmLock(pWrapper->pFd, offset, n, flags);
+
+  if( (rc!=SQLITE_OK && bMutex)
+   || (offset==0 && (flags & SQLITE_SHM_UNLOCK) && pWrapper->bWriter)
+  ){
+    assert( pWrapper->bWriter );
+    pthread_mutex_unlock(&pConfig->mutex);
+    pWrapper->bWriter = 0;
+    if( pWrapper->iTid ){
+      sqlite3_int64 t = vfslog_time();
+      pConfig->aCtx[pWrapper->iTid-1].aTime[THREAD_TIME_WRITER] += t;
+    }
+  }
+
+  return rc;
+}
+static void vfsWrapShmBarrier(sqlite3_file *pFd){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xShmBarrier(pWrapper->pFd);
+}
+static int vfsWrapShmUnmap(sqlite3_file *pFd, int a){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xShmUnmap(pWrapper->pFd, a);
+}
+static int vfsWrapFetch(sqlite3_file *pFd, sqlite3_int64 a, int b, void **c){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xFetch(pWrapper->pFd, a, b, c);
+}
+static int vfsWrapUnfetch(sqlite3_file *pFd, sqlite3_int64 a, void *b){
+  VfsWrapperFd *pWrapper = (VfsWrapperFd*)pFd;
+  return pWrapper->pFd->pMethods->xUnfetch(pWrapper->pFd, a, b);
+}
+
+static void create_vfs(Config *pConfig){
+  static sqlite3_vfs vfs = {
+    3, 0, 0, 0, "wrapper", 0,
+    vfsWrapOpen, vfsWrapDelete, vfsWrapAccess,
+    vfsWrapFullPathname, vfsWrapDlOpen, vfsWrapDlError,
+    vfsWrapDlSym, vfsWrapDlClose, vfsWrapRandomness,
+    vfsWrapSleep, vfsWrapCurrentTime, vfsWrapGetLastError,
+    vfsWrapCurrentTimeInt64, vfsWrapSetSystemCall, vfsWrapGetSystemCall,
+    vfsWrapNextSystemCall
+  };
+  sqlite3_vfs *pVfs;
+
+  pVfs = sqlite3_vfs_find(0);
+  vfs.mxPathname = pVfs->mxPathname;
+  vfs.szOsFile = pVfs->szOsFile + sizeof(VfsWrapperFd);
+  vfs.pAppData = (void*)pConfig;
+  pConfig->pVfs = pVfs;
+
+  sqlite3_vfs_register(&vfs, 1);
+}
+
+
+/*
+** Wal hook used by connections in thread_main().
+*/
+static int thread_wal_hook(
+  void *pArg,                     /* Pointer to ThreadCtx object */
+  sqlite3 *db,
+  const char *zDb, 
+  int nFrame
+){
+  ThreadCtx *pCtx = (ThreadCtx*)pArg;
+  Config *pConfig = pCtx->pConfig;
+
+  if( pConfig->nAutoCkpt && nFrame>=pConfig->nAutoCkpt ){
+    pCtx->aTime[THREAD_TIME_CKPT] -= vfslog_time();
+    pthread_mutex_lock(&pConfig->mutex);
+    if( pConfig->nCondWait>=0 ){
+      pConfig->nCondWait++;
+      if( pConfig->nCondWait==pConfig->nThread ){
+        execsql(pCtx->pErr, pCtx->pDb, "PRAGMA wal_checkpoint");
+        pthread_cond_broadcast(&pConfig->cond);
+      }else{
+        pthread_cond_wait(&pConfig->cond, &pConfig->mutex);
+      }
+      pConfig->nCondWait--;
+    }
+    pthread_mutex_unlock(&pConfig->mutex);
+    pCtx->aTime[THREAD_TIME_CKPT] += vfslog_time();
+  }
+
+  return SQLITE_OK;
+}
+
+
+static char *thread_main(int iTid, void *pArg){
+  Config *pConfig = (Config*)pArg;
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  int nAttempt = 0;               /* Attempted transactions */
+  int nCommit = 0;                /* Successful transactions */
+  int j;
+  ThreadCtx *pCtx = &pConfig->aCtx[iTid-1];
+  char *zUri = 0;
+
+#ifdef USE_OSINST
+  char *zOsinstName = 0;
+  char *zLogName = 0;
+  if( pConfig->bOsinst ){
+    zOsinstName = sqlite3_mprintf("osinst%d", iTid);
+    zLogName = sqlite3_mprintf("bc_test1.log.%d.%d", (int)getpid(), iTid);
+    zUri = sqlite3_mprintf(
+        "file:%s?vfs=%s&tid=%d", pConfig->zFile, zOsinstName, iTid
+    );
+    sqlite3_vfslog_new(zOsinstName, 0, zLogName);
+    opendb(&err, &db, zUri, 0);
+  }else
+#endif
+  {
+    zUri = sqlite3_mprintf("file:%s?tid=%d", pConfig->zFile, iTid);
+    opendb(&err, &db, zUri, 0);
+  }
+
+  sqlite3_busy_handler(db.db, 0, 0);
+  sql_script_printf(&err, &db, 
+      "PRAGMA wal_autocheckpoint = 0;"
+      "PRAGMA synchronous = 0;"
+      "PRAGMA mmap_size = %lld;",
+      (i64)(pConfig->nMmap) * 1024 * 1024
+  );
+
+  pCtx->pConfig = pConfig;
+  pCtx->pErr = &err;
+  pCtx->pDb = &db;
+  sqlite3_wal_hook(db.db, thread_wal_hook, (void*)pCtx);
+
+  while( !timetostop(&err) ){
+    execsql(&err, &db, "BEGIN CONCURRENT");
+
+    pCtx->aTime[THREAD_TIME_INSERT] -= vfslog_time();
+    for(j=0; j<pConfig->nIPT; j++){
+      execsql(&err, &db, 
+          "INSERT INTO t1 VALUES"
+          "(randomblob(10), randomblob(20), randomblob(30), randomblob(200))"
+      );
+    }
+    pCtx->aTime[THREAD_TIME_INSERT] += vfslog_time();
+
+    pCtx->aTime[THREAD_TIME_COMMIT] -= vfslog_time();
+    execsql(&err, &db, "COMMIT");
+    pCtx->aTime[THREAD_TIME_COMMIT] += vfslog_time();
+
+    pCtx->aTime[THREAD_TIME_ROLLBACK] -= vfslog_time();
+    nAttempt++;
+    if( err.rc==SQLITE_OK ){
+      nCommit++;
+    }else{
+      clear_error(&err, SQLITE_BUSY);
+      execsql(&err, &db, "ROLLBACK");
+    }
+    pCtx->aTime[THREAD_TIME_ROLLBACK] += vfslog_time();
+
+    if( pConfig->bClearCache ){
+      sqlite3_db_release_memory(db.db);
+    }
+  }
+
+  closedb(&err, &db);
+
+#ifdef USE_OSINST
+  if( pConfig->bOsinst ){
+    sqlite3_vfslog_finalize(zOsinstName);
+    sqlite3_free(zOsinstName);
+    sqlite3_free(zLogName);
+  }
+#endif
+  sqlite3_free(zUri);
+
+  pthread_mutex_lock(&pConfig->mutex);
+  pConfig->nCondWait = -1;
+  pthread_cond_broadcast(&pConfig->cond);
+  pthread_mutex_unlock(&pConfig->mutex);
+
+  return sqlite3_mprintf("commits: %d/%d insert: %dms"
+      " commit: %dms"
+      " rollback: %dms" 
+      " writer: %dms"
+      " checkpoint: %dms", 
+      nCommit, nAttempt, 
+      (int)(pCtx->aTime[THREAD_TIME_INSERT]/1000), 
+      (int)(pCtx->aTime[THREAD_TIME_COMMIT]/1000), 
+      (int)(pCtx->aTime[THREAD_TIME_ROLLBACK]/1000),
+      (int)(pCtx->aTime[THREAD_TIME_WRITER]/1000),
+      (int)(pCtx->aTime[THREAD_TIME_CKPT]/1000)
+  );
+}
+
+int main(int argc, const char **argv){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  Threadset threads = {0};        /* Test threads */
+  Config conf = {5, 3, 5};
+  int i;
+
+  CmdlineArg apArg[] = {
+    { "-seconds", CMDLINE_INT,  offsetof(Config, nSecond) },
+    { "-inserts", CMDLINE_INT,  offsetof(Config, nIPT) },
+    { "-threads", CMDLINE_INT,  offsetof(Config, nThread) },
+    { "-mutex",   CMDLINE_BOOL, offsetof(Config, bMutex) },
+    { "-rm",      CMDLINE_BOOL, offsetof(Config, bRm) },
+    { "-autockpt",CMDLINE_INT,  offsetof(Config, nAutoCkpt) },
+    { "-mmap",    CMDLINE_INT,  offsetof(Config, nMmap) },
+    { "-clear-cache",    CMDLINE_BOOL,  offsetof(Config, bClearCache) },
+    { "-file",    CMDLINE_STRING,  offsetof(Config, zFile) },
+    { "-osinst",  CMDLINE_BOOL,  offsetof(Config, bOsinst) },
+    { 0, 0, 0 }
+  };
+
+  conf.nAutoCkpt = 1000;
+  cmdline_process(apArg, argc, argv, (void*)&conf);
+  if( err.rc==SQLITE_OK ){
+    char *z = cmdline_construct(apArg, (void*)&conf);
+    printf("With: %s\n", z);
+    sqlite3_free(z);
+  }
+  if( conf.zFile==0 ){
+    conf.zFile = "xyz.db";
+  }
+
+  /* Create the special VFS - "wrapper". And the mutex and condition 
+  ** variable. */
+  create_vfs(&conf);
+  pthread_mutex_init(&conf.mutex, 0);
+  pthread_cond_init(&conf.cond, 0);
+
+  conf.aCtx = sqlite3_malloc(sizeof(ThreadCtx) * conf.nThread);
+  memset(conf.aCtx, 0, sizeof(ThreadCtx) * conf.nThread);
+
+  /* Ensure the schema has been created */
+  opendb(&err, &db, conf.zFile, conf.bRm);
+  sql_script(&err, &db,
+      "PRAGMA journal_mode = wal;"
+      "CREATE TABLE IF NOT EXISTS t1(a PRIMARY KEY, b, c, d) WITHOUT ROWID;"
+      "CREATE INDEX IF NOT EXISTS t1b ON t1(b);"
+      "CREATE INDEX IF NOT EXISTS t1c ON t1(c);"
+  );
+
+  setstoptime(&err, conf.nSecond*1000);
+  if( conf.nThread==1 ){
+    char *z = thread_main(1, (void*)&conf);
+    printf("Thread 0 says: %s\n", (z==0 ? "..." : z));
+    fflush(stdout);
+  }else{
+    for(i=0; i<conf.nThread; i++){
+      launch_thread(&err, &threads, thread_main, (void*)&conf);
+    }
+    join_all_threads(&err, &threads);
+  }
+
+  if( err.rc==SQLITE_OK ){
+    printf("Database is %dK\n", (int)(filesize(&err, conf.zFile) / 1024));
+  }
+  if( err.rc==SQLITE_OK ){
+    char *zWal = sqlite3_mprintf("%s-wal", conf.zFile);
+    printf("Wal file is %dK\n", (int)(filesize(&err, zWal) / 1024));
+  }
+
+  closedb(&err, &db);
+  print_and_free_err(&err);
+  return 0;
+}
@@ -0,0 +1,127 @@
+# 2015 Aug 25
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# This file contains fault injection tests designed to test the concurrent
+# transactions feature.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/malloc_common.tcl
+set testprefix concfault
+
+# This test will not work with an in-memory journal, as the database will
+# become corrupt if an error is injected into a transaction after it starts
+# writing data out to the db file.
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+do_test 1-pre1 {
+  execsql {
+    PRAGMA journal_mode = wal;
+    CREATE TABLE t1(a PRIMARY KEY, b);
+    INSERT INTO t1 VALUES(randomblob(1000), randomblob(100));
+    INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+    INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+    INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+    INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+    DELETE FROM t1 WHERE rowid%2;
+  }
+  faultsim_save_and_close
+} {}
+
+do_faultsim_test 1.1 -prep {
+  faultsim_restore_and_reopen
+} -body {
+  execsql { 
+    BEGIN CONCURRENT;
+      INSERT INTO t1 VALUES(randomblob(1000), randomblob(100));
+    COMMIT;
+  }
+} -test {
+  faultsim_test_result {0 {}} 
+  catchsql { ROLLBACK }
+  faultsim_integrity_check
+}
+
+do_faultsim_test 1.2 -prep {
+  faultsim_restore_and_reopen
+} -body {
+  execsql { 
+    BEGIN CONCURRENT;
+      INSERT INTO t1 VALUES(randomblob(1000), randomblob(100));
+    ROLLBACK;
+  }
+} -test {
+  faultsim_test_result {0 {}} 
+  catchsql { ROLLBACK }
+  faultsim_integrity_check
+}
+
+do_faultsim_test 1.3 -prep {
+  faultsim_restore_and_reopen
+} -body {
+  execsql { 
+    BEGIN CONCURRENT;
+      DELETE FROM t1;
+    COMMIT;
+  }
+} -test {
+  faultsim_test_result {0 {}} 
+  catchsql { ROLLBACK }
+  faultsim_integrity_check
+}
+
+
+#-------------------------------------------------------------------------
+reset_db
+
+do_execsql_test 2.0 {
+  PRAGMA auto_vacuum = 0;
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(a PRIMARY KEY, b);
+  CREATE TABLE t2(a PRIMARY KEY, b);
+  INSERT INTO t1 VALUES(randomblob(1000), randomblob(100));
+  INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+  INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+  INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+  INSERT INTO t1 SELECT randomblob(1000), randomblob(1000) FROM t1;
+  DELETE FROM t1 WHERE rowid%2;
+} {wal}
+
+faultsim_save_and_close
+do_faultsim_test 1 -prep {
+  faultsim_restore_and_reopen
+  execsql {
+    SELECT * FROM t1;
+    BEGIN CONCURRENT;
+      INSERT INTO t2 VALUES(1, 2);
+  }
+  sqlite3 db2 test.db
+  execsql {
+    PRAGMA journal_size_limit = 10000;
+    INSERT INTO t1 VALUES(randomblob(1000), randomblob(1000));
+  } db2
+  db2 close
+} -body {
+  execsql { COMMIT }
+} -test {
+  faultsim_test_result {0 {}} 
+  catchsql { ROLLBACK }
+  set res [catchsql { SELECT count(*) FROM t1 }]
+  if {$res!="0 9"} { error "expected {0 9} got {$res}" }
+  faultsim_integrity_check
+}
+
+finish_test
+
@@ -0,0 +1,687 @@
+# 2015 July 26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+set ::testprefix concurrent
+
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  PRAGMA journal_mode = wal;
+} {wal}
+
+do_execsql_test 1.1 {
+  CREATE TABLE t1(k INTEGER PRIMARY KEY, v);
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES(1, 'abcd');
