Merge the 3.43.2 release changed into the reuse-schema-3.43 branch.

FossilOrigin-Name: 5fefa147ca4703e883670f0d65f8ea32c64474f1ca6a0d50d691cc677b987b71
Version 3.43.2
2023-10-10 13:55:07 +00:00 · 2023-10-10 12:14:04 +00:00 · 2023-10-09 22:50:30 +00:00 · 2023-10-09 14:59:42 +00:00 · 2023-10-09 14:12:44 +00:00 · 2023-10-09 14:10:07 +00:00
79 changed files with 3770 additions and 572 deletions
@@ -140,6 +140,7 @@ GCOV_LDFLAGS1 = -lgcov
 USE_GCOV = @USE_GCOV@
 LTCOMPILE_EXTRAS += $(GCOV_CFLAGS$(USE_GCOV))
 LTLINK_EXTRAS += $(GCOV_LDFLAGS$(USE_GCOV))
+LTCOMPILE_EXTRAS += -DSQLITE_ENABLE_SHARED_SCHEMA


 # The directory into which to store package information for
@@ -401,6 +402,7 @@ TESTSRC = \
  $(TOP)/src/test_quota.c \
  $(TOP)/src/test_rtree.c \
  $(TOP)/src/test_schema.c \
+  $(TOP)/src/test_schemapool.c \
  $(TOP)/src/test_superlock.c \
  $(TOP)/src/test_syscall.c \
  $(TOP)/src/test_tclsh.c \
@@ -465,6 +467,7 @@ TESTSRC2 = \
  $(TOP)/src/bitvec.c \
  $(TOP)/src/btree.c \
  $(TOP)/src/build.c \
+  $(TOP)/src/callback.c \
  $(TOP)/src/ctime.c \
  $(TOP)/src/date.c \
  $(TOP)/src/dbpage.c \
@@ -1312,17 +1315,23 @@ testrunner:	testfixture$(TEXE)

 # Runs both fuzztest and testrunner, consecutively.
 #
-devtest:	testfixture$(TEXE) fuzztest testrunner
+devtest:	srctree-check testfixture$(TEXE) fuzztest testrunner

-mdevtest:
+mdevtest: srctree-check
 	$(TCLSH_CMD) $(TOP)/test/testrunner.tcl mdevtest

 sdevtest:
 	$(TCLSH_CMD) $(TOP)/test/testrunner.tcl sdevtest

+# Validate that various generated files in the source tree
+# are up-to-date.
+#
+srctree-check:	$(TOP)/tool/srctree-check.tcl
+	$(TCLSH_CMD) $(TOP)/tool/srctree-check.tcl
+
 # Testing for a release
 #
-releasetest: testfixture$(TEXE)
+releasetest: srctree-check testfixture$(TEXE)
 	./testfixture$(TEXE) $(TOP)/test/testrunner.tcl release

 # Minimal testing that runs in less than 3 minutes
@@ -1333,7 +1342,7 @@ quicktest:	./testfixture$(TEXE)
 # This is the common case.  Run many tests that do not take too long,
 # including fuzzcheck, sqlite3_analyzer, and sqldiff tests.
 #
-test:	fuzztest sourcetest $(TESTPROGS) tcltest
+test:	srctree-check fuzztest sourcetest $(TESTPROGS) tcltest

 # Run a test using valgrind.  This can take a really long time
 # because valgrind is so much slower than a native machine.
@@ -1540,6 +1540,7 @@ TESTSRC = \
  $(TOP)\src\test_quota.c \
  $(TOP)\src\test_rtree.c \
  $(TOP)\src\test_schema.c \
+  $(TOP)\src\test_schemapool.c \
  $(TOP)\src\test_superlock.c \
  $(TOP)\src\test_syscall.c \
  $(TOP)\src\test_tclsh.c \
@@ -1 +1 @@
-3.43.0
+3.43.2
@@ -19,7 +19,7 @@ dnl	to configure the system for the local environment.
 # so that we create the export library with the dll.
 #-----------------------------------------------------------------------

-AC_INIT([sqlite],[3.43.0])
+AC_INIT([sqlite],[3.43.2])

 #--------------------------------------------------------------------
 # Call TEA_INIT as the first TEA_ macro to set up initial vars.
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for sqlite 3.43.0.
+# Generated by GNU Autoconf 2.69 for sqlite 3.43.2.
 #
 #
 # 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='3.43.0'
-PACKAGE_STRING='sqlite 3.43.0'
+PACKAGE_VERSION='3.43.2'
+PACKAGE_STRING='sqlite 3.43.2'
 PACKAGE_BUGREPORT=''
 PACKAGE_URL=''

@@ -1470,7 +1470,7 @@ 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 3.43.0 to adapt to many kinds of systems.
+\`configure' configures sqlite 3.43.2 to adapt to many kinds of systems.

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

@@ -1535,7 +1535,7 @@ fi

 if test -n "$ac_init_help"; then
  case $ac_init_help in
-     short | recursive ) echo "Configuration of sqlite 3.43.0:";;
+     short | recursive ) echo "Configuration of sqlite 3.43.2:";;
   esac
  cat <<\_ACEOF

@@ -1665,7 +1665,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
  cat <<\_ACEOF
-sqlite configure 3.43.0
+sqlite configure 3.43.2
 generated by GNU Autoconf 2.69

 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2084,7 +2084,7 @@ 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 3.43.0, which was
+It was created by sqlite $as_me 3.43.2, which was
 generated by GNU Autoconf 2.69.  Invocation command line was

  $ $0 $@
@@ -12457,7 +12457,7 @@ cat >>$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 3.43.0, which was
+This file was extended by sqlite $as_me 3.43.2, which was
 generated by GNU Autoconf 2.69.  Invocation command line was

  CONFIG_FILES    = $CONFIG_FILES
@@ -12523,7 +12523,7 @@ _ACEOF
 cat >>$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 3.43.0
+sqlite config.status 3.43.2
 configured by $0, generated by GNU Autoconf 2.69,
  with options \\"\$ac_cs_config\\"

@@ -0,0 +1,142 @@
+
+Shared-Schema Mode Notes
+========================
+
+The [reuse-schema](/timeline?r=reuse-schema) branch contains changes 
+to allow SQLite connections to share schemas
+between database connections within the same process in order to save memory.
+Schemas may be shared between multiple databases attached to the same or
+distinct connection handles.
+
+Compile with -DSQLITE\_ENABLE\_SHARED\_SCHEMA in order to enable the
+shared-schema enhancement.  Enabling the shared-schema enhancement causes
+approximately a 0.1% increase in CPU cycles consumed and about a 3000-byte
+increase in the size of the library, even if shared-schema is never used.
+
+Assuming the compile-time requirements are satisfied, the shared-schema
+feature is engaged by opening the database connection using the
+sqlite3&#95;open&#95;v2() API with the SQLITE&#95;OPEN&#95;SHARED&#95;SCHEMA
+flag specified.  The main database and any attached databases will then share
+an in-memory Schema object with any other database opened within the process
+for which: 
+
+  * the contents of the sqlite&#95;master table, including all object names,
+    SQL statements and root pages are identical, and
+  * have the same values for the schema-cookie.
+
+Temp databases (those populated with "CREATE TEMP TABLE" and similar
+statements) never share schemas.
+
+Connections opened with the SQLITE&#95;OPEN&#95;SHARED&#95;SCHEMA flag
+specified may not modify any database schema except that belonging to the
+temp database in anyway. This includes creating or dropping database 
+objects, vacuuming the database, or running ANALYZE when the
+sqlite&#95;stat\[14\] tables do not exist.
+
+For SQLITE&#95;OPEN&#95;SHARED&#95;SCHEMA connections, the
+SQLITE&#95;DBSTATUS&#95;SCHEMA&#95;USED sqlite3&#95;db&#95;status() verb
+distributes the memory used for a shared schema object evenly between all
+database connections that share it.
+
+## The ".shared-schema" Command
+
+The shell tool on this branch contains a special dot-command to help with
+managing databases. The ".shared-schema" dot-command can be used to test
+whether or not two databases are similar enough to share in-memory schemas,
+and to fix minor problems that prevent them from doing so. To test if
+two or more database are compatible, one database is opened directly using 
+the shell tool and the following command issued:
+
+        .shared-schema check <database-1> [<database-2>]...
+
+where &lt;database-1&gt; etc. are replaced with the names of database files
+on disk. For each database specified on the command line, a single line of
+output is produced. If the database can share an in-memory schema with the
+main database opened by the shell tool, the output is of the form:
+
+        <database> is compatible
+
+Otherwise, if the database cannot share a schema with the main db, the output
+is of the form:
+
+        <database> is NOT compatible (<reason>)
+
+where &lt;reason&gt; indicates the cause of the incompatibility. &lt;reason&gt;
+is always one of the following.
+
+<ul>
+  <li> <b>objects</b> - the databases contain a different set schema objects
+  (tables, indexes, views and triggers).
+
+  <li> <b>SQL</b> - the databases contain the same set of objects, but the SQL
+  statements used to create them were not the same.
+
+  <li> <b>root pages</b> - the databases contain the same set of objects created
+  by the same SQL statements, but the root pages are not the same.
+
+  <li> <b>order of sqlite&#95;master rows</b> - the databases contain the same
+  set of objects created by the same SQL statements with the same root pages,
+  but the order of the rows in the sqlite&#95;master tables are different.
+
+  <li> <b>schema cookie</b> - the database schemas are compatible, but the 
+  schema cookie values ("PRAGMA schema&#95;version") are different.
+</ul>
+
+The final three problems in the list above can be fixed using the
+.shared-schema command. To modify such a database so that it can share a 
+schema with the main database, the following shell command is used:
+
+        .shared-schema fix <database-1> [<database-2>]...
+
+If a database can be modified so that it may share a schema with the main
+database opened by the shell tool, output is as follows:
+
+        Fixing <database>... <database> is compatible
+
+If a database does not require modification, or cannot be modified such that
+it can share a schema with the main database, the output of "fix" is identical
+to that of the "check" command.
+
+## Implementation Notes
+
+A single Schema object is never used by more than one database simultaneously,
+regardless of whether or not those databases are attached to the same or
+different database handles. Instead, a pool of schema objects is maintained 
+for each unique sqlite&#95;master-contents/schema-cookie combination
+opened within the process. Each time database schemas are required by a
+connection, for example as part of an sqlite3&#95;prepare\*(),
+sqlite3&#95;blob&#95;open() or sqlite3&#95;blob&#95;open() call, it obtains
+the minimum number of schemas required from the various schema-pools, returning
+them at the end of the call. This means that a single schema-pool only ever
+contains more than one copy of the schema if:
+
+  * Two threads require schemas from the same pool at the same time, or
+  * A single sqlite3&#95;prepare\*() call requires schemas for two or more
+    attached databases that use the same schema-pool.
+
+The size of a schema-pool never shrinks. Each schema pool always maintains 
+a number of schema objects equal to the highwater mark of schema objects
+simultaneously required by clients.
+
+This approach is preferred to allowing multiple databases to use the same
+Schema object simultaneously for three reasons:
+
+  * The Schema object is not completely read-only. For example, the 
+    Index.zIdxAff string is allocated lazily.
+  * Throughout the statement compiler, SQLite uses variables like 
+    Table.pSchema and Index.pSchema with the sqlite3SchemaToIndex() routine
+    in order to determine which attached database a Table or Index object
+    resides in. This mechanism does not work if the same Schema may be
+    used by two or more attached databases.
+  * It may be easier to modify this approach in order to allow
+    SQLITE&#95;OPEN&#95;SHARED&#95;SCHEMA connections to modify database
+    schemas, should that be required.
+
+SQLITE&#95;OPEN&#95;SHARED&#95;SCHEMA connections do not store their
+virtual-table handles in the Table.pVTable list of each table. This would not
+work, as (a) there is no guarantee that a connection will be assigned the same
+Schema object each time it requests one from a schema-pool and (b) a single
+Schema (and therefore Table) object may correspond to tables in two or more
+databases attached to a single connection. Instead, all virtual-table handles
+associated with a single database are stored in a linked-list headed at
+Db.pVTable.
@@ -5218,7 +5218,7 @@ static u64 fts3ChecksumIndex(
  int rc;
  u64 cksum = 0;