+  COMMIT;
+}
+
+do_execsql_test 1.2 {
+  SELECT * FROM t1;
+} {1 abcd}
+
+do_execsql_test 1.3 {
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES(2, 'efgh');
+  ROLLBACK;
+}
+
+do_execsql_test 1.4 {
+  SELECT * FROM t1;
+} {1 abcd}
+
+
+#-------------------------------------------------------------------------
+# CONCURRENT transactions cannot do cache spills.
+#
+foreach {tn trans spill} {
+  1 {BEGIN CONCURRENT}  0
+  2 {BEGIN}           1
+} {
+  do_test 1.5.$tn {
+    sqlite3 db2 test.db
+    set walsz [file size test.db-wal]
+
+    execsql { PRAGMA cache_size = 10 } db2
+    execsql $trans db2
+    execsql {
+      WITH cnt(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM cnt WHERE i<50)
+        INSERT INTO t1(v) SELECT randomblob(900) FROM cnt;
+    } db2
+
+    expr {[file size test.db-wal]==$walsz}
+  } [expr !$spill]
+
+  execsql ROLLBACK db2
+  db2 close
+}
+
+#-------------------------------------------------------------------------
+# CONCURRENT transactions man not be committed while there are active
+# readers.
+do_execsql_test 1.6.setup {
+  DROP TABLE t1;
+  CREATE TABLE t1(a, b);
+  INSERT INTO t1 VALUES(1, 2);
+  INSERT INTO t1 VALUES(3, 4);
+  INSERT INTO t1 VALUES(5, 6);
+}
+foreach {tn trans commit_ok} {
+  1 {BEGIN CONCURRENT}  0
+  2 {BEGIN}           1
+} {
+  do_test 1.6.$tn.1 {
+    set stmt [sqlite3_prepare db "SELECT * FROM t1" -1 dummy]
+    sqlite3_step $stmt
+  } SQLITE_ROW
+  do_test 1.6.$tn.2 {
+    execsql $trans
+    execsql { INSERT INTO t1 VALUES(7, 8) }
+  } {}
+
+  if { $commit_ok } {
+    do_test 1.6.$tn.3 { catchsql COMMIT } {0 {}}
+  } else {
+    do_test 1.6.$tn.4 { catchsql COMMIT } {/1 {cannot commit transaction .*}/}
+  }
+
+  sqlite3_finalize $stmt
+  catchsql ROLLBACK
+}
+
+#-------------------------------------------------------------------------
+# CONCURRENT transactions may not modify the db schema.
+#
+sqlite3 db2 test.db
+foreach {tn sql} {
+  1 { CREATE TABLE xx(a, b) }
+  2 { DROP TABLE t1 }
+  3 { CREATE INDEX i1 ON t1(a) }
+  4 { CREATE VIEW v1 AS SELECT * FROM t1 }
+} {
+  do_catchsql_test 1.7.0.$tn.1 "
+    BEGIN CONCURRENT;
+    $sql
+  " {0 {}}
+
+  db2 eval {INSERT INTO t1 DEFAULT VALUES}
+
+  do_catchsql_test 1.7.0.$tn.2 {
+    COMMIT
+  } {1 {database is locked}}
+
+  do_execsql_test 1.7.0.$tn.2 ROLLBACK
+
+  do_execsql_test 1.7.0.$tn.3 {
+    SELECT sql FROM sqlite_master;
+    SELECT sql FROM sqlite_temp_master;
+  } {{CREATE TABLE t1(a, b)}}
+
+  #do_execsql_test 1.7.0.$tn.3 COMMIT
+}
+
+# Except the temp db schema.
+foreach {tn sql} {
+  1 { CREATE TEMP TABLE xx(a, b) }
+  2 { DROP TABLE xx }
+  3 { CREATE TEMP TABLE yy(a, b) }
+  4 { CREATE VIEW temp.v1 AS SELECT * FROM t1 }
+  5 { CREATE INDEX yyi1 ON yy(a); }
+  6 { CREATE TABLE temp.zz(a, b) }
+} {
+  do_catchsql_test 1.7.1.$tn.1 "
+    BEGIN CONCURRENT;
+    $sql
+  " {0 {}}
+
+  do_execsql_test 1.7.1.$tn.2 COMMIT
+}
+
+
+do_execsql_test 1.7.1.x {
+  SELECT sql FROM sqlite_master;
+  SELECT sql FROM sqlite_temp_master;
+} {
+  {CREATE TABLE t1(a, b)}
+  {CREATE TABLE yy(a, b)} 
+  {CREATE VIEW v1 AS SELECT * FROM t1} 
+  {CREATE INDEX yyi1 ON yy(a)} 
+  {CREATE TABLE zz(a, b)}
+}
+
+#-------------------------------------------------------------------------
+# If an auto-vacuum database is written within an CONCURRENT transaction, it
+# is handled in the same way as for a non-CONCURRENT transaction.
+#
+reset_db
+do_execsql_test 1.8.1 {
+  PRAGMA auto_vacuum = 1;
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x, y);
+  INSERT INTO t1 VALUES('x', 'y');
+} {wal}
+
+do_execsql_test 1.8.2 {
+  BEGIN CONCURRENT;
+    SELECT * FROM t1;
+  COMMIT;
+} {x y}
+
+do_catchsql_test 1.8.3 {
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES('a', 'b');
+} {0 {}}
+
+do_test 1.8.4 {
+  sqlite3 db2 test.db
+  catchsql {
+    BEGIN CONCURRENT;
+      INSERT INTO t1 VALUES('c', 'd');
+  } db2
+} {1 {database is locked}}
+
+do_test 1.8.5 {
+  db eval COMMIT
+  db2 eval COMMIT
+} {}
+db close
+db2 close
+
+do_multiclient_test tn {
+
+  #-----------------------------------------------------------------------
+  # 1. Start an CONCURRENT transaction using [db1].
+  #
+  # 2. Start and then rollback a regular transaction using [db2]. This 
+  #    can be done as the ongoing [db1] transaction is CONCURRENT.
+  #
+  # 3. The [db1] transaction can now be committed, as [db2] has relinquished
+  #    the write lock.
+  #
+  do_test 2.$tn.1.1 {
+    sql1 { 
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(k INTEGER PRIMARY KEY, v);
+      INSERT INTO t1 VALUES(1, 'one');
+    }
+    sql1 { 
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(2, 'two');
+    }
+    code1 { sqlite3_get_autocommit db }
+  } 0
+
+  do_test 2.$tn.1.2 {
+    sql2 {
+      BEGIN;
+        INSERT INTO t1 VALUES(3, 'three');
+      ROLLBACK;
+    }
+  } {}
+
+  do_test 2.$tn.1.3 {
+    sql1 COMMIT
+    sql2 { SELECT * FROM t1 }
+  } {1 one 2 two}
+  
+  #-----------------------------------------------------------------------
+  # 1. Start an CONCURRENT transaction using [db1].
+  #
+  # 2. Commit a transaction using [db2].
+  #
+  # 3. Try to commit with [db1]. Check that SQLITE_BUSY_SNAPSHOT is returned,
+  #    and the transaction is not rolled back.
+  #
+  do_test 2.$tn.2.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(-1, 'hello world');
+    }
+  } {}
+
+  do_test 2.$tn.2.2 {
+    sql2 {
+      INSERT INTO t1 VALUES(3, 'three');
+    }
+  } {}
+
+  do_test 2.$tn.2.3.1 {
+    set rc [catch { sql1 COMMIT } msg]
+    list $rc $msg
+  } {1 {database is locked}}
+
+  do_test 2.$tn.2.3.2 {
+    code1 { list [sqlite3_extended_errcode db] [sqlite3_get_autocommit db] }
+  } {SQLITE_BUSY_SNAPSHOT 0}
+
+  do_test 2.$tn.2.3.3 {
+    sql1 {
+      SELECT * FROM t1;
+      ROLLBACK;
+    }
+  } {-1 {hello world} 1 one 2 two}
+  
+  #-----------------------------------------------------------------------
+  # 1. Start an CONCURRENT transaction using [db1].
+  #
+  # 2. Open a transaction using [db2].
+  #
+  # 3. Try to commit with [db1]. Check that SQLITE_BUSY is returned,
+  #    and the transaction is not rolled back.
+  #
+  # 4. Have [db2] roll its transaction back. Then check that [db1] can
+  #    commit.
+  #
+  do_test 2.$tn.3.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(4, 'four');
+    }
+  } {}
+
+  do_test 2.$tn.3.2 {
+    sql2 {
+      BEGIN;
+        INSERT INTO t1 VALUES(-1, 'xyz');
+    }
+  } {}
+
+  do_test 2.$tn.3.3.1 {
+    set rc [catch { sql1 COMMIT } msg]
+    list $rc $msg
+  } {1 {database is locked}}
+
+  do_test 2.$tn.3.3.2 {
+    code1 { list [sqlite3_extended_errcode db] [sqlite3_get_autocommit db] }
+  } {SQLITE_BUSY 0}
+
+  do_test 2.$tn.3.3.3 {
+    sql1 { SELECT * FROM t1; }
+  } {1 one 2 two 3 three 4 four}
+
+  do_test 2.$tn.3.4 {
+    sql2 ROLLBACK
+    sql1 COMMIT
+    sql1 { SELECT * FROM t1; }
+  } {1 one 2 two 3 three 4 four}
+
+  #-----------------------------------------------------------------------
+  # 1. Create a second table - t2.
+  #
+  # 2. Write to t1 with [db] and t2 with [db2].
+  #
+  # 3. See if it worked.
+  #
+  do_test 2.$tn.4.1 {
+    sql1 { CREATE TABLE t2(a, b) }
+  } {}
+  do_test 2.$tn.4.2 {
+    sql2 {
+      BEGIN CONCURRENT;
+        INSERT INTO t2 VALUES('i', 'n');
+    }
+
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(5, 'five');
+      COMMIT;
+    }
+
+    sql2 COMMIT
+  } {}
+
+  do_test 2.$tn.4.3.1 {
+    sql2 {SELECT * FROM t1}
+  } {1 one 2 two 3 three 4 four 5 five}
+  do_test 2.$tn.4.3.2 {
+    sql1 {SELECT * FROM t1}
+  } {1 one 2 two 3 three 4 four 5 five}
+
+  do_test 2.$tn.4.3.3 { sql2 {SELECT * FROM t2} } {i n}
+  do_test 2.$tn.4.3.4 { sql1 {SELECT * FROM t2} } {i n}
+
+  #-----------------------------------------------------------------------
+  # The "schema cookie" issue.
+  #
+  # 1. Begin and CONCURRENT write to "t1" using [db]
+  #
+  # 2. Create an index on t1 using [db2].
+  #
+  # 3. Attempt to commit the CONCURRENT write. This is an SQLITE_BUSY_SNAPSHOT,
+  #    even though there is no page collision.
+  #
+  do_test 2.$tn.5.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(6, 'six');
+    }
+  } {}
+
+  do_test 2.$tn.5.2 {
+    sql2 { CREATE INDEX i1 ON t1(v); }
+  } {}
+
+  do_test 2.$tn.5.3 {
+    list [catch { sql1 { COMMIT } } msg] $msg [sqlite3_errcode db]
+  } {1 {database is locked} SQLITE_BUSY_SNAPSHOT}
+
+  do_test 2.$tn.5.4 {
+    sql2 { PRAGMA integrity_check }
+  } {ok}
+  catch { sql1 ROLLBACK }
+
+  #-----------------------------------------------------------------------
+  #
+  # 1. Begin an CONCURRENT write to "t1" using [db]
+  #
+  # 2. Lots of inserts into t2. Enough to grow the db file and modify page 1.
+  #
+  # 3. Check that the CONCURRENT transaction can not be committed.
+  #
+  do_test 2.$tn.6.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(6, 'six');
+    }
+  } {}
+
+  do_test 2.$tn.6.2 {
+    sql2 { 
+      WITH src(a,b) AS (
+        VALUES(1,1) UNION ALL SELECT a+1,b+1 FROM src WHERE a<10000
+      ) INSERT INTO t2 SELECT * FROM src;
+    }
+  } {}
+
+  do_test 2.$tn.6.3 {
+    sql1 { SELECT count(*) FROM t2 }
+    list [catch { sql1 { COMMIT } } msg] $msg [sqlite3_errcode db]
+  } {1 {database is locked} SQLITE_BUSY_SNAPSHOT}
+  sql1 ROLLBACK
+
+  do_test 2.$tn.6.4 {
+    sql1 {
+      SELECT count(*) FROM t1;
+      SELECT count(*) FROM t2;
+    }
+  } {5 10001}
+
+  #-----------------------------------------------------------------------
+  # 
+  # 1. Begin an big CONCURRENT write to "t1" using [db] - large enough to
+  #    grow the db file.
+  #
+  # 2. Lots of inserts into t2. Also enough to grow the db file.
+  #
+  # 3. Check that the CONCURRENT transaction cannot be committed (due to a clash
+  #    on page 1 - the db size field).
+  #
+  do_test 2.$tn.7.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        WITH src(a,b) AS (
+          VALUES(10000,10000) UNION ALL SELECT a+1,b+1 FROM src WHERE a<20000
+        ) INSERT INTO t1 SELECT * FROM src;
+    }
+  } {}
+
+  do_test 2.$tn.7.2 {
+    sql2 { 
+      WITH src(a,b) AS (
+        VALUES(1,1) UNION ALL SELECT a+1,b+1 FROM src WHERE a<10000
+      ) INSERT INTO t2 SELECT * FROM src;
+    }
+  } {}
+
+  do_test 2.$tn.7.3 {
+    list [catch { sql1 { COMMIT } } msg] $msg [sqlite3_errcode db]
+  } {0 {} SQLITE_OK}
+
+  do_test 2.$tn.7.4 { sql3 { PRAGMA integrity_check } } ok
+}
+
+#-------------------------------------------------------------------------
+# Concurrent transactions may not modify the user_version or application_id.
+#
+reset_db
+do_execsql_test 3.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x, y);
+  INSERT INTO t1 VALUES('a', 'b');
+  PRAGMA user_version = 10;
+} {wal}
+do_execsql_test 3.1 {
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES('c', 'd');
+    SELECT * FROM t1;
+} {a b c d}
+do_catchsql_test 3.2 {
+  PRAGMA user_version = 11;
+} {1 {cannot modify user_version within CONCURRENT transaction}}
+do_execsql_test 3.3 {
+  PRAGMA user_version;
+  SELECT * FROM t1;
+} {10 a b c d}
+do_catchsql_test 3.4 {
+  PRAGMA application_id = 11;
+} {1 {cannot modify application_id within CONCURRENT transaction}}
+do_execsql_test 3.5 {
+  COMMIT;
+  PRAGMA user_version;
+  PRAGMA application_id;
+  SELECT * FROM t1;
+} {10 0 a b c d}
+
+#-------------------------------------------------------------------------
+# However, another transaction modifying the user_version or application_id
+# should not cause a conflict. And committing a concurrent transaction does not