-  assert( *pRc==SQLITE_OK );
+  if( *pRc ) return 0;

  memset(&filter, 0, sizeof(filter));
  memset(&csr, 0, sizeof(csr));
@@ -5057,7 +5057,6 @@ static void fts5DoSecureDelete(
  int iIdx = 0;
  int iStart = 0;
  int iKeyOff = 0;
-  int iPrevKeyOff = 0;
  int iDelKeyOff = 0;       /* Offset of deleted key, if any */

  nIdx = nPg-iPgIdx;
@@ -5198,80 +5197,79 @@ static void fts5DoSecureDelete(
      }
    }
  }else if( iStart==4 ){
-      int iPgno;
+    int iPgno;

-      assert_nc( pSeg->iLeafPgno>pSeg->iTermLeafPgno );
-      /* The entry being removed may be the only position list in
-      ** its doclist. */
-      for(iPgno=pSeg->iLeafPgno-1; iPgno>pSeg->iTermLeafPgno; iPgno-- ){
-        Fts5Data *pPg = fts5DataRead(p, FTS5_SEGMENT_ROWID(iSegid, iPgno));
-        int bEmpty = (pPg && pPg->nn==4);
-        fts5DataRelease(pPg);
-        if( bEmpty==0 ) break;
-      }
+    assert_nc( pSeg->iLeafPgno>pSeg->iTermLeafPgno );
+    /* The entry being removed may be the only position list in
+    ** its doclist. */
+    for(iPgno=pSeg->iLeafPgno-1; iPgno>pSeg->iTermLeafPgno; iPgno-- ){
+      Fts5Data *pPg = fts5DataRead(p, FTS5_SEGMENT_ROWID(iSegid, iPgno));
+      int bEmpty = (pPg && pPg->nn==4);
+      fts5DataRelease(pPg);
+      if( bEmpty==0 ) break;
+    }

-      if( iPgno==pSeg->iTermLeafPgno ){
-        i64 iId = FTS5_SEGMENT_ROWID(iSegid, pSeg->iTermLeafPgno);
-        Fts5Data *pTerm = fts5DataRead(p, iId);
-        if( pTerm && pTerm->szLeaf==pSeg->iTermLeafOffset ){
-          u8 *aTermIdx = &pTerm->p[pTerm->szLeaf];
-          int nTermIdx = pTerm->nn - pTerm->szLeaf;
-          int iTermIdx = 0;
-          int iTermOff = 0;
+    if( iPgno==pSeg->iTermLeafPgno ){
+      i64 iId = FTS5_SEGMENT_ROWID(iSegid, pSeg->iTermLeafPgno);
+      Fts5Data *pTerm = fts5DataRead(p, iId);
+      if( pTerm && pTerm->szLeaf==pSeg->iTermLeafOffset ){
+        u8 *aTermIdx = &pTerm->p[pTerm->szLeaf];
+        int nTermIdx = pTerm->nn - pTerm->szLeaf;
+        int iTermIdx = 0;
+        int iTermOff = 0;

-          while( 1 ){
-            u32 iVal = 0;
-            int nByte = fts5GetVarint32(&aTermIdx[iTermIdx], iVal);
-            iTermOff += iVal;
-            if( (iTermIdx+nByte)>=nTermIdx ) break;
-            iTermIdx += nByte;
-          }
-          nTermIdx = iTermIdx;
-
-          memmove(&pTerm->p[iTermOff], &pTerm->p[pTerm->szLeaf], nTermIdx);
-          fts5PutU16(&pTerm->p[2], iTermOff);
-
-          fts5DataWrite(p, iId, pTerm->p, iTermOff+nTermIdx);
-          if( nTermIdx==0 ){
-            fts5SecureDeleteIdxEntry(p, iSegid, pSeg->iTermLeafPgno);
-          }
+        while( 1 ){
+          u32 iVal = 0;
+          int nByte = fts5GetVarint32(&aTermIdx[iTermIdx], iVal);
+          iTermOff += iVal;
+          if( (iTermIdx+nByte)>=nTermIdx ) break;
+          iTermIdx += nByte;
        }
-        fts5DataRelease(pTerm);
+        nTermIdx = iTermIdx;
+
+        memmove(&pTerm->p[iTermOff], &pTerm->p[pTerm->szLeaf], nTermIdx);
+        fts5PutU16(&pTerm->p[2], iTermOff);
+
+        fts5DataWrite(p, iId, pTerm->p, iTermOff+nTermIdx);
+        if( nTermIdx==0 ){
+          fts5SecureDeleteIdxEntry(p, iSegid, pSeg->iTermLeafPgno);
+        }
+      }
+      fts5DataRelease(pTerm);
+    }
+  }
+
+  if( p->rc==SQLITE_OK ){
+    const int nMove = nPg - iNextOff;     /* Number of bytes to move */
+    int nShift = iNextOff - iOff;         /* Distance to move them */
+
+    int iPrevKeyOut = 0;
+    int iKeyIn = 0;
+
+    memmove(&aPg[iOff], &aPg[iNextOff], nMove);
+    iPgIdx -= nShift;
+    nPg = iPgIdx;
+    fts5PutU16(&aPg[2], iPgIdx);
+
+    for(iIdx=0; iIdx<nIdx; /* no-op */){
+      u32 iVal = 0;
+      iIdx += fts5GetVarint32(&aIdx[iIdx], iVal);
+      iKeyIn += iVal;
+      if( iKeyIn!=iDelKeyOff ){
+        int iKeyOut = (iKeyIn - (iKeyIn>iOff ? nShift : 0));
+        nPg += sqlite3Fts5PutVarint(&aPg[nPg], iKeyOut - iPrevKeyOut);
+        iPrevKeyOut = iKeyOut;
      }
    }

-    if( p->rc==SQLITE_OK ){
-      const int nMove = nPg - iNextOff;
-      int nShift = 0;
-
-      memmove(&aPg[iOff], &aPg[iNextOff], nMove);
-      iPgIdx -= (iNextOff - iOff);
-      nPg = iPgIdx;
-      fts5PutU16(&aPg[2], iPgIdx);
-
-      nShift = iNextOff - iOff;
-      for(iIdx=0, iKeyOff=0, iPrevKeyOff=0; iIdx<nIdx; /* no-op */){
-        u32 iVal = 0;
-        iIdx += fts5GetVarint32(&aIdx[iIdx], iVal);
-        iKeyOff += iVal;
-        if( iKeyOff!=iDelKeyOff ){
-          if( iKeyOff>iOff ){
-            iKeyOff -= nShift;
-            nShift = 0;
-          }
-          nPg += sqlite3Fts5PutVarint(&aPg[nPg], iKeyOff - iPrevKeyOff);
-          iPrevKeyOff = iKeyOff;
-        }
-      }
-
-      if( iPgIdx==nPg && nIdx>0 && pSeg->iLeafPgno!=1 ){
-        fts5SecureDeleteIdxEntry(p, iSegid, pSeg->iLeafPgno);
-      }
-
-      assert_nc( nPg>4 || fts5GetU16(aPg)==0 );
-      fts5DataWrite(p, FTS5_SEGMENT_ROWID(iSegid,pSeg->iLeafPgno), aPg,nPg);
+    if( iPgIdx==nPg && nIdx>0 && pSeg->iLeafPgno!=1 ){
+      fts5SecureDeleteIdxEntry(p, iSegid, pSeg->iLeafPgno);
    }
-    sqlite3_free(aIdx);
+
+    assert_nc( nPg>4 || fts5GetU16(aPg)==0 );
+    fts5DataWrite(p, FTS5_SEGMENT_ROWID(iSegid,pSeg->iLeafPgno), aPg, nPg);
+  }
+  sqlite3_free(aIdx);
 }

 /*
@@ -1329,6 +1329,9 @@ static int fts5FilterMethod(
    pCsr->iFirstRowid = fts5GetRowidLimit(pRowidGe, SMALLEST_INT64);
  }

+  rc = sqlite3Fts5IndexLoadConfig(pTab->p.pIndex);
+  if( rc!=SQLITE_OK ) goto filter_out;
+
  if( pTab->pSortCsr ){
    /* If pSortCsr is non-NULL, then this call is being made as part of 
    ** processing for a "... MATCH <expr> ORDER BY rank" query (ePlan is
@@ -1351,7 +1354,9 @@ static int fts5FilterMethod(
    pCsr->pExpr = pTab->pSortCsr->pExpr;
    rc = fts5CursorFirst(pTab, pCsr, bDesc);
  }else if( pCsr->pExpr ){
-    rc = fts5CursorParseRank(pConfig, pCsr, pRank);
+    if( rc==SQLITE_OK ){
+      rc = fts5CursorParseRank(pConfig, pCsr, pRank);
+    }
    if( rc==SQLITE_OK ){
      if( bOrderByRank ){
        pCsr->ePlan = FTS5_PLAN_SORTED_MATCH;
@@ -44,12 +44,12 @@ do_catchsql_test 1.2.2 {

 do_catchsql_test 1.3.1 { 
  SELECT highlight(t1, 4, '<b>', '</b>') FROM t1('*reads'); 
-} {1 {no such cursor: 1}}
+} {1 {no such cursor: 2}}

 do_catchsql_test 1.3.2 {
  SELECT a FROM t1
    WHERE rank = (SELECT highlight(t1, 4, '<b>', '</b>') FROM t1('*reads'));
-} {1 {no such cursor: 1}}
+} {1 {no such cursor: 2}}

 db close
 sqlite3 db test.db
@@ -180,4 +180,28 @@ do_execsql_test 6.1 {
  {table table table} {the table names.} {rank on an fts5 table}
 }

+
+#-------------------------------------------------------------------------
+# forum post: https://sqlite.org/forum/forumpost/a2dd636330
+#
+reset_db
+do_execsql_test 1.0 {
+  CREATE VIRTUAL TABLE t USING fts5 (a, b);  
+  INSERT INTO t (a, b) VALUES ('data1', 'sentence1'), ('data2', 'sentence2'); 
+  INSERT INTO t(t, rank) VALUES ('rank', 'bm25(10.0,1.0)');
+}
+
+sqlite3 db2 test.db 
+do_execsql_test -db db2 1.1 {
+  SELECT *, rank<0.0 FROM t('data*') ORDER BY RANK;
+} {data1 sentence1 1 data2 sentence2 1}
+
+do_execsql_test 1.2 {
+  INSERT INTO t(t, rank) VALUES ('rank', 'bm25(10.0,1.0)');
+}
+do_execsql_test -db db2 1.3 {
+  SELECT *, rank<0.0 FROM t('data*') ORDER BY RANK;
+} {data1 sentence1 1 data2 sentence2 1}
+db2 close
+
 finish_test
@@ -273,6 +273,19 @@ do_execsql_test 5.3 {
 do_execsql_test 5.4 { SELECT rowid FROM t1('abc'); } 2
 do_execsql_test 5.5 { SELECT rowid FROM t1('aa'); } 2