+# clobber the modification - even if the concurrent transaction allocates or
+# frees database pages.
+#
+do_multiclient_test tn {
+  do_test 4.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE ttt(y UNIQUE, z UNIQUE);
+      PRAGMA user_version = 14;
+      BEGIN CONCURRENT;
+        INSERT INTO ttt VALUES('y', 'z');
+    }
+  } {wal}
+  do_test 4.$tn.2 {
+    sql2 { PRAGMA user_version = 16 }
+    sql1 COMMIT
+    sql1 { PRAGMA user_version }
+  } {16}
+
+  do_test 4.$tn.3 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO ttt VALUES(randomblob(10000), randomblob(4));
+        PRAGMA user_version;
+    }
+  } {16}
+  do_test 4.$tn.4 {
+    sql2 { PRAGMA user_version = 1234 }
+    sql1 {
+        PRAGMA user_version;
+      COMMIT;
+      PRAGMA user_version;
+      PRAGMA integrity_check;
+    }
+  } {16 1234 ok}
+
+  do_test 4.$tn.5 {
+    sql1 {
+      BEGIN CONCURRENT;
+        DELETE FROM ttt;
+        PRAGMA user_version;
+    }
+  } {1234}
+  do_test 4.$tn.4 {
+    sql2 { PRAGMA user_version = 5678 }
+    sql1 {
+        PRAGMA user_version;
+      COMMIT;
+      PRAGMA user_version;
+      PRAGMA integrity_check;
+    }
+  } {1234 5678 ok}
+}
+
+do_multiclient_test tn {
+  do_test 5.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE tt(a INTEGER PRIMARY KEY, b);
+      CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
+      INSERT INTO tt VALUES(1, randomblob(400));
+      BEGIN CONCURRENT;
+    }
+  } {wal}
+
+  do_test 5.$tn.2 {
+    sql1 { UPDATE t2 SET b=5 WHERE a=3 }
+    sql2 { INSERT INTO tt VALUES(2, randomblob(6000)) }
+  } {}
+
+  do_test 5.$tn.3 {
+    sql1 { COMMIT }
+  } {}
+}
+
+do_multiclient_test tn {
+  do_test 6.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
+      CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
+      INSERT INTO t1 VALUES(1, 'one');
+      INSERT INTO t2 VALUES(2, 'two');
+    }
+  } {wal}
+
+  do_test 6.$tn.2 {
+    sql2 {
+      BEGIN CONCURRENT;
+        SELECT * FROM t2;
+        INSERT INTO t1 VALUES(3, 'three');
+    }
+  } {2 two}
+
+  do_test 6.$tn.3 {
+    sql1 {
+      INSERT INTO t2 VALUES(3, 'three');
+    }
+  } {}
+
+  do_test 6.$tn.2 {
+    list [catch { sql2 { COMMIT } } msg] $msg
+  } {1 {database is locked}}
+}
+
+do_multiclient_test tn {
+  do_test 7.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
+      WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100) 
+      INSERT INTO t1 SELECT NULL, randomblob(400) FROM s;
+
+      CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
+      WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<50000) 
+      INSERT INTO t2 SELECT NULL, randomblob(400) FROM s;
+
+      CREATE TABLE t3(a INTEGER PRIMARY KEY, b);
+      WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100) 
+      INSERT INTO t3 SELECT NULL, randomblob(400) FROM s;
+
+      CREATE TABLE t4(a INTEGER PRIMARY KEY, b);
+
+    }
+    set {} {}
+  } {}
+
+  do_test 7.$tn.2 {
+    sql2 {
+      BEGIN CONCURRENT;
+        SELECT * FROM t1;
+        INSERT INTO t4 VALUES(1, 2);
+    }
+    set {} {}
+  } {}
+
+  do_test 7.$tn.3 {
+    sql3 {
+      BEGIN CONCURRENT;
+        SELECT * FROM t3;
+        INSERT INTO t4 VALUES(1, 2);
+    }
+    set {} {}
+  } {}
+
+  do_test 7.$tn.4 {
+    sql1 {
+      UPDATE t1 SET b=randomblob(400);
+      UPDATE t2 SET b=randomblob(400);
+      UPDATE t3 SET b=randomblob(400);
+    }
+  } {}
+
+  do_test 7.$tn.5 {
+    csql2 { COMMIT } 
+  } {1 {database is locked}}
+
+  do_test 7.$tn.6 {
+    csql3 { COMMIT } 
+  } {1 {database is locked}}
+
+
+  csql2 ROLLBACK
+  csql3 ROLLBACK
+
+  # The following test works with $tn==1 (sql2 and sql3 use separate 
+  # processes), but is quite slow. So only run it with $tn==2 (all
+  # connections in the same process).
+  #
+  if {$tn==2} {
+    do_test 7.$tn.7 {
+      for {set i 1} {$i < 10000} {incr i} {
+        sql3 { 
+          PRAGMA wal_checkpoint;
+          BEGIN CONCURRENT;
+          SELECT * FROM t3;
+          INSERT INTO t4 VALUES(1, 2);
+        }
+
+        sql1 {
+          UPDATE t2 SET b = randomblob(400) WHERE rowid <= $i;
+          UPDATE t3 SET b = randomblob(400) WHERE rowid = 1;
+        }
+
+        if {[csql3 COMMIT]!={1 {database is locked}}} {
+          error "Failed at i=$i"
+        }
+        csql3 ROLLBACK
+      }
+    } {}
+  }
+
+}
+
+finish_test
@@ -0,0 +1,626 @@
+# 2015 July 26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# Miscellaneous tests for transactions started with BEGIN CONCURRENT. 
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/wal_common.tcl
+set ::testprefix concurrent2
+
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+do_multiclient_test tn {
+
+  do_test 1.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(x);
+      CREATE TABLE t2(y);
+    }
+  } {wal}
+  do_test 1.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+
+  # Test that an CONCURRENT transaction that allocates/frees no pages does
+  # not conflict with a transaction that does allocate pages.
+  do_test 1.$tn.2  {
+    sql1 { 
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(4);
+    }
+    sql2 {
+      INSERT INTO t2 VALUES(randomblob(1500));
+    }
+    sql1 {
+      COMMIT;
+    }
+  } {}
+  do_test 1.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+  
+  # But that an CONCURRENT transaction does conflict with a transaction
+  # that modifies the db schema.
+  do_test 1.$tn.3  {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(5);
+    }
+    sql2 {
+      CREATE TABLE t3(z);
+    }
+    list [catch { sql1 COMMIT } msg] $msg
+  } {1 {database is locked}}
+  do_test 1.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+  
+  # Test that an CONCURRENT transaction that allocates at least one page 
+  # does not conflict with a transaction that allocates no pages.
+  do_test 1.$tn.4  {
+    sql1 { 
+      ROLLBACK;
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(randomblob(1500));
+    }
+    sql2 {
+      INSERT INTO t2 VALUES(8);
+    }
+    sql1 {
+      COMMIT;
+    }
+  } {}
+
+  do_test 1.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+}
+
+do_multiclient_test tn {
+  do_test 2.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(x UNIQUE);
+      CREATE TABLE t2(y UNIQUE);
+    }
+  } {wal}
+
+  do_test 2.$tn.2  {
+    sql1 { 
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(randomblob(1500));
+    }
+    sql2 {
+      INSERT INTO t2 VALUES(randomblob(1500));
+    }
+    sql1 COMMIT
+  } {}
+
+  do_test 2.$tn.3 { sql3 { PRAGMA integrity_check } } {ok}
+
+  do_test 2.$tn.4  {
+    sql1 { 
+      BEGIN CONCURRENT;
+        DELETE FROM t1;
+    }
+    sql2 {
+      DELETE FROM t2;
+    }
+    sql1 COMMIT
+  } {}
+
+  do_test 2.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+
+  do_test 2.$tn.6 {
+    sql1 {
+      INSERT INTO t1 VALUES(randomblob(1500));
+      INSERT INTO t1 VALUES(randomblob(1500));
+      INSERT INTO t2 VALUES(randomblob(1500));
+      DELETE FROM t1 WHERE rowid=1;
+    }
+
+    sql1 {
+      BEGIN CONCURRENT;
+        DELETE FROM t1 WHERE rowid=2;
+    }
+
+    sql2 {
+      DELETE FROM t2;
+    }
+
+    sql1 COMMIT
+  } {}
+
+  do_test 2.$tn.7 { sql3 { PRAGMA integrity_check } } {ok}
+}
+
+#-------------------------------------------------------------------------
+# When an CONCURRENT transaction is opened on a database, the nFree and 
+# iTrunk header fields of the cached version of page 1 are both set 
+# to 0. This allows an CONCURRENT transaction to use its own private 
+# free-page-list, which is merged with the main database free-list when
+# the transaction is committed.
+#
+# The following tests check that nFree/iTrunk are correctly restored if
+# an CONCURRENT transaction is rolled back, and that savepoint rollbacks
+# that occur within CONCURRENT transactions do not incorrectly restore
+# these fields to their on-disk values.
+#
+reset_db
+do_execsql_test 3.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x, y);
+  INSERT INTO t1 VALUES(randomblob(1500), randomblob(1500));
+  DELETE FROM t1;
+} {wal}
+
+do_execsql_test 3.1 {
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES(1, 2);
+  ROLLBACK;
+}
+
+do_execsql_test 3.2 { PRAGMA integrity_check } {ok}
+do_execsql_test 3.3 { PRAGMA freelist_count } {2}
+
+do_execsql_test 3.4.1 {
+  BEGIN CONCURRENT;
+    PRAGMA freelist_count;
+} {2}
+do_execsql_test 3.4.2 {
+  SAVEPOINT xyz;
+    INSERT INTO t1 VALUES(randomblob(1500), NULL);
+    PRAGMA freelist_count;
+} {0}
+do_execsql_test 3.4.3 {
+  ROLLBACK TO xyz;
+} {}
+do_execsql_test 3.4.4 { PRAGMA freelist_count } {0}
+do_execsql_test 3.4.5 { COMMIT; PRAGMA freelist_count } {2}
+do_execsql_test 3.4.6 { PRAGMA integrity_check } {ok}
+
+do_execsql_test 3.5.1 {
+  BEGIN CONCURRENT;
+    UPDATE t1 SET x=randomblob(10) WHERE y=555;
+    PRAGMA freelist_count;
+} {0}
+do_execsql_test 3.5.2 {
+  ROLLBACK;
+  PRAGMA freelist_count;
+} {2}
+do_execsql_test 3.5.3 { PRAGMA integrity_check } {ok}
+
+#-------------------------------------------------------------------------
+# Test that nothing goes wrong if an CONCURRENT transaction allocates a
+# page at the end of the file, frees it within the same transaction, and
+# then has to move the same page to avoid a conflict on COMMIT.
+#
+do_multiclient_test tn {
+  do_test 4.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(x);
+      CREATE TABLE t2(x);
+    }
+  } {wal}
+
+  do_test 4.$tn.2 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(randomblob(1500));
+        INSERT INTO t1 VALUES(randomblob(1500));
+        DELETE FROM t1 WHERE rowid = 1;
+    }
+
+    sql2 {
+      INSERT INTO t2 VALUES(randomblob(1500));
+      INSERT INTO t2 VALUES(randomblob(1500));
+      INSERT INTO t2 VALUES(randomblob(1500));
+      INSERT INTO t2 VALUES(randomblob(1500));
+      DELETE FROM t2 WHERE rowid IN (1, 2);
+    }
+
+    sql1 COMMIT
+  } {}
+}
+
+#-------------------------------------------------------------------------
+#
+do_multiclient_test tn {
+  do_test 5.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(x);
+      CREATE TABLE t2(x);
+      INSERT INTO t1 VALUES(randomblob(1500));
+      PRAGMA page_count;
+    }
+  } {wal 4}
+
+  do_test 5.$tn.2 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t2 VALUES(randomblob(1500));
+        PRAGMA page_count;
+    }
+  } {5}
+
+  do_test 5.$tn.3 {
+    sql2 { 
+      DELETE FROM t1;
+      PRAGMA freelist_count;
+      PRAGMA page_count;
+    }
+  } {1 4}
+
+  do_test 5.$tn.4 { sql1 COMMIT } {}
+  do_test 5.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+}
+
+#-------------------------------------------------------------------------
+#
+do_multiclient_test tn {
+  do_test 6.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(x);
+      INSERT INTO t1 VALUES(randomblob(1500));
+      PRAGMA wal_checkpoint;
+    }
+  } {wal 0 5 5}
+
+  do_test 6.$tn.2 {
+    sql1 { 
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(randomblob(1500));
+        INSERT INTO t1 VALUES(randomblob(1500));
+    }
+  } {}
+
+  do_test 6.$tn.3 {
+    sql2 {
+      BEGIN;
+        INSERT INTO t1 VALUES(randomblob(1500));
+        INSERT INTO t1 VALUES(randomblob(1500));
+      COMMIT;
+    }
+  } {}
+
+  do_test 6.$tn.4 { 
+    list [catch { sql1 COMMIT } msg] $msg
+  } {1 {database is locked}}
+  do_test 6.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}
+  do_test 6.$tn.5 { sql3 { SELECT count(*) from t1 } } {3}
+}
+
+#-------------------------------------------------------------------------
+# Test that if a corrupt wal-index-header is encountered when attempting
+# to commit a CONCURRENT transaction, the transaction is not committed
+# (or rolled back) and that SQLITE_BUSY_SNAPSHOT is returned to the user.
+#
+catch { db close }
+forcedelete test.db
+testvfs tvfs
+sqlite3 db test.db -vfs tvfs
+do_execsql_test 7.1 {
+  PRAGMA journal_mode = wal;
+  BEGIN;
+    CREATE TABLE t1(a, b, PRIMARY KEY(a));
+    INSERT INTO t1 VALUES(1, 2);
+    INSERT INTO t1 VALUES(3, 4);
+  COMMIT;
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES(5, 6);
+    INSERT INTO t1 VALUES(7, 8);
+    SELECT * FROM t1;
+} {wal 1 2 3 4 5 6 7 8}
+
+# Corrupt the wal-index header
+incr_tvfs_hdr test.db 11 1
+
+do_catchsql_test 7.2.1 { COMMIT } {1 {database is locked}}
+do_test 7.2.2 { sqlite3_extended_errcode db } SQLITE_BUSY_SNAPSHOT
+
+do_execsql_test 7.3.1 {
+  SELECT * FROM t1;
+  ROLLBACK;
+} {1 2 3 4 5 6 7 8}
+do_execsql_test 7.3.2 {
+  SELECT * FROM t1;
+} {1 2 3 4}
+
+#-------------------------------------------------------------------------
+# Test that "PRAGMA integrity_check" works within a concurrent 
+# transaction. Within a concurrent transaction, "PRAGMA integrity_check"
+# is unable to detect unused database pages, but can detect other types
+# of corruption.
+#
+reset_db
+do_test 8.1 {
+  execsql {
+    PRAGMA journal_mode = wal;
+    CREATE TABLE kv(k INTEGER PRIMARY KEY, v UNIQUE);
+    INSERT INTO kv VALUES(NULL, randomblob(750));
+    INSERT INTO kv SELECT NULL, randomblob(750) FROM kv;
+    INSERT INTO kv SELECT NULL, randomblob(750) FROM kv;
+    INSERT INTO kv SELECT NULL, randomblob(750) FROM kv;
+    INSERT INTO kv SELECT NULL, randomblob(750) FROM kv;
+    INSERT INTO kv SELECT NULL, randomblob(750) FROM kv;
+    DELETE FROM kv WHERE rowid%2;
+  }
+  set v [db one {PRAGMA freelist_count}]
+  expr $v==33 || $v==34
+} {1}
+do_execsql_test 8.2 { PRAGMA integrity_check } ok
+do_execsql_test 8.3 { 
+  BEGIN CONCURRENT;
+    PRAGMA integrity_check;
+} {ok}
+do_execsql_test 8.4 { 
+    INSERT INTO kv VALUES(1100, 1100);
+    PRAGMA integrity_check;
+} {ok}
+do_execsql_test 8.5 { 
+  COMMIT;
+  PRAGMA integrity_check;
+} {ok}
+
+#-------------------------------------------------------------------------
+# Test that concurrent transactions do not allow foreign-key constraints
+# to be bypassed.
+#
+do_multiclient_test tn {
+  do_test 9.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE pp(i INTEGER PRIMARY KEY, j);
+      CREATE TABLE cc(a, b REFERENCES pp);
+
+      WITH seq(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM seq WHERE i<100)
+      INSERT INTO pp SELECT i, randomblob(1000) FROM seq;
+
+      PRAGMA foreign_keys = 1;
+    }
+  } {wal}
+
+
+  do_test 9.$tn.2.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO cc VALUES(42, 42);
+    }
+  } {}
+  do_test 9.$tn.2.2 {
+    sql2 { DELETE FROM pp WHERE i=42 }
+    list [catch { sql1 COMMIT } msg] $msg
+  } {1 {database is locked}}
+  do_test 9.$tn.2.3 {
+    sql1 ROLLBACK
+  } {}
+
+  do_test 9.$tn.3.1 {
+    sql1 {
+      PRAGMA foreign_keys = 0;
+      BEGIN CONCURRENT;
+        INSERT INTO cc VALUES(43, 43);
+    }
+  } {}
+  do_test 9.$tn.3.2 {
+    sql2 { DELETE FROM pp WHERE i=43 }
+    list [catch { sql1 COMMIT } msg] $msg
+  } {0 {}}
+
+  do_test 9.$tn.4.1 {
+    sql1 {
+      PRAGMA foreign_keys = on;
+      BEGIN CONCURRENT;
+        INSERT INTO cc VALUES(44, 44);
+    }
+  } {}
+  do_test 9.$tn.4.2 {
+    sql2 { DELETE FROM pp WHERE i=1 }
+    list [catch { sql1 COMMIT } msg] $msg
+  } {0 {}}
+}
+
+#-------------------------------------------------------------------------
+# Test that even if a SELECT statement appears before all writes within
+# a CONCURRENT transaction, the pages it reads are still considered when
+# considering whether or not the transaction may be committed.
+#
+do_multiclient_test tn {
+  do_test 10.$tn.1.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(a);
+      CREATE TABLE t2(b);
+      CREATE TABLE t3(c);
+      INSERT INTO t1 VALUES(1), (2), (3);
+      INSERT INTO t2 VALUES(1), (2), (3);
+      INSERT INTO t3 VALUES(1), (2), (3);
+    }
+  } {wal}
+
+  do_test 10.$tn.1.2 {
+    sql1 {
+      BEGIN CONCURRENT;
+        SELECT * FROM t1;
+        INSERT INTO t2 VALUES(4);
+    }
+  } {1 2 3}
+
+  do_test 10.$tn.1.3 {
+    sql2 { INSERT INTO t1 VALUES(4) }
+    list [catch {sql1 COMMIT} msg] $msg
+  } {1 {database is locked}}
+  sql1 ROLLBACK
+
+  # In this case, because the "SELECT * FROM t1" is first stepped before
+  # the "BEGIN CONCURRENT", the pages it reads are not recorded by the
+  # pager object. And so the transaction can be committed. Technically
+  # this behaviour (the effect of an ongoing SELECT on a BEGIN CONCURRENT
+  # transacation) is undefined.
+  #
+  do_test 10.$tn.2.1 {
+    code1 {
+      set ::stmt [sqlite3_prepare db "SELECT * FROM t1" -1 dummy]
+      sqlite3_step $::stmt
+    }
+  } {SQLITE_ROW}
+  do_test 10.$tn.2.2 {
+    sql1 {
+      BEGIN CONCURRENT; 
+        INSERT INTO t2 VALUES(4);
+    }
+    code1 {
+      set res [list]
+      lappend res [sqlite3_column_int $::stmt 0]
+      while {[sqlite3_step $::stmt]=="SQLITE_ROW"} {
+        lappend res [sqlite3_column_int $::stmt 0]
+      }
+      sqlite3_finalize $::stmt
+      set res
+    }
+  } {1 2 3 4}
+  do_test 10.$tn.2.3 {
+    sql2 { INSERT INTO t1 VALUES(5) }
+    sql1 COMMIT
+  } {}
+
+  # More tests surrounding long-lived prepared statements and concurrent
+  # transactions.
+  do_test 10.$tn.3.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        SELECT * FROM t1;
+      COMMIT;
+    }
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t2 VALUES(5);
+    }
+    sql2 {
+      INSERT INTO t1 VALUES(5);
+    }
+    sql1 COMMIT
+    sql3 {
+      SELECT * FROM t2;
+    }
+  } {1 2 3 4 5}
+  do_test 10.$tn.3.2 {
+    sql1 {
+      BEGIN CONCURRENT;
+        SELECT * FROM t1;
+      ROLLBACK;
+    }
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t2 VALUES(6);
+    }
+    sql2 {
+      INSERT INTO t1 VALUES(6);
+    }
+    sql1 COMMIT
+    sql3 { SELECT * FROM t2 }
+  } {1 2 3 4 5 6}
+  do_test 10.$tn.3.3 {
+    sql1 { BEGIN CONCURRENT }
+    code1 {
+      set ::stmt [sqlite3_prepare db "SELECT * FROM t1" -1 dummy]
+      sqlite3_step $::stmt
+    }
+    sql1 {
+      INSERT INTO t2 VALUES(7);
+      SELECT * FROM t3;
+      ROLLBACK;
+      BEGIN CONCURRENT;
+    }
+    sql2 { INSERT INTO t3 VALUES(5) }
+    code1 { sqlite3_finalize $::stmt }
+    sql1 {
+      INSERT INTO t2 VALUES(8);
+      COMMIT;
+    }
+  } {}
+}
+
+do_multiclient_test tn {
+  do_test 11.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(a);
+    }
+  } {wal}
+
+  do_test 11.$tn.2 {
+    code1 { sqlite3_wal_info db main }
+  } {0 2}
+
+  do_test 11.$tn.3 {
+    sql1 { INSERT INTO t1 VALUES(1) }
+    code1 { sqlite3_wal_info db main }
+  } {2 3}
+
+  do_test 11.$tn.4 {
+    sql2 { INSERT INTO t1 VALUES(2) }
+    code2 { sqlite3_wal_info db2 main }
+  } {3 4}
+
+  do_test 11.$tn.5 {
+    sql1 { PRAGMA wal_checkpoint }
+    sql2 { INSERT INTO t1 VALUES(3) }
+    code2 { sqlite3_wal_info db2 main }
+  } {0 1}
+}
+
+reset_db
+do_execsql_test 12.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE tx(a INTEGER PRIMARY KEY, b);
+} {wal}
+do_test 12.1 {
+  for {set i 0} {$i < 50} {incr i} {
+    execsql {
+      BEGIN CONCURRENT;
+      INSERT INTO tx(b) VALUES( randomblob( 1200 ) );
+      COMMIT;
+    }
+  }
+  execsql { PRAGMA page_size }
+} {1024}
+do_execsql_test 12.2 {
+  DELETE FROM tx;
+}
+do_test 12.3 {
+  for {set i 0} {$i < 50} {incr i} {
+    execsql {
+      BEGIN CONCURRENT;
+      INSERT INTO tx(b) VALUES( randomblob( 1200 ) );
+      COMMIT;
+    }
+  }
+  execsql { PRAGMA page_size }
+} {1024}
+do_execsql_test 12.4 {
+  DELETE FROM tx;
+}
+do_test 12.5 {
+  execsql { BEGIN CONCURRENT }
+  for {set i 0} {$i < 5000} {incr i} {
+    execsql {
+      INSERT INTO tx(b) VALUES( randomblob( 1200 ) );
+    }
+  }
+  execsql { COMMIT }
+  execsql { PRAGMA page_size }
+} {1024}
+
+
+finish_test
@@ -0,0 +1,231 @@
+# 2015 July 26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# Tests for transactions started with BEGIN CONCURRENT. The tests in this
+# file focus on testing that deferred page allocation works properly.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+set ::testprefix concurrent3
+
+if {$AUTOVACUUM} { finish_test ; return }
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+db close
+sqlite3_shutdown
+test_sqlite3_log xLog
+proc xLog {error_code msg} {
+  # puts "$error_code: $msg"
+  # Enable the previous for debugging
+}
+reset_db
+
+proc create_schema {} {
+  db eval {
+    PRAGMA journal_mode = wal;
+
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(x, y);
+    CREATE TABLE t3(x, y);
+    CREATE TABLE t4(x, y);
+
+    CREATE INDEX i1 ON t1(y, x);
+    CREATE INDEX i2 ON t2(y, x);
+    CREATE INDEX i3 ON t3(y, x);
+    CREATE INDEX i4 ON t4(y, x);
+  }
+}
+
+proc do_sql_op {iTbl iOp} {
+  set db "db$iTbl"
+
+  switch $iOp {
+    "i" {
+      set sql "
+        WITH cnt(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM cnt WHERE i<10)
+        INSERT INTO t$iTbl SELECT randomblob(800), randomblob(800) FROM cnt;
+      "
+    }
+
+    "d" {
+      set sql "
+        DELETE FROM t$iTbl WHERE rowid IN (
+          SELECT rowid FROM t$iTbl ORDER BY 1 ASC LIMIT 10
+        )
+      "
+    }
+
+    "D" {
+      set sql "
+        DELETE FROM t$iTbl WHERE rowid IN (
+          SELECT rowid FROM t$iTbl o WHERE (
+            SELECT count(*) FROM t$iTbl i WHERE i.rowid<o.rowid
+          ) % 2
+        )
+      "
+    }
+
+    "I" {
+      set sql "
+        INSERT INTO t$iTbl SELECT randomblob(800), randomblob(800) FROM t$iTbl;
+      "
+    }
+
+    default {
+      error "bad iOp parameter: $iOp"
+    }
+  }
+
+  $db eval $sql
+}
+
+
+set DBLIST {db1 db2 db3 db4} 
+
+create_schema
+foreach {tn oplist} {
+  1  {1i   2i   3i   4i} 
+  2  {1iii 2iii 3iii 4iii}
+  3  {1d   2d   3d   4d} 
+  .  -----------------------
+  4  {1i}
+  5  {1d 2i}
+  .  -----------------------
+  6  {1iii 2iii 3iii 4iii}
+  7  {1di  2id  3iii 4ddd}
+  8  {1iii 2iii 3iii 4iii}
+  9  {1D  2II}
+  10 {1I  2D  3I  4D}
+  11 {1III 3dddddd 4III}
+} {
+  if {[string range $oplist 0 0]=="-"} {
+    reset_db
+    create_schema
+    continue
+  }
+  foreach db $DBLIST { sqlite3 $db test.db }
+
+  do_test 1.$tn {
+    foreach db $DBLIST { $db eval "BEGIN CONCURRENT" } 
+
+    foreach op $oplist {
+      set iTbl [string range $op 0 0]
+      foreach char [split [string range $op 1 end] {}] {
+        do_sql_op $iTbl $char
+      }
+    }
+
+    foreach db $DBLIST { $db eval "COMMIT" }
+    db eval {PRAGMA integrity_check}
+  } {ok}
+
+  foreach db $DBLIST { 
+    $db close 
+  }
+}
+
+#-------------------------------------------------------------------------
+#
+proc create_schema2 {} {
+  db eval {
+    PRAGMA journal_mode = wal;
+    CREATE TABLE t1(x INTEGER PRIMARY KEY, y);
+    CREATE INDEX i1 ON t1(y);
+  }
+}
+
+proc randint {nMax} {
+  db eval {SELECT abs(random() % $nMax)}
+}
+
+proc do_sql_op2 {db iOp} {
+  switch -- $iOp {
+    i {
+      # Insert 1 rows.
+      set r [randint 1000000000]
+      set ::rows($r) 1
+      #puts "insert row $r"
+      $db eval { INSERT OR IGNORE INTO t1 VALUES($r, randomblob(50)); }
+    }
+
+    d {
+      # Insert 1 row
+      set keys [array names ::rows]
+      set r [randint [llength $keys]]
+      set rowid [lindex $keys $r]