+#-------------------------------------------------------------------------
+reset_db
+
+do_execsql_test 6.0 {
+  CREATE VIRTUAL TABLE fts USING fts5(content);
+  INSERT INTO fts(fts, rank) VALUES ('secure-delete', 1);
+  INSERT INTO fts(rowid, content) VALUES
+    (3407, 'profile profile profile profile profile profile profile profile pull pulling pulling really');
+  DELETE FROM fts WHERE rowid IS 3407;
+  INSERT INTO fts(fts) VALUES ('integrity-check');
+}
+
+

 finish_test

@@ -3236,15 +3236,19 @@ static int sessionReadRecord(
        }
      }
      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
-        sqlite3_int64 v = sessionGetI64(aVal);
-        if( eType==SQLITE_INTEGER ){
-          sqlite3VdbeMemSetInt64(apOut[i], v);
+        if( (pIn->nData-pIn->iNext)<8 ){
+          rc = SQLITE_CORRUPT_BKPT;
        }else{
-          double d;
-          memcpy(&d, &v, 8);
-          sqlite3VdbeMemSetDouble(apOut[i], d);
+          sqlite3_int64 v = sessionGetI64(aVal);
+          if( eType==SQLITE_INTEGER ){
+            sqlite3VdbeMemSetInt64(apOut[i], v);
+          }else{
+            double d;
+            memcpy(&d, &v, 8);
+            sqlite3VdbeMemSetDouble(apOut[i], d);
+          }
+          pIn->iNext += 8;
        }
-        pIn->iNext += 8;
      }
    }
  }
@@ -1,10 +1,7 @@
+_fiddle_exec
+_fiddle_interrupt
+_fiddle_experiment
+_fiddle_the_db
 _fiddle_db_arg
 _fiddle_db_filename
-_fiddle_exec
-_fiddle_experiment
-_fiddle_interrupt
-_fiddle_main
 _fiddle_reset_db
-_fiddle_db_handle
-_fiddle_db_vfs
-_fiddle_export_db
@@ -845,11 +845,11 @@ sqlite3-worker1-bundler-friendly.js := $(dir.dout)/sqlite3-worker1-bundler-frien
 sqlite3-worker1-promiser-bundler-friendly.js := $(dir.dout)/sqlite3-worker1-promiser-bundler-friendly.js
 $(eval $(call C-PP.FILTER,$(sqlite3-worker1.js.in),$(sqlite3-worker1.js)))
 $(eval $(call C-PP.FILTER,$(sqlite3-worker1.js.in),$(sqlite3-worker1-bundler-friendly.js),\
-    $(c-pp.D.bundler-friendly)))
+    $(c-pp.D.sqlite3-bundler-friendly)))
 $(eval $(call C-PP.FILTER,$(sqlite3-worker1-promiser.js.in),$(sqlite3-worker1-promiser.js)))
 $(eval $(call C-PP.FILTER,$(sqlite3-worker1-promiser.js.in),\
    $(sqlite3-worker1-promiser-bundler-friendly.js),\
-    $(c-pp.D.bundler-friendly)))
+    $(c-pp.D.sqlite3-bundler-friendly)))
 $(sqlite3-bundler-friendly.mjs): $(sqlite3-worker1-bundler-friendly.js) \
    $(sqlite3-worker1-promiser-bundler-friendly.js)
 $(sqlite3.js) $(sqlite3.mjs): $(sqlite3-worker1.js) $(sqlite3-worker1-promiser.js)
@@ -1,8 +1,3 @@
-_malloc
-_free
-_realloc
-_sqlite3_aggregate_context
-_sqlite3_auto_extension
 _sqlite3_bind_blob
 _sqlite3_bind_double
 _sqlite3_bind_int
@@ -10,16 +5,11 @@ _sqlite3_bind_int64
 _sqlite3_bind_null
 _sqlite3_bind_parameter_count
 _sqlite3_bind_parameter_index
-_sqlite3_bind_pointer
 _sqlite3_bind_text
-_sqlite3_busy_handler
-_sqlite3_busy_timeout
-_sqlite3_cancel_auto_extension
 _sqlite3_changes
 _sqlite3_changes64
 _sqlite3_clear_bindings
 _sqlite3_close_v2
-_sqlite3_collation_needed
 _sqlite3_column_blob
 _sqlite3_column_bytes
 _sqlite3_column_count
@@ -30,28 +20,12 @@ _sqlite3_column_int64
 _sqlite3_column_name
 _sqlite3_column_text
 _sqlite3_column_type
-_sqlite3_column_value
-_sqlite3_commit_hook
 _sqlite3_compileoption_get
 _sqlite3_compileoption_used
-_sqlite3_complete
-_sqlite3_context_db_handle
-_sqlite3_create_collation
-_sqlite3_create_collation_v2
-_sqlite3_create_function
 _sqlite3_create_function_v2
-_sqlite3_create_module
-_sqlite3_create_module_v2
-_sqlite3_create_window_function
 _sqlite3_data_count
 _sqlite3_db_filename
-_sqlite3_db_handle
 _sqlite3_db_name
-_sqlite3_db_status
-_sqlite3_declare_vtab
-_sqlite3_deserialize
-_sqlite3_drop_modules
-_sqlite3_errcode
 _sqlite3_errmsg
 _sqlite3_error_offset
 _sqlite3_errstr
@@ -59,38 +33,16 @@ _sqlite3_exec
 _sqlite3_expanded_sql
 _sqlite3_extended_errcode
 _sqlite3_extended_result_codes
-_sqlite3_file_control
 _sqlite3_finalize
-_sqlite3_free
-_sqlite3_get_auxdata
 _sqlite3_initialize
-_sqlite3_keyword_count
-_sqlite3_keyword_name
-_sqlite3_keyword_check
-_sqlite3_last_insert_rowid
+_sqlite3_interrupt
 _sqlite3_libversion
 _sqlite3_libversion_number
-_sqlite3_limit
-_sqlite3_malloc
-_sqlite3_malloc64
-_sqlite3_msize
 _sqlite3_open
 _sqlite3_open_v2
-_sqlite3_overload_function
 _sqlite3_prepare_v2
 _sqlite3_prepare_v3
-_sqlite3_preupdate_blobwrite
-_sqlite3_preupdate_count
-_sqlite3_preupdate_depth
-_sqlite3_preupdate_hook
-_sqlite3_preupdate_new
-_sqlite3_preupdate_old
-_sqlite3_progress_handler
-_sqlite3_randomness
-_sqlite3_realloc
-_sqlite3_realloc64
 _sqlite3_reset
-_sqlite3_reset_auto_extension
 _sqlite3_result_blob
 _sqlite3_result_double
 _sqlite3_result_error
@@ -98,106 +50,23 @@ _sqlite3_result_error_code
 _sqlite3_result_error_nomem
 _sqlite3_result_error_toobig
 _sqlite3_result_int
-_sqlite3_result_int64
 _sqlite3_result_null
-_sqlite3_result_pointer
-_sqlite3_result_subtype
 _sqlite3_result_text
-_sqlite3_result_zeroblob
-_sqlite3_result_zeroblob64
-_sqlite3_rollback_hook
-_sqlite3_serialize
-_sqlite3_set_authorizer
-_sqlite3_set_auxdata
-_sqlite3_set_last_insert_rowid
-_sqlite3_shutdown
 _sqlite3_sourceid
 _sqlite3_sql
-_sqlite3_status
-_sqlite3_status64
 _sqlite3_step
-_sqlite3_stmt_isexplain
-_sqlite3_stmt_readonly
-_sqlite3_stmt_status
 _sqlite3_strglob
-_sqlite3_stricmp
 _sqlite3_strlike
-_sqlite3_strnicmp
-_sqlite3_table_column_metadata
 _sqlite3_total_changes
 _sqlite3_total_changes64
-_sqlite3_trace_v2
-_sqlite3_txn_state
-_sqlite3_update_hook
-_sqlite3_uri_boolean
-_sqlite3_uri_int64
-_sqlite3_uri_key
-_sqlite3_uri_parameter
-_sqlite3_user_data
 _sqlite3_value_blob
 _sqlite3_value_bytes
 _sqlite3_value_double
-_sqlite3_value_dup
-_sqlite3_value_free
-_sqlite3_value_frombind
-_sqlite3_value_int
-_sqlite3_value_int64
-_sqlite3_value_nochange
-_sqlite3_value_numeric_type
-_sqlite3_value_pointer
-_sqlite3_value_subtype
 _sqlite3_value_text
 _sqlite3_value_type
 _sqlite3_vfs_find
 _sqlite3_vfs_register
-_sqlite3_vfs_unregister
-_sqlite3_vtab_collation
-_sqlite3_vtab_distinct
-_sqlite3_vtab_in
-_sqlite3_vtab_in_first
-_sqlite3_vtab_in_next
-_sqlite3_vtab_nochange
-_sqlite3_vtab_on_conflict
-_sqlite3_vtab_rhs_value
-_sqlite3changegroup_add
-_sqlite3changegroup_add_strm
-_sqlite3changegroup_delete
-_sqlite3changegroup_new
-_sqlite3changegroup_output
-_sqlite3changegroup_output_strm
-_sqlite3changeset_apply
-_sqlite3changeset_apply_strm
-_sqlite3changeset_apply_v2
-_sqlite3changeset_apply_v2_strm
-_sqlite3changeset_concat
-_sqlite3changeset_concat_strm
-_sqlite3changeset_conflict
-_sqlite3changeset_finalize
-_sqlite3changeset_fk_conflicts
-_sqlite3changeset_invert
-_sqlite3changeset_invert_strm
-_sqlite3changeset_new
-_sqlite3changeset_next
-_sqlite3changeset_old
-_sqlite3changeset_op
-_sqlite3changeset_pk
-_sqlite3changeset_start
-_sqlite3changeset_start_strm
-_sqlite3changeset_start_v2
-_sqlite3changeset_start_v2_strm
-_sqlite3session_attach
-_sqlite3session_changeset
-_sqlite3session_changeset_size
-_sqlite3session_changeset_strm
-_sqlite3session_config
-_sqlite3session_create
-_sqlite3session_delete
-_sqlite3session_diff
-_sqlite3session_enable
-_sqlite3session_indirect
-_sqlite3session_isempty
-_sqlite3session_memory_used
-_sqlite3session_object_config
-_sqlite3session_patchset
-_sqlite3session_patchset_strm
-_sqlite3session_table_filter
+_sqlite3_wasm_db_error
+_sqlite3_wasm_enum_json
+_malloc
+_free
@@ -888,9 +888,9 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
     consistency with non-special-case wrappings.
  */
  const __dbArgcMismatch = (pDb,f,n)=>{
-    return sqlite3.util.sqlite3_wasm_db_error(pDb, capi.SQLITE_MISUSE,
-                                              f+"() requires "+n+" argument"+
-                                              (1===n?"":'s')+".");
+    return util.sqlite3_wasm_db_error(pDb, capi.SQLITE_MISUSE,
+                                      f+"() requires "+n+" argument"+
+                                      (1===n?"":'s')+".");
  };