+      $db eval { DELETE FROM t1 WHERE x=$rowid }
+      unset ::rows($rowid)
+    }
+  }
+}
+
+foreach {tn nRepeat oplist} {
+  - - ----------------------------
+  1 100 { 1iiiiiiiiii }
+  2 100 { 1i 2d }
+  3 100 { 1d 2i }
+  4  50 { 1d 2i 3d }
+  5 500 { 1i 2i 3i 4i }
+  6 500 { 1i 2d 3d 4d }
+} {
+  if {[string range $oplist 0 0]=="-"} {
+    array unset rows
+    reset_db
+    create_schema2
+    continue
+  }
+
+  foreach db $DBLIST { 
+    sqlite3 $db test.db 
+    set stats($db,0) 0
+    set stats($db,1) 0
+  }
+  array unset used
+
+  do_test 2.$tn {
+
+    for {set i 0} {$i < $nRepeat} {incr i} {
+      foreach db $DBLIST { $db eval "BEGIN CONCURRENT" } 
+
+      foreach op $oplist {
+        set iDb [string range $op 0 0]
+        set used(db$iDb) 1
+        foreach char [split [string range $op 1 end] {}] {
+          do_sql_op2 "db$iDb" $char
+        }
+      }
+
+      foreach db $DBLIST { 
+        set rc [catch { $db eval COMMIT } msg]
+        if {$rc} { $db eval ROLLBACK }
+        incr stats($db,$rc)
+      }
+      set res [db eval {PRAGMA integrity_check}]
+      if {$res != "ok"} { puts "after $db $rc: $res" ; after 1000000 }
+    }
+  } {}
+
+  foreach db $DBLIST { 
+    $db close 
+  }
+  # foreach k [lsort [array names used]] {
+  #   puts "$k: $stats($k,0) committed, $stats($k,1) rolled back"
+  # }
+}
+
+
+
+finish_test
@@ -0,0 +1,194 @@
+# 2017 May 26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# Miscellaneous tests for transactions started with BEGIN CONCURRENT. 
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/wal_common.tcl
+set ::testprefix concurrent4
+
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x PRIMARY KEY, y UNIQUE);
+  WITH s(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100)
+  INSERT INTO t1 SELECT randomblob(400), randomblob(400) FROM s;
+  DELETE FROM t1 WHERE rowid<2;
+} {wal}
+
+do_execsql_test 1.1 {
+  BEGIN CONCURRENT;
+    INSERT INTO t1(rowid, x, y) VALUES(1000, randomblob(3000), randomblob(3000));
+    SAVEPOINT abc;
+    DELETE FROM t1 WHERE rowid = 1000;
+}
+
+do_execsql_test 1.2 { ROLLBACK TO abc }
+do_execsql_test 1.3 { COMMIT }
+do_execsql_test 1.4 { PRAGMA integrity_check } {ok}
+
+do_multiclient_test tn {
+  do_test 2.$tn.1 {
+    sql1 {
+      PRAGMA journal_mode = wal;
+      CREATE TABLE t1(a, b);
+      WITH s(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100)
+        INSERT INTO t1 SELECT randomblob(400), randomblob(400) FROM s;
+
+      CREATE TABLE t2(a, b);
+      WITH s(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100)
+        INSERT INTO t2 SELECT randomblob(400), randomblob(400) FROM s;
+    }
+
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(randomblob(3000), randomblob(3000));
+    }
+  } {}
+
+  do_test 2.$tn.2 {
+    sql2 {
+      WITH s(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<10)
+        INSERT INTO t2 SELECT randomblob(400), randomblob(400) FROM s;
+    }
+    sql2 {
+      DELETE FROM t2 WHERE rowid<10;
+    }
+  } {}
+
+  do_test 2.$tn.3 {
+    sql1 {
+      COMMIT;
+      PRAGMA integrity_check;
+    }
+  } {ok}
+  do_test 2.$tn.4 {
+    sql2 {
+      PRAGMA integrity_check;
+    }
+  } {ok}
+}
+
+reset_db
+do_execsql_test 3.1 {
+  PRAGMA page_size = 1024;
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t2(x);
+  INSERT INTO t2 VALUES(randomblob(5000));
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
+  INSERT INTO t1 VALUES(25, randomblob(104));
+  DELETE FROM t2;
+} {wal}
+
+do_execsql_test 3.2 {
+  BEGIN CONCURRENT;
+    REPLACE INTO t1 VALUES(25, randomblob(1117));
+  COMMIT;
+} {}
+
+#-------------------------------------------------------------------------
+# Test the effect of BEGIN CONCURRENT transactions that consist entirely
+# of read-only statements.
+#
+reset_db
+do_execsql_test 4.0 {
+  PRAGMA page_size = 1024;
+  PRAGMA journal_mode = wal;
+  
+  CREATE TABLE t4(a, b);
+  INSERT INTO t4 VALUES(1, 2);
+  INSERT INTO t4 VALUES(3, 4);
+} {wal}
+ 
+sqlite3 db2 test.db
+do_test 4.1.1 {
+  db eval {
+    BEGIN CONCURRENT;
+      INSERT INTO t4 VALUES(5, 6);
+  }
+
+  db2 eval {
+    BEGIN CONCURRENT;
+      SELECT * FROM t4;
+    ROLLBACK;
+  }
+} {1 2 3 4}
+
+do_test 4.1.2 {
+  db eval { COMMIT }
+  db2 eval { SELECT * FROM t4 }
+} {1 2 3 4 5 6}
+
+do_test 4.2.1 {
+  db eval {
+    BEGIN CONCURRENT;
+      INSERT INTO t4 VALUES(7, 8);
+  }
+
+  db2 eval {
+    BEGIN CONCURRENT;
+      SELECT * FROM t4;
+    COMMIT;
+  }
+} {1 2 3 4 5 6}
+
+do_test 4.2.2 {
+  db eval { COMMIT }
+  db2 eval { SELECT * FROM t4 }
+} {1 2 3 4 5 6 7 8}
+
+do_test 4.3 {
+  db2 eval {
+    BEGIN CONCURRENT;
+      SELECT * FROM t4;
+  }
+
+  db eval {
+    BEGIN CONCURRENT;
+      INSERT INTO t4 VALUES(9, 10);
+    COMMIT;
+  }
+  db2 eval {
+    SELECT * FROM t4;
+    COMMIT;
+  }
+} {1 2 3 4 5 6 7 8}
+
+set sz [file size test.db-wal]
+do_test 4.4.1 {
+  db eval {
+    BEGIN CONCURRENT;
+      SELECT * FROM t4;
+      SELECT * FROM sqlite_master;
+  }
+
+  db eval COMMIT
+  file size test.db-wal
+} $sz
+do_test 4.4.2 {
+  db eval {
+    BEGIN CONCURRENT;
+      SELECT * FROM t4;
+      SELECT * FROM sqlite_master;
+    ROLLBACK;
+  }
+  file size test.db-wal
+} $sz
+
+finish_test
+
@@ -0,0 +1,133 @@
+# 2017 May 26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/wal_common.tcl
+set ::testprefix concurrent5
+
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+db close
+sqlite3_shutdown
+test_sqlite3_log [list lappend ::log]
+set ::log [list]
+
+sqlite3 db test.db
+
+proc do_test_conflict_msg {tn msg} {
+  set msg "cannot commit CONCURRENT transaction - [string trim $msg]"
+  uplevel [list do_test $tn {lindex $::log end} $msg]
+}
+
+do_execsql_test 1.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x, y);
+  CREATE TABLE t2(c);
+  WITH s(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100)
+  INSERT INTO t1 SELECT randomblob(400), randomblob(400) FROM s;
+} {wal}
+
+sqlite3 db2 test.db
+
+do_test 1.1.1 {
+  set ::log [list]
+  db2 eval {
+    BEGIN CONCURRENT;
+      SELECT count(*) FROM t1;
+      INSERT INTO t2 VALUES(10);
+  }
+
+  db eval {
+    INSERT INTO t1 VALUES(randomblob(200), randomblob(200));
+  }
+
+  catchsql COMMIT db2
+} {1 {database is locked}}
+do_test_conflict_msg 1.1.2 {
+  conflict at page 2 (read-only page; part of db table t1; content=0500000063021100...)
+}
+
+do_test 1.2.1 {
+  set ::log [list]
+  db2 eval {
+    ROLLBACK;
+    BEGIN CONCURRENT;
+      INSERT INTO t1 VALUES(11, 12);
+  }
+
+  db eval {
+    INSERT INTO t1 VALUES(12, 11);
+  }
+
+  catchsql COMMIT db2
+} {1 {database is locked}}
+
+do_test_conflict_msg 1.2.2 {
+  conflict at page 105 (read/write page; part of db table t1; content=0D00000002026100...)
+}
+
+do_test 1.3.1 {
+  set ::log [list]
+  db2 eval {
+    ROLLBACK;
+    BEGIN CONCURRENT;
+      INSERT INTO t2 VALUES('x');
+  }
+
+  db eval {
+    INSERT INTO t2 VALUES('y');
+  }
+
+  catchsql COMMIT db2
+} {1 {database is locked}}
+
+do_test_conflict_msg 1.3.2 {
+  conflict at page 3 (read/write page; part of db table t2; content=0D0000000103FB00...)
+}
+
+do_test 1.4.1 {
+  set ::log [list]
+
+  execsql {
+    ROLLBACK;
+    CREATE TABLE t3(a INTEGER PRIMARY KEY, b INTEGER);
+    CREATE INDEX i3 ON t3(b);
+
+    WITH s(i) AS (
+      SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<5000
+    ) INSERT INTO t3 SELECT i, i FROM s;
+
+    BEGIN CONCURRENT;
+      INSERT INTO t3 VALUES(0, 5001);
+  } db2
+
+  execsql { INSERT INTO t3 VALUES(NULL, 5002) } db
+  catchsql COMMIT db2
+} {1 {database is locked}}
+
+do_test_conflict_msg 1.3.2 {
+  conflict at page 211 (read/write page; part of db index t3.i3; content=0A0310006300D800...)
+}
+
+db close
+db2 close
+sqlite3_shutdown
+test_sqlite3_log 
+sqlite3_initialize
+finish_test
+
@@ -0,0 +1,60 @@
+# 2017 May 26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/wal_common.tcl
+set ::testprefix concurrent6
+
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+sqlite3 db2 test.db
+
+do_execsql_test 1.0 {
+  PRAGMA page_size = 1024;
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x);
+  CREATE TABLE t2(x);
+  CREATE TABLE t3(x);
+  CREATE TABLE t4(x);
+
+  INSERT INTO t1 VALUES(zeroblob(1500));
+} {wal}
+
+do_execsql_test -db db2 1.1 {
+  BEGIN CONCURRENT;
+    INSERT INTO t3 VALUES(zeroblob(4000));
+    DELETE FROM t1;
+}
+
+do_execsql_test 1.2 {
+  WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100) 
+  INSERT INTO t2 SELECT zeroblob(1000) FROM s;
+
+  WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100) 
+  INSERT INTO t4  SELECT zeroblob(1000) FROM s;
+
+  DELETE FROM t4;
+}
+
+do_execsql_test -db db2 1.3 {
+  COMMIT;
+}
+
+
+finish_test
+
@@ -0,0 +1,52 @@
+# 2018 Jan 5
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set ::testprefix concurrent7
+
+sqlite3 db2 test.db
+
+do_execsql_test 1 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE t1(x);
+  CREATE TABLE t2(x);
+} {wal}
+
+do_execsql_test -db db2 2 {
+  SELECT * FROM t1;
+}
+
+do_execsql_test 3 {
+  BEGIN CONCURRENT;
+    INSERT INTO t1 VALUES(randomblob(1500));
+    INSERT INTO t1 VALUES(randomblob(1500));
+    DELETE FROM t1 WHERE rowid = 1;
+}
+
+do_execsql_test -db db2 4 {
+  INSERT INTO t2 VALUES(randomblob(1500));
+  INSERT INTO t2 VALUES(randomblob(1500));
+  INSERT INTO t2 VALUES(randomblob(1500));
+  INSERT INTO t2 VALUES(randomblob(1500));
+  DELETE FROM t2 WHERE rowid IN (1, 2);
+}
+
+do_execsql_test 5 {
+  COMMIT;
+  PRAGMA integrity_check;
+} {ok}
+
+finish_test
+
+
@@ -0,0 +1,109 @@
+# 2020 July 17
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set ::testprefix concurrent8
+
+source $testdir/lock_common.tcl
+
+ifcapable !concurrent {
+  finish_test
+  return
+}
+
+do_multiclient_test tn {
+
+  do_test 1.$tn.0 {
+    sql1 {
+      CREATE TABLE t1(x, y);
+      PRAGMA journal_mode = wal;
+    }
+  } {wal}
+
+  do_test 1.$tn.1 {
+    sql1 {
+      BEGIN CONCURRENT;
+        INSERT INTO t1 VALUES(1, 1);
+    }
+  } {}
+
+  do_test 1.$tn.2 {
+    sql2 {
+      CREATE TABLE t2(a, b);
+    }
+  } {}
+
+  do_test 1.$tn.3 {
+    list [catch { sql1 { COMMIT } } msg] $msg
+  } {1 {database is locked}}
+
+  do_test 1.$tn.4 {
+    code1 { db errorcode }
+  } {517}  ;# SQLITE_BUSY_SNAPSHOT
+
+  do_test 1.$tn.5 {
+    sql1 {
+      ROLLBACK;
+      BEGIN CONCURRENT;
+        CREATE TABLE t3(a, b);
+      COMMIT;
+    }
+  } {}
+
+  do_test 1.$tn.6 {
+    set nPg [sql1 {PRAGMA page_count}]
+    sql1 "BEGIN CONCURRENT"
+    for {set i 0} {$i<250} {incr i} {
+      sql1 "CREATE TABLE z$i (a, b, c)"
+    }
+    sql1 "COMMIT"
+    set nPg2 [sql1 {PRAGMA page_count}]
+    expr $nPg2>$nPg
+  } {1}
+
+  do_test 1.$tn.7 {
+    sql2 { PRAGMA integrity_check }
+  } {ok}
+
+  do_test 1.$tn.8 {
+    sql1 {
+      BEGIN CONCURRENT;
+        CREATE TABLE t4(a, b);
+    }
+    sql2 {
+      INSERT INTO t1 VALUES(2, 2);
+    }
+    list [catch { sql1 COMMIT } msg] $msg
+  } {1 {database is locked}}
+  sql1 ROLLBACK
+
+  do_test 1.$tn.9 {
+    sql1 {
+      BEGIN CONCURRENT;
+        CREATE TEMP TABLE t5(a, b);
+        INSERT INTO t2 VALUES('x', 'x');
+    }
+    sql2 {
+      INSERT INTO t1 VALUES(3, 3);
+      CREATE TEMP TABLE t1(x, y);
+    }
+    sql1 COMMIT 
+  } {}
+}
+
+
+
+finish_test
+
+
@@ -146,7 +146,7 @@ do_catchsql_test 2.1 {
 SELECT count(*) FROM sqlite_schema;
 WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<1000)
 INSERT INTO t1(a) SELECT randomblob(null) FROM c;
-} {1 {database disk image is malformed}}
+} {0 4}