  /** Code duplication reducer for functions which take an encoding
@@ -890,6 +890,8 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
        this.setAssociatedPath(sah, '', 0);
        toss("Expected to write "+n+" bytes but wrote "+nWrote+".");
      }else{
+        sah.write(new Uint8Array([1,1]), {at: HEADER_OFFSET_DATA+18}
+                  /* force db out of WAL mode */);
        this.setAssociatedPath(sah, name, capi.SQLITE_OPEN_MAIN_DB);
      }
    }
@@ -1192,16 +1192,25 @@ const installOpfsVfs = function callee(options){
          toss("Input does not contain an SQLite database header.");
        }
      }
+      let sah;
      const [hDir, fnamePart] = await opfsUtil.getDirForFilename(filename, true);
-      const hFile = await hDir.getFileHandle(fnamePart, {create:true});
-      const sah = await hFile.createSyncAccessHandle();
-      sah.truncate(0);
-      const nWrote = sah.write(bytes, {at: 0});
-      sah.close();
-      if(nWrote != n){
-        toss("Expected to write "+n+" bytes but wrote "+nWrote+".");
+      try {
+        const hFile = await hDir.getFileHandle(fnamePart, {create:true});
+        sah = await hFile.createSyncAccessHandle();
+        sah.truncate(0);
+        const nWrote = sah.write(bytes, {at: 0});
+        if(nWrote != n){
+          toss("Expected to write "+n+" bytes but wrote "+nWrote+".");
+        }
+        sah.write(new Uint8Array([1,1]), {at: 18}) /* force db out of WAL mode */;
+        return nWrote;
+      }catch(e){
+        if( sah ){ await sah.close(); sah = undefined; }
+        await hDir.removeEntry( fnamePart ).catch(()=>{});
+        throw e;
+      }finally{
+        if( sah ) await sah.close();
      }
-      return nWrote;
    };