 reset_db
 if {![info exists ::G(perm:presql)]} {
@@ -7033,6 +7033,8 @@ set sqlite_fts3_enable_parentheses $saved

 #-------------------------------------------------------------------------
 #
+set saved $sqlite_fts3_enable_parentheses
+set sqlite_fts3_enable_parentheses 1
 reset_db
 do_test 52.0 {
  sqlite3 db {}
@@ -7228,5 +7230,438 @@ do_catchsql_test 52.1 {
  SELECT * FROM t1, t2;
 } {1 {database disk image is malformed}}

+#-------------------------------------------------------------------------
+#
+reset_db
+do_test 53.0 {
+  sqlite3 db {}
+  db deserialize [decode_hexdb {
+.open --hexdb
+| size 8192 pagesize 1024 filename crash-7bc.txt.db
+| page 1 offset 0
+|      0: 53 51 4c 69 74 65 20 66 6f 72 6d 61 74 20 33 00   SQLite format 3.
+|     16: 04 00 01 01 00 40 20 20 00 00 00 00 00 00 00 08   .....@  ........
+|     32: 00 00 00 00 00 00 00 00 00 00 00 06 00 00 00 04   ................
+|     48: 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00   ................
+|     96: 00 00 00 00 0d 02 f3 00 07 01 51 00 03 c8 03 63   ..........Q....c
+|    112: 02 fb 02 0a 02 c0 01 a8 01 51 00 00 00 00 00 00   .........Q......
+|    336: 00 55 07 07 17 1b 1b 01 81 01 74 61 62 6c 65 74   .U........tablet
+|    352: 31 5f 73 74 61 74 74 31 5f 73 74 61 74 07 43 52   1_statt1_stat.CR
+|    368: 45 41 54 45 20 54 41 42 4c 45 20 27 74 31 5f 73   EATE TABLE 't1_s
+|    384: 74 61 74 27 28 69 64 20 49 4e 54 45 47 45 52 20   tat'(id INTEGER 
+|    400: 50 52 49 4d 41 52 59 20 4b 45 59 2c 20 76 61 6c   PRIMARY KEY, val
+|    416: 75 65 20 42 4c 4f 42 29 60 06 07 17 21 21 01 81   ue BLOB)`...!!..
+|    432: 0b 74 61 62 6c 65 74 31 5f 64 6f 63 73 69 7a 65   .tablet1_docsize
+|    448: 74 31 5f 64 6f 63 73 69 7a 65 06 43 52 45 41 54   t1_docsize.CREAT
+|    464: 45 20 54 41 42 4c 45 20 27 74 31 5f 64 6f 63 73   E TABLE 't1_docs
+|    480: 69 7a 65 27 28 64 6f 63 69 64 20 49 4e 54 45 47   ize'(docid INTEG
+|    496: 45 52 20 50 52 49 4d 41 52 59 20 4b 45 59 2c 20   ER PRIMARY KEY, 
+|    512: 73 69 7a 65 20 42 4c 4f 42 29 81 33 04 07 17 1f   size BLOB).3....
+|    528: 1f 01 82 35 74 61 62 6c 65 74 31 5f 73 65 67 64   ...5tablet1_segd
+|    544: 69 72 74 31 5f 73 65 67 64 69 72 04 43 52 45 41   irt1_segdir.CREA
+|    560: 54 45 20 54 41 42 4c 45 20 27 74 31 5f 73 65 67   TE TABLE 't1_seg
+|    576: 64 69 72 27 28 6c 65 76 65 6c 20 49 4e 54 45 47   dir'(level INTEG
+|    592: 45 52 2c 69 64 78 20 49 4e 54 45 47 45 52 2c 73   ER,idx INTEGER,s
+|    608: 74 61 72 74 5f 62 6c 6f 63 6b 20 49 4e 54 45 47   tart_block INTEG
+|    624: 45 52 2c 6c 65 61 76 65 73 5f 65 6e 64 5f 62 6c   ER,leaves_end_bl
+|    640: 6f 63 6b 20 49 4e 54 45 47 45 52 2c 65 6e 64 5f   ock INTEGER,end_
+|    656: 62 6c 6f 63 6b 20 49 4e 54 45 47 45 52 2c 72 6f   block INTEGER,ro
+|    672: 6f 74 20 42 4c 4f 42 2c 50 52 49 4d 41 52 59 20   ot BLOB,PRIMARY 
+|    688: 4b 45 59 28 6c 65 76 65 6c 2c 20 69 64 78 29 29   KEY(level, idx))
+|    704: 31 05 06 17 45 1f 01 00 69 6e 64 65 78 73 71 6c   1...E...indexsql
+|    720: 69 74 65 5f 61 75 74 6f 69 6e 64 65 78 5f 74 31   ite_autoindex_t1
+|    736: 5f 73 65 67 64 69 72 5f 31 74 31 5f 73 65 67 64   _segdir_1t1_segd
+|    752: 69 72 05 00 00 00 08 00 00 00 00 66 03 07 17 23   ir.........f...#
+|    768: 23 01 81 13 74 61 62 6c 65 74 31 5f 73 65 67 6d   #...tablet1_segm
+|    784: 65 6e 74 73 74 31 5f 73 65 67 6d 65 6e 74 73 03   entst1_segments.
+|    800: 43 52 45 41 54 45 20 54 41 42 4c 45 20 27 74 31   CREATE TABLE 't1
+|    816: 5f 73 65 67 6d 65 6e 74 73 27 28 62 6c 6f 63 6b   _segments'(block
+|    832: 69 64 20 49 4e 53 45 47 45 52 20 50 52 49 4d 41   id INSEGER PRIMA
+|    848: 52 59 20 4b 45 59 2c 20 62 6c 6f 63 6b 20 42 4c   RY KEY, block BL
+|    864: 4f 42 29 63 02 07 17 21 21 01 81 11 74 61 62 6c   OB)c...!!...tabl
+|    880: 65 74 31 5f 63 6f 6e 74 65 6e 74 74 31 5f 63 6f   et1_contentt1_co
+|    896: 6e 74 65 6e 74 02 43 52 45 41 54 45 20 54 41 42   ntent.CREATE TAB
+|    912: 4c 45 20 27 74 31 5f 63 6f 6e 74 65 6e 74 27 28   LE 't1_content'(
+|    928: 64 6f 63 69 64 20 49 4e 54 45 47 45 52 20 50 52   docid INTEGER PR
+|    944: 49 4d 41 52 59 20 4b 45 59 2c 20 27 63 30 30 27   IMARY KEY, 'c00'
+|    960: 2c 20 27 63 31 62 27 29 36 01 06 17 11 11 08 5b   , 'c1b')6......[
+|    976: 74 61 62 6c 65 74 31 74 31 43 52 45 41 54 45 20   tablet1t1CREATE 
+|    992: 56 49 52 54 55 41 4c 20 54 41 42 4c 45 20 74 31   VIRTUAL TABLE t1
+|   1008: 20 55 53 49 4e 47 20 66 74 73 34 28 30 2c 62 29    USING fts4(0,b)
+| page 2 offset 1024
+|      0: 0d 00 00 00 03 00 0f 00 00 23 00 16 00 0f 00 05   .........#......
+|     16: 03 04 00 08 0f 61 0b 02 04 00 08 1b 41 54 45 20   .....a......ATE 
+|     32: 32 3a 50 87 5a 01 05 00 08 8f 37 66 30 30 30 30   2:P.Z.....7f0000
+|     48: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     64: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     80: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     96: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    112: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    128: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    144: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    160: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    176: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    192: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    208: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    224: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    240: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    256: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    272: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    288: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    304: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
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+|    336: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    352: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    368: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    384: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
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+|    416: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    432: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    448: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    464: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    480: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    496: 30 40 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0@00000000000000
+|    512: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    528: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    544: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    560: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    576: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    592: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    608: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    624: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    640: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    656: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    672: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    688: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    704: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    720: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    736: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    752: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    768: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    784: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    800: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    816: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    832: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    848: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    864: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    880: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    896: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    912: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    928: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    944: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    960: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    976: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    992: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|   1008: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+| page 3 offset 2048
+|      0: 0d 00 00 00 02 03 86 00 03 f4 03 86 00 00 00 00   ................
+|    896: 00 00 00 00 00 00 87 62 02 04 00 8f 48 00 d5 07   .......b....H...
+|    912: 66 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   f000000000000000
+|    928: 30 30 30 30 3a 30 30 30 30 30 30 30 30 30 30 30   0000:00000000000
+|    944: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    960: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    976: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    992: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|   1008: 00 00 00 08 0a 01 03 00 1a 00 01 30 03 01 02 00   ...........0....
+| page 4 offset 3072
+|      0: 0d 00 00 00 03 03 9e 00 03 ed 03 bc 03 9e 00 00   ................
+|    912: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1c 03   ................
+|    928: 07 08 01 08 08 15 2c 02 30 20 31 36 00 01 30 03   ......,.0 16..0.
+|    944: 03 02 00 00 01 61 05 03 01 01 02 00 2f 02 07 08   .....a....../...
+|    960: 09 08 08 15 54 30 20 33 36 00 01 30 03 02 02 00   ....T0 36..0....
+|    976: 00 01 32 05 02 01 01 03 00 00 03 61 74 65 05 02   ..2........ate..
+|    992: 01 01 02 00 00 01 70 05 02 01 01 04 00 11 01 07   ......p.........
+|   1008: 08 08 09 01 17 14 02 32 20 39 39 37 01 01 01 66   .......2 997...f
+| page 5 offset 4096
+|      0: 0a 00 00 00 03 03 ee 00 03 fb 03 f5 03 ee 00 00   ................
+|    992: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 06 04   ................
+|   1008: 08 01 01 02 03 05 04 08 09 01 02 04 04 08 08 09   ................
+| page 6 offset 5120
+|      0: 0d 00 00 00 03 03 eb 00 00 00 00 00 00 00 00 00   ................
+|    992: 00 00 00 00 00 00 00 00 00 00 00 05 03 03 00 10   ................
+|   1008: 01 01 05 02 03 00 10 01 03 05 01 03 00 10 01 01   ................
+| page 7 offset 6144
+|      0: 0d 00 00 00 01 03 f6 00 03 f6 00 00 00 00 00 00   ................
+|   1008: 00 00 00 00 00 00 08 00 03 00 16 03 08 c5 e0 07   ................
+| page 8 offset 7168
+|      0: 00 00 00 00 30 30 30 30 30 30 30 30 30 30 30 30   ....000000000000
+|     16: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     32: 30 30 30 30 30 30 30 30 30 30 30 30 30 bc 30 30   0000000000000.00
+|     48: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     64: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     80: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     96: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    112: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    128: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    144: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    160: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    176: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    192: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 c0 30   00000000000000.0
+|    208: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    224: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    240: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    256: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    272: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    288: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    304: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    320: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    336: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    352: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    368: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    384: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    400: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    416: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
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+|    480: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    496: 30 30 30 30 30 30 30 30 30 30 30 40 30 30 30 30   00000000000@0000
+|    512: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    528: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
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+|    576: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    592: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    608: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    624: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    640: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
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+|    672: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    688: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    704: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    720: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    736: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    752: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    768: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    784: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    800: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    816: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    832: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    848: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    864: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    880: 30 30 30 30 30 30 30 30 30 05 01 00 00 00 00 00   000000000.......
+| end crash-7bc.txt.db
+}]} {}
+
+do_execsql_test 53.1 {
+  SELECT*FROM t1 WHERE t1 MATCH'ATE"0"OR"2D:P"""ATE"0"OR"2:P"""';
+} {0 {ATE 2:P}}
+set sqlite_fts3_enable_parentheses $saved
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_test 54.0 {
+  sqlite3 db {}
+  db deserialize [decode_hexdb {
+.open --hexdb
+| size 8192 pagesize 1024 filename crash-365.txt.db
+| page 1 offset 0
+|      0: 53 51 4c 69 74 65 20 66 6f 72 6d 61 74 20 33 00   SQLite format 3.
+|     16: 04 00 01 01 00 40 20 20 00 00 00 00 00 00 00 08   .....@  ........
+|     32: 00 00 00 00 00 00 00 00 00 00 00 06 00 00 00 04   ................
+|     96: 00 00 00 00 0d 02 f3 00 07 01 51 00 03 c8 03 63   ..........Q....c
+|    112: 02 fb 02 0a 02 c0 01 a8 01 51 00 00 00 00 00 00   .........Q......
+|    336: 00 55 07 07 17 1b 1b 01 81 01 74 61 62 6c 65 74   .U........tablet
+|    352: 31 5f 73 74 61 74 74 31 5f 73 74 61 74 07 43 52   1_statt1_stat.CR
+|    368: 45 41 54 45 20 54 41 42 4c 45 20 27 74 31 5f 73   EATE TABLE 't1_s
+|    384: 74 61 74 27 28 69 64 20 49 4e 54 45 47 45 52 20   tat'(id INTEGER 
+|    400: 50 52 49 4d 41 52 59 20 4b 45 59 2c 20 76 61 6c   PRIMARY KEY, val
+|    416: 75 65 20 42 4c 4f 42 29 60 06 07 17 21 21 01 81   ue BLOB)`...!!..
+|    432: 0b 74 61 62 6c 65 74 31 5f 64 6f 63 73 69 7a 65   .tablet1_docsize
+|    448: 74 31 5f 64 6f 63 73 69 7a 65 06 43 52 45 41 54   t1_docsize.CREAT
+|    464: 45 20 54 41 42 4c 45 20 27 74 31 5f 64 6f 63 73   E TABLE 't1_docs
+|    480: 69 7a 65 27 28 64 6f 63 69 64 20 49 4e 54 45 47   ize'(docid INTEG
+|    496: 45 52 20 50 52 49 4d 41 52 59 20 4b 45 59 2c 20   ER PRIMARY KEY, 
+|    512: 73 69 7a 65 20 42 4c 4f 42 29 81 33 04 07 17 1f   size BLOB).3....
+|    528: 1f 01 82 35 74 61 62 6c 65 74 31 5f 73 65 67 64   ...5tablet1_segd
+|    544: 69 72 74 31 5f 73 65 67 64 69 72 04 43 52 45 41   irt1_segdir.CREA
+|    560: 54 45 20 54 41 42 4c 45 20 27 74 31 5f 73 65 67   TE TABLE 't1_seg
+|    576: 64 69 72 27 28 6c 65 76 65 6c 20 49 4e 54 45 47   dir'(level INTEG
+|    592: 45 52 2c 69 64 78 20 49 4e 54 45 47 45 52 2c 73   ER,idx INTEGER,s
+|    608: 74 61 72 74 5f 62 6c 6f 63 6b 20 49 4e 54 45 47   tart_block INTEG
+|    624: 45 52 2c 6c 65 61 76 65 73 5f 65 6e 64 5f 62 6c   ER,leaves_end_bl
+|    640: 6f 63 6b 20 49 4e 54 45 47 45 52 2c 65 6e 64 5f   ock INTEGER,end_
+|    656: 62 6c 6f 63 6b 20 49 4e 54 45 47 45 52 2c 72 6f   block INTEGER,ro
+|    672: 6f 74 20 42 4c 4f 42 2c 50 52 49 4d 41 52 59 20   ot BLOB,PRIMARY 
+|    688: 4b 45 59 28 6c 65 76 65 6c 2c 20 69 64 78 29 29   KEY(level, idx))
+|    704: 31 05 06 17 45 1f 01 00 69 6e 64 65 78 73 71 6c   1...E...indexsql
+|    720: 69 74 65 5f 61 75 74 6f 69 6e 64 65 78 5f 74 31   ite_autoindex_t1
+|    736: 5f 73 65 67 64 69 72 5f 31 74 31 5f 73 65 67 64   _segdir_1t1_segd
+|    752: 69 72 05 00 00 00 08 00 00 00 00 66 03 07 17 23   ir.........f...#
+|    768: 23 01 81 13 74 61 62 6c 65 74 31 5f 73 65 67 6d   #...tablet1_segm
+|    784: 65 6e 74 73 74 31 5f 73 65 67 6d 65 6e 74 73 03   entst1_segments.
+|    800: 43 52 45 41 54 45 20 54 41 42 4c 45 20 27 74 31   CREATE TABLE 't1
+|    816: 5f 73 65 67 6d 65 6e 74 73 27 28 62 6c 6f 63 6b   _segments'(block
+|    832: 69 64 20 49 4e 54 45 47 45 52 20 50 52 49 4d 41   id INTEGER PRIMA
+|    848: 52 59 20 4b 45 59 2c 20 62 6c 6f 63 6b 20 42 4c   RY KEY, block BL
+|    864: 4f 42 29 63 02 07 17 21 21 01 81 11 74 61 62 6c   OB)c...!!...tabl
+|    880: 65 74 31 5f 63 6f 6e 74 65 6e 74 74 31 5f 63 6f   et1_contentt1_co
+|    896: 6e 74 65 6e 74 02 43 52 45 41 54 45 20 54 41 42   ntent.CREATE TAB
+|    912: 4c 45 20 27 74 31 5f 63 6f 6e 74 65 6e 74 27 28   LE 't1_content'(
+|    928: 64 6f 63 69 64 20 49 4e 54 45 47 45 52 20 50 52   docid INTEGER PR
+|    944: 49 4d 41 52 59 20 4b 45 59 2c 20 27 63 30 30 27   IMARY KEY, 'c00'
+|    960: 2c 20 27 63 31 62 27 29 36 01 06 17 11 11 08 5b   , 'c1b')6......[
+|    976: 74 61 62 6c 65 74 31 74 31 43 52 45 41 54 45 20   tablet1t1CREATE 
+|    992: 56 49 52 54 55 41 4c 20 54 41 42 4c 45 20 74 31   VIRTUAL TABLE t1
+|   1008: 20 55 53 49 4e 47 20 66 74 73 34 28 30 2c 62 29    USING fts4(0,b)
+| page 2 offset 1024
+|      0: 0d 00 00 00 03 00 0f 00 00 23 00 16 00 0f 00 05   .........#......
+|     16: 03 04 00 08 0f 61 0b 02 04 00 08 1b 41 54 45 20   .....a......ATE 
+|     32: 32 3a 50 87 5a 01 05 00 08 8f 37 66 30 30 30 30   2:P.Z.....7f0000
+|     48: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     64: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     80: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     96: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    112: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    128: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    144: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    160: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    176: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    192: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    208: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    224: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    240: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    256: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    272: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    288: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    304: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    320: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    336: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    352: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    368: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    384: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    400: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    416: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    432: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    448: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    464: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    480: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    496: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    512: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    528: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    544: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    560: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    576: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    592: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    608: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    624: 30 30 30 30 30 30 30 30 30 30 1b 30 30 30 30 30   0000000000.00000
+|    640: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    656: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    672: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    688: 30 30 30 30 30 30 30 30 2f 30 30 30 30 30 30 30   00000000/0000000
+|    704: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    720: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    736: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    752: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    768: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    784: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    800: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    816: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    832: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    848: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    864: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    880: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    896: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    912: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    928: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    944: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    960: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    976: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    992: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|   1008: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+| page 3 offset 2048
+|      0: 0d 00 00 00 02 03 86 00 03 f4 03 86 00 00 00 00   ................
+|    896: 00 00 00 00 00 00 87 62 02 04 00 8f 48 00 d5 07   .......b....H...
+|    912: 66 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   f000000000000000
+|    928: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    944: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    960: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    976: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    992: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|   1008: 00 00 00 08 0a 01 03 00 1a 00 01 30 03 01 02 00   ...........0....
+| page 4 offset 3072
+|      0: 0d 00 00 00 03 03 9e 00 03 ed 03 bc 03 9e 00 01   ................
+|    912: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1c 03   ................
+|    928: 07 08 01 08 08 15 2c 02 30 20 31 36 00 01 30 03   ......,.0 16..0.
+|    944: 03 02 00 00 01 61 05 03 01 01 02 00 2f 02 07 08   .....a....../...
+|    960: 09 08 08 15 54 30 20 33 36 00 01 30 03 02 02 00   ....T0 36..0....
+|    976: 00 01 32 05 02 01 01 03 00 00 03 61 74 65 05 02   ..2........ate..
+|    992: 01 01 02 00 00 01 70 05 02 01 01 04 00 11 01 07   ......p.........
+|   1008: 08 08 09 01 17 14 02 32 20 39 39 37 01 01 01 66   .......2 997...f
+| page 5 offset 4096
+|      0: 0a 00 00 00 03 03 ee 00 03 fb 03 f5 03 ee 00 00   ................
+|    992: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 06 04   ................
+|   1008: 08 01 01 02 03 05 04 08 09 01 02 04 04 08 08 09   ................
+| page 6 offset 5120
+|      0: 0d 00 00 00 03 03 eb 00 03 f9 03 f2 00 00 00 00   ................
+|    992: 00 00 00 00 00 00 00 00 00 00 00 05 03 03 00 10   ................
+|   1008: 01 01 05 02 03 00 10 01 03 05 01 03 00 10 01 01   ................
+| page 7 offset 6144
+|      0: 0d 00 00 00 01 03 f6 00 03 f6 00 00 00 00 00 00   ................
+|   1008: 00 00 00 00 00 00 08 00 03 00 16 03 03 05 e0 07   ................
+| page 8 offset 7168
+|      0: 00 00 00 00 30 30 30 30 30 30 30 30 30 30 30 30   ....000000000000
+|     16: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     32: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     48: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     64: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     80: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|     96: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    112: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    128: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    144: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    160: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    176: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    192: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    208: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    224: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    240: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    256: 30 30 30 30 30 2f 30 30 30 30 30 30 30 30 30 30   00000/0000000000
+|    272: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    288: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    304: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    320: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    336: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    352: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    368: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    384: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    400: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    416: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    432: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    448: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    464: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    480: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    496: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    512: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    528: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    544: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    560: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    576: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    592: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    608: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    624: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    640: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    656: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    672: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    688: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    704: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    720: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    736: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    752: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    768: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    784: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    800: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    816: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    832: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    848: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    864: 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30   0000000000000000
+|    880: 30 30 30 30 30 30 30 30 30 05 01 01 01 02 00 00   000000000.......
+| end crash-365.txt.db
+}]} {}
+
+do_execsql_test 54.1 {
+  SELECT rowid, quote(matchinfo(t1,'pcxybspcxybs')) FROM t1 WHERE t1 MATCH'ATE"0"OR"2:P"""';
+}

 finish_test
@@ -18,6 +18,10 @@ set ::testprefix fts3fault
 # If SQLITE_ENABLE_FTS3 is not defined, omit this file.
 ifcapable !fts3 { finish_test ; return }

+set ::TMPDBERROR [list 1 \
+  {unable to open a temporary database file for storing temporary tables}
+]
+
 # Test error handling in the sqlite3Fts3Init() function. This is the 
 # function that registers the FTS3 module and various support functions
 # with SQLite.
@@ -49,7 +53,7 @@ do_faultsim_test 2 -prep {
 } -body {
  execsql { ALTER TABLE t1 RENAME TO t2 }
 } -test {
-  faultsim_test_result {0 {}} 
+  faultsim_test_result {0 {}} $::TMPDBERROR
 }

 # Test error handling in the special case where a single prefix query 
@@ -194,7 +198,7 @@ do_faultsim_test 8.2 -faults oom-t* -prep {
 } -body {
  execsql { SELECT mit(matchinfo(t8, 's')) FROM t8 WHERE t8 MATCH 'a b c' }
 } -test {
-  faultsim_test_result {0 3}
+  faultsim_test_result {0 3} $::TMPDBERROR
 }
 do_faultsim_test 8.3 -prep { 
  faultsim_restore_and_reopen
@@ -215,12 +215,15 @@ do_faultsim_test 8.1 -faults oom* -prep {
  faultsim_test_result {0 {}}
 }

+set ::TMPDBERROR [list 1 \
+  {unable to open a temporary database file for storing temporary tables}
+]
 do_faultsim_test 8.2 -faults oom* -prep {
  faultsim_restore_and_reopen
 } -body {
  execsql { ALTER TABLE t8 RENAME TO t8ii }
 } -test {
-  faultsim_test_result {0 {}}
+  faultsim_test_result {0 {}} $::TMPDBERROR
 }

 #-------------------------------------------------------------------------
@@ -786,4 +786,19 @@ do_execsql_test join8-25020 {
  SELECT 1 FROM t1 LEFT JOIN t2 ON true JOIN t3 ON (b2 IN (a1)) FULL JOIN t4 ON true;
 } {1}

+# 2022-07-13
+# forum/forumpost/174afeae57
+#
+reset_db
+db null -
+do_execsql_test join8-26000 {
+  CREATE TABLE t1(a INT);
+  CREATE TABLE t2(b INT, c INT);
+  CREATE VIEW t3(d) AS SELECT NULL FROM t2 FULL OUTER JOIN t1 ON c=a UNION ALL SELECT b FROM t2;
+  INSERT INTO t1(a) VALUES (NULL);
+  INSERT INTO t2(b, c) VALUES (99, NULL);
+  SELECT DISTINCT b, c, d FROM t2, t3 WHERE b<>0
+   UNION SELECT DISTINCT b, c, d FROM t2, t3 WHERE b ISNULL;
+} {99 - - 99 - 99}
+
 finish_test
@@ -867,4 +867,22 @@ do_catchsql_test json-18.5 {
  SELECT json_extract('{"":8}', '$.');
 } {1 {JSON path error near ''}}