    if(sqlite3.oo1){
@@ -114,7 +114,7 @@
   by all client code except that which tests this API. The `row`
   property contains the row result in the form implied by the
   `rowMode` option (defaulting to `'array'`). The `rowNumber` is a
-   1-based integer value incremented by 1 on each call into the
+   1-based integer value incremented by 1 on each call into th 
   callback.

   At the end of the result set, the same event is fired with
@@ -122,17 +122,8 @@
   the end of the result set has been reached. Note that the rows
   arrive via worker-posted messages, with all the implications
   of that.
-
-   Notable shortcomings:
-
-   - This API was not designed with ES6 modules in mind. Neither Firefox
-     nor Safari support, as of March 2023, the {type:"module"} flag to the
-     Worker constructor, so that particular usage is not something we're going
-     to target for the time being:
-
-     https://developer.mozilla.org/en-US/docs/Web/API/Worker/Worker
 */
-globalThis.sqlite3Worker1Promiser = function callee(config = callee.defaultConfig){
+self.sqlite3Worker1Promiser = function callee(config = callee.defaultConfig){
  // Inspired by: https://stackoverflow.com/a/52439530
  if(1===arguments.length && 'function'===typeof arguments[0]){
    const f = config;
@@ -169,7 +160,7 @@ globalThis.sqlite3Worker1Promiser = function callee(config = callee.defaultConfi
      if(msgHandler && msgHandler.onrow){
        msgHandler.onrow(ev);
        return;
-      }
+      }        
      if(config.onunhandled) config.onunhandled(arguments[0]);
      else err("sqlite3Worker1Promiser() unhandled worker message:",ev);
      return;
@@ -196,9 +187,10 @@ globalThis.sqlite3Worker1Promiser = function callee(config = callee.defaultConfi
    if(1===arguments.length){
      msg = arguments[0];
    }else if(2===arguments.length){
-      msg = Object.create(null);
-      msg.type = arguments[0];
-      msg.args = arguments[1];
+      msg = {
+        type: arguments[0],
+        args: arguments[1]
+      };
    }else{
      toss("Invalid arugments for sqlite3Worker1Promiser()-created factory.");
    }
@@ -244,13 +236,10 @@ globalThis.sqlite3Worker1Promiser = function callee(config = callee.defaultConfi
    return p;
  };
 }/*sqlite3Worker1Promiser()*/;
-globalThis.sqlite3Worker1Promiser.defaultConfig = {
+self.sqlite3Worker1Promiser.defaultConfig = {
  worker: function(){
 //#if target=es6-bundler-friendly
-    return new Worker("sqlite3-worker1-bundler-friendly.mjs",{
-      type: 'module' /* Noting that neither Firefox nor Safari suppor this,
-                        as of this writing. */
-    });
+    return new Worker("sqlite3-worker1.js");
 //#else
    let theJs = "sqlite3-worker1.js";
    if(this.currentScript){
@@ -258,17 +247,17 @@ globalThis.sqlite3Worker1Promiser.defaultConfig = {
      src.pop();
      theJs = src.join('/')+'/' + theJs;
      //sqlite3.config.warn("promiser currentScript, theJs =",this.currentScript,theJs);
-    }else if(globalThis.location){
-      //sqlite3.config.warn("promiser globalThis.location =",globalThis.location);
-      const urlParams = new URL(globalThis.location.href).searchParams;
+    }else{
+      //sqlite3.config.warn("promiser self.location =",self.location);
+      const urlParams = new URL(self.location.href).searchParams;
      if(urlParams.has('sqlite3.dir')){
        theJs = urlParams.get('sqlite3.dir') + '/' + theJs;
      }
    }
-    return new Worker(theJs + globalThis.location.search);
+    return new Worker(theJs + self.location.search);
 //#endif
  }.bind({
-    currentScript: globalThis?.document?.currentScript
+    currentScript: self?.document?.currentScript
  }),
  onerror: (...args)=>console.error('worker1 promiser error',...args)
 };
@@ -273,6 +273,11 @@
        </fieldset>
      </div>
    </div> <!-- #view-split -->
+    <!-- Maintenance notes:
+
+        ... TODO... currently being refactored...
+
+    -->
    <script src="fiddle.js"></script>
  </body>
 </html>
@@ -326,6 +326,7 @@ TESTSRC = \
  $(TOP)/src/test_quota.c \
  $(TOP)/src/test_rtree.c \
  $(TOP)/src/test_schema.c \
+  $(TOP)/src/test_schemapool.c \
  $(TOP)/src/test_sqllog.c \
  $(TOP)/src/test_superlock.c \
  $(TOP)/src/test_syscall.c \
@@ -384,6 +385,7 @@ TESTSRC2 = \
  $(TOP)/src/backup.c \
  $(TOP)/src/btree.c \
  $(TOP)/src/build.c \
+  $(TOP)/src/callback.c \
  $(TOP)/src/date.c \
  $(TOP)/src/dbpage.c \
  $(TOP)/src/dbstat.c \
@@ -1,13 +1,13 @@
-C Version\s3.43.0
-D 2023-08-24T12:36:59.632
+C Merge\sthe\s3.43.2\srelease\schanged\sinto\sthe\sreuse-schema-3.43\sbranch.
+D 2023-10-10T13:55:07.125
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
-F Makefile.in 1e9105ffed727b1557ce59f0941c5d271e276ec00bc9823f03d77a89e131b918
+F Makefile.in 9a778ee7f4c02fdd742a80f690830059a5ff8afcae557212666502e9d6dc619b
 F Makefile.linux-gcc f3842a0b1efbfbb74ac0ef60e56b301836d05b4d867d014f714fa750048f1ab6
-F Makefile.msc 26c2d196391a285c279adb10fd6001774d9b243af94b700b681e4a49cd476684
+F Makefile.msc dc507b7af6d6d82ebdaaa17fd55f33e31d950933aa6e38a8c5d9e2cc1336c2d2
 F README.md 963d30019abf0cc06b263cd2824bce022893f3f93a531758f6f04ff2194a16a8
-F VERSION c6366dc72582d3144ce87b013cc35fe48d62f6d07d5be0c9716ea33c862144aa
+F VERSION 56b287eac8404526c4faa0bdfa7e31baed534068fa3acece479b5d6c35cfca1e
 F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
 F art/sqlite370.eps aa97a671332b432a54e1d74ff5e8775be34200c2
 F art/sqlite370.ico af56c1d00fee7cd4753e8631ed60703ed0fc6e90
@@ -22,7 +22,7 @@ F autoconf/configure.ac ec7fa914c5e74ff212fe879f9bb6918e1234497e05facfb641f30c4d
 F autoconf/tea/Makefile.in 106a96f2f745d41a0f6193f1de98d7355830b65d45032c18cd7c90295ec24196
 F autoconf/tea/README 3e9a3c060f29a44344ab50aec506f4db903fb873
 F autoconf/tea/aclocal.m4 52c47aac44ce0ddb1f918b6993e8beb8eee88f43
-F autoconf/tea/configure.ac fce5eca183cf47853f7d5b81c1e7bfa41c021fb460939ec67ef83653ffc6a531
+F autoconf/tea/configure.ac c968ba373f2afaad123e59e14baf20aa423ac0e5668ca8b40092b96b408d9938
 F autoconf/tea/doc/sqlite3.n e1fe45d4f5286ee3d0ccc877aca2a0def488e9bb
 F autoconf/tea/license.terms 13bd403c9610fd2b76ece0ab50c4c5eda933d523
 F autoconf/tea/pkgIndex.tcl.in b9eb6dd37f64e08e637d576b3c83259814b9cddd78bec4af2e5abfc6c5c750ce
@@ -33,7 +33,7 @@ F autoconf/tea/win/nmakehlp.c b01f822eabbe1ed2b64e70882d97d48402b42d2689a1ea0034
 F autoconf/tea/win/rules.vc c511f222b80064096b705dbeb97060ee1d6b6d63
 F config.guess 883205ddf25b46f10c181818bf42c09da9888884af96f79e1719264345053bd6
 F config.sub c2d0260f17f3e4bc0b6808fccf1b291cb5e9126c14fc5890efc77b9fd0175559
-F configure 9dc3300339f4d6b3c3b108de60cc6ae6b3c547e25c7e6df280b4775db4de3a1b x
+F configure 2c538b418bb71f7e8bb62193eae709a1f7dd4342f74f6530891bd1e937c03df2 x
 F configure.ac 4654d32ac0a0d0b48f1e1e79bdc3d777b723cf2f63c33eb1d7c4ed8b435938e8
 F contrib/sqlitecon.tcl 210a913ad63f9f991070821e599d600bd913e0ad
 F doc/F2FS.txt c1d4a0ae9711cfe0e1d8b019d154f1c29e0d3abfe820787ba1e9ed7691160fcd
@@ -41,6 +41,7 @@ F doc/compile-for-windows.md c52f2903f1cb11b2308798feecca2e44701b037b78f467a538a
 F doc/json-enhancements.md e356fc834781f1f1aa22ee300027a270b2c960122468499bf347bb123ce1ea4f
 F doc/lemon.html 44a53a1d2b42d7751f7b2f478efb23c978e258d794bfd172442307a755b9fa44
 F doc/pager-invariants.txt 27fed9a70ddad2088750c4a2b493b63853da2710
+F doc/shared_schema.md 759fc374709fccf4e5d2d0cbd05f8fedd38fb022bdd8a6c5b5f492684c7023b9
 F doc/trusted-schema.md 33625008620e879c7bcfbbfa079587612c434fa094d338b08242288d358c3e8a
 F doc/vdbesort-memory.md 4da2639c14cd24a31e0af694b1a8dd37eaf277aff3867e9a8cc14046bc49df56
 F doc/vfs-shm.txt e101f27ea02a8387ce46a05be2b1a902a021d37a
@@ -77,7 +78,7 @@ F ext/fts3/fts3_tokenizer.h 64c6ef6c5272c51ebe60fc607a896e84288fcbc3
 F ext/fts3/fts3_tokenizer1.c c1de4ae28356ad98ccb8b2e3388a7fdcce7607b5523738c9afb6275dab765154
 F ext/fts3/fts3_unicode.c de426ff05c1c2e7bce161cf6b706638419c3a1d9c2667de9cb9dc0458c18e226
 F ext/fts3/fts3_unicode2.c 416eb7e1e81142703520d284b768ca2751d40e31fa912cae24ba74860532bf0f
-F ext/fts3/fts3_write.c d28d9ef383ef848a7b77df4b9964abcc90d67a2b584120c0ad465972dce416e6
+F ext/fts3/fts3_write.c b28f4cde90ed560245ecb76a882b45aa62da16ff6f61e9884eae5c7c5eff16ea
 F ext/fts3/fts3speed.tcl b54caf6a18d38174f1a6e84219950d85e98bb1e9
 F ext/fts3/tool/fts3cov.sh c331d006359456cf6f8f953e37f2b9c7d568f3863f00bb5f7eb87fea4ac01b73
 F ext/fts3/tool/fts3view.c 413c346399159df81f86c4928b7c4a455caab73bfbc8cd68f950f632e5751674
@@ -