+# 2022-08-29 https://sqlite.org/forum/forumpost/9b9e4716c0d7bbd1
+# This is not a problem specifically with JSON functions.  It is
+# a problem with transaction control.  But the json() function makes
+# the problem more easily accessible, so it is tested here.
+#
+do_execsql_test json-19.1 {
+  DROP TABLE IF EXISTS t1;
+  CREATE TABLE t1(x);
+} {}
+do_catchsql_test json-19.2 {
+  BEGIN;
+  INSERT INTO t1 VALUES(0), (json('not-valid-json'));
+} {1 {malformed JSON}}
+do_execsql_test json-19.3 {
+  COMMIT;
+  SELECT * FROM t1;
+} {}
+
 finish_test
@@ -664,6 +664,7 @@ proc do_write_test {name tbl sql} {

  if {$::DO_MALLOC_TEST } {
    set answers [list {1 {out of memory}} {0 {}}]
+    lappend answers [list 1 {unable to open a temporary database file for storing temporary tables}]
    if {$::DO_MALLOC_TEST==1} {
      set modes {100000 persistent}
    } else {
@@ -141,3 +141,5 @@ do_eqp_test 111 {
     `--RIGHT
        `--SCAN generate_series VIRTUAL TABLE INDEX 23:
 }
+
+finish_test
@@ -0,0 +1,36 @@
+# 2020 September 01
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix noop_update
+
+if {[db eval {PRAGMA noop_update}]==""} {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x, y);
+  INSERT INTO t1 VALUES('a', 111);
+}
+do_execsql_test 1.1 {
+  UPDATE t1 SET y=222 WHERE x='a';
+  SELECT * FROM t1;
+} {a 222}
+do_execsql_test 1.2 {
+  PRAGMA noop_update = 1;
+  UPDATE t1 SET y=333 WHERE x='a';
+  SELECT * FROM t1;
+} {a 222}
+
+finish_test
@@ -156,6 +156,47 @@ do_execsql_test offset1-1.4.9 {
  LIMIT 9 OFFSET 1;
 } {2 b 3 c 4 d 5 e 6 w 7 x 8 y 9 z}

-
+# 2022-08-04
+# https://sqlite.org/forum/forumpost/6b5e9188f0657616
+#
+do_execsql_test offset1-2.0 {
+  CREATE TABLE employees (
+    id integer primary key,
+    name text,
+    city text,
+    department text,
+    salary integer
+  );
+  INSERT INTO employees VALUES
+    (11,'Diane','London','hr',70),
+    (12,'Bob','London','hr',78),
+    (21,'Emma','London','it',84),
+    (22,'Grace','Berlin','it',90),
+    (23,'Henry','London','it',104),
+    (24,'Irene','Berlin','it',104),
+    (25,'Frank','Berlin','it',120),
+    (31,'Cindy','Berlin','sales',96),
+    (32,'Dave','London','sales',96),
+    (33,'Alice','Berlin','sales',100);
+  CREATE VIEW v AS
+    SELECT * FROM (
+      SELECT * FROM employees 
+       WHERE salary < 100
+       ORDER BY salary desc)
+     UNION ALL 
+     SELECT * FROM (
+       SELECT * FROM employees
+       WHERE salary >= 100
+       ORDER BY salary asc);
+} {}
+do_execsql_test offset1-2.1 {
+  SELECT * FROM v LIMIT 5 OFFSET 2;
+} {
+  22  Grace  Berlin  it      90
+  21  Emma   London  it      84
+  12  Bob    London  hr      78
+  11  Diane  London  hr      70
+  33  Alice  Berlin  sales   100
+}

 finish_test
@@ -1,103 +0,0 @@
-# 2014-08-24
-#
-# The author disclaims copyright to this source code.  In place of
-# a legal notice, here is a blessing:
-#
-#    May you do good and not evil.
-#    May you find forgiveness for yourself and forgive others.
-#    May you share freely, never taking more than you give.
-#
-#***********************************************************************
-# This file implements regression tests for SQLite library.
-# The focus of this script is testing details of the SQL language parser.
-# 
-
-set testdir [file dirname $argv0]
-source $testdir/tester.tcl
-
-do_catchsql_test parser1-1.1 {
-  CREATE TABLE t1(
-    a TEXT PRIMARY KEY,
-    b TEXT,
-    FOREIGN KEY(b COLLATE nocase DESC) REFERENCES t1(a COLLATE binary ASC)
-  );
-} {1 {syntax error after column name "b"}}
-
-
-# Verify that a legacy schema in the sqlite_master file is allowed to have
-# COLLATE, ASC, and DESC keywords on the id list of a FK constraint, and that
-# those keywords are silently ignored.
-#
-sqlite3_db_config db DEFENSIVE 0
-do_execsql_test parser1-1.2 {
-  CREATE TABLE t1(
-    a TEXT PRIMARY KEY,
-    b TEXT,
-    FOREIGN KEY(b) REFERENCES t1(a)
-  );
-  INSERT INTO t1 VALUES('abc',NULL),('xyz','abc');
-  PRAGMA writable_schema=on;
-  UPDATE sqlite_master SET sql='CREATE TABLE t1(
-    a TEXT PRIMARY KEY,
-    b TEXT,
-    FOREIGN KEY(b COLLATE nocase) REFERENCES t1(a)
-  )' WHERE name='t1';
-  SELECT name FROM sqlite_master WHERE sql LIKE '%collate%';
-} {t1}
-sqlite3 db2 test.db
-do_test parser1-1.3 {
-  sqlite3 db2 test.db
-  db2 eval {SELECT * FROM t1 ORDER BY 1}
-} {abc {} xyz abc}
-db2 close
-
-do_execsql_test parser1-1.4 {
-  UPDATE sqlite_master SET sql='CREATE TABLE t1(
-    a TEXT PRIMARY KEY,
-    b TEXT,
-    FOREIGN KEY(b ASC) REFERENCES t1(a)
-  )' WHERE name='t1';
-  SELECT name FROM sqlite_master WHERE sql LIKE '%ASC%';
-} {t1}
-sqlite3 db2 test.db
-do_test parser1-1.5 {
-  sqlite3 db2 test.db
-  db2 eval {SELECT * FROM t1 ORDER BY 1}
-} {abc {} xyz abc}
-db2 close
-
-do_catchsql_test parser1-2.1 {
-  WITH RECURSIVE
-    c(x COLLATE binary) AS (VALUES(1) UNION SELECT x+1 FROM c WHERE x<5)
-  SELECT x FROM c;
-} {1 {syntax error after column name "x"}}
-do_catchsql_test parser1-2.2 {
-  WITH RECURSIVE
-    c(x ASC) AS (VALUES(1) UNION SELECT x+1 FROM c WHERE x<5)
-  SELECT x FROM c;
-} {1 {syntax error after column name "x"}}
-
-# Verify that the comma between multiple table constraints is
-# optional.
-#
-# The missing comma is technically a syntax error.  But we have to support
-# it because there might be legacy databases that omit the commas in their
-# sqlite_master tables.
-#
-do_execsql_test parser1-3.1 {
-  CREATE TABLE t300(id INTEGER PRIMARY KEY);
-  CREATE TABLE t301(
-    id INTEGER PRIMARY KEY,
-    c1 INTEGER NOT NULL,
-    c2 INTEGER NOT NULL,
-    c3 BOOLEAN NOT NULL DEFAULT 0,
-    FOREIGN KEY(c1) REFERENCES t300(id) ON DELETE CASCADE ON UPDATE RESTRICT
-        /* no comma */
-    FOREIGN KEY(c2) REFERENCES t300(id) ON DELETE CASCADE ON UPDATE RESTRICT
-        /* no comma */
-    UNIQUE(c1, c2)
-  );
-  PRAGMA foreign_key_list(t301);
-} {0 0 t300 c2 id RESTRICT CASCADE NONE 1 0 t300 c1 id RESTRICT CASCADE NONE}
-
-finish_test
@@ -239,4 +239,26 @@ do_execsql_test regexp1-2.22 {
  SELECT 'abc$¢€xyz' REGEXP '^abc[^\u0025-X][^ -\u007f][^\u20ab]xyz$'
 } {1}

+# 2022-07-03
+# https://sqlite.org/forum/forumpost/96692f8ba5
+# The REGEXP extension mishandles the prefix search optimization when
+# the prefix contains 3-byte UTF8 characters.
+#
+reset_db
+load_static_extension db regexp
+do_execsql_test regexp1-3.1 {
+  CREATE TABLE t1(id INTEGER PRIMARY KEY, a TEXT);
+  INSERT INTO t1(id, a) VALUES(1, '日本語');
+  SELECT a, hex(a), length(a) FROM t1;
+} {日本語 E697A5E69CACE8AA9E 3}
+do_execsql_test regexp1-3.2 {
+  SELECT * FROM t1 WHERE a='日本語';
+} {1 日本語}
+do_execsql_test regexp1-3.3 {
+  SELECT * FROM t1 WHERE a LIKE '日本語';
+} {1 日本語}
+do_execsql_test regexp1-3.4 {
+  SELECT * FROM t1 wHERE a REGEXP '日本語';
+} {1 日本語}
+
 finish_test
@@ -751,4 +751,35 @@ do_execsql_test 32.1 {
  WHERE a=1234 OR a<=567;
 } {500 502}

+# 2022-07-15
+# https://sqlite.org/forum/forumpost/3607259d3c
+#
+reset_db
+do_execsql_test 33.1 {
+  CREATE TABLE t1(a INT, b INT PRIMARY KEY) WITHOUT ROWID;
+  INSERT INTO t1(a, b) VALUES (0, 1),(15,-7),(3,100);
+  ANALYZE;
+} {}
+do_execsql_test 33.2 {
+  SELECT * FROM t1 WHERE (b,a) BETWEEN (0,5) AND (99,-2);
+} {0 1}
+do_execsql_test 33.3 {
+  SELECT * FROM t1 WHERE (b,a) BETWEEN (-8,5) AND (0,-2);
+} {15 -7}
+do_execsql_test 33.3 {
+  SELECT * FROM t1 WHERE (b,a) BETWEEN (3,5) AND (100,4);
+} {3 100}
+do_execsql_test 33.3 {
+  SELECT * FROM t1 WHERE (b,a) BETWEEN (3,5) AND (100,2);
+} {}
+do_execsql_test 33.3 {
+  SELECT * FROM t1 WHERE (a,b) BETWEEN (-2,99) AND (1,0);
+} {0 1}
+do_execsql_test 33.3 {
+  SELECT * FROM t1 WHERE (a,b) BETWEEN (14,99) AND (16,0);
+} {15 -7}
+do_execsql_test 33.3 {
+  SELECT * FROM t1 WHERE (a,b) BETWEEN (2,99) AND (4,0);
+} {3 100}
+
 finish_test
@@ -118,10 +118,18 @@ do_test select3-2.14 {
 } {1 {near ";": syntax error}}

 # Cannot have a HAVING without a GROUP BY
+# 
+# Update: As of 3.39.0, you can.
 #
 do_execsql_test select3-3.1 {
  SELECT log, count(*) FROM t1 HAVING log>=4
 } {}
+do_execsql_test select3-3.2 {
+  SELECT count(*) FROM t1 HAVING log>=4
+} {}
+do_execsql_test select3-3.3 {
+  SELECT count(*) FROM t1 HAVING log!=400
+} {31}

 # Toss in some HAVING clauses
 #
@@ -35,43 +35,6 @@ proc cond_incr_sync_count {adj} {
  }
 }

-proc set_tvfs_hdr {file args} {
-
-  # Set $nHdr to the number of bytes in the wal-index header:
-  set nHdr 48
-  set nInt [expr {$nHdr/4}]
-
-  if {[llength $args]>2} {
-    error {wrong # args: should be "set_tvfs_hdr fileName ?val1? ?val2?"}
-  }
-
-  set blob [tvfs shm $file]
-  if {$::tcl_platform(byteOrder)=="bigEndian"} {set fmt I} {set fmt i}
-
-  if {[llength $args]} {
-    set ia [lindex $args 0]
-    set ib $ia
-    if {[llength $args]==2} {
-      set ib [lindex $args 1]
-    }
-    binary scan $blob a[expr $nHdr*2]a* dummy tail
-    set blob [binary format ${fmt}${nInt}${fmt}${nInt}a* $ia $ib $tail]
-    tvfs shm $file $blob
-  }
-
-  binary scan $blob ${fmt}${nInt} ints
-  return $ints
-}
-
-proc incr_tvfs_hdr {file idx incrval} {
-  set ints [set_tvfs_hdr $file]
-  set v [lindex $ints $idx]
-  incr v $incrval
-  lset ints $idx $v
-  set_tvfs_hdr $file $ints
-}
-
-
 #-------------------------------------------------------------------------
 # Test case wal2-1.*:
 #
@@ -90,4 +90,44 @@ proc wal_fix_walindex_cksum {hdrvar} {
  lset hdr 11 $c2
 }

+# This command assumes that $file is the name of a database file opened
+# in wal mode using a [testvfs] VFS. It returns a list of the 12 32-bit
+# integers that make up the wal-index-header for the named file.
+#
+proc set_tvfs_hdr {file args} {
+
+  # Set $nHdr to the number of bytes in the wal-index header:
+  set nHdr 48
+  set nInt [expr {$nHdr/4}]
+
+  if {[llength $args]>2} {
+    error {wrong # args: should be "set_tvfs_hdr fileName ?val1? ?val2?"}
+  }
+
+  set blob [tvfs shm $file]
+  if {$::tcl_platform(byteOrder)=="bigEndian"} {set fmt I} {set fmt i}
+
+  if {[llength $args]} {
+    set ia [lindex $args 0]
+    set ib $ia
+    if {[llength $args]==2} {
+      set ib [lindex $args 1]
+    }
+    binary scan $blob a[expr $nHdr*2]a* dummy tail
+    set blob [binary format ${fmt}${nInt}${fmt}${nInt}a* $ia $ib $tail]
+    tvfs shm $file $blob
+  }
+
+  binary scan $blob ${fmt}${nInt} ints
+  return $ints
+}
+
+proc incr_tvfs_hdr {file idx incrval} {
+  set ints [set_tvfs_hdr $file]
+  set v [lindex $ints $idx]
+  incr v $incrval
+  lset ints $idx $v
+  set_tvfs_hdr $file $ints
+}
+

@@ -107,6 +107,12 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_FLAG_PRAGMAS)
  IF:   defined(SQLITE_DEBUG)

+  NAME: noop_update
+  TYPE: FLAG
+  ARG:  SQLITE_NoopUpdate
+  IF:   !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  IF:   defined(SQLITE_ENABLE_NOOP_UPDATE)
+
  NAME: ignore_check_constraints
  TYPE: FLAG
  ARG:  SQLITE_IgnoreChecks
@@ -1 +1 @@
 .39.0
 .39.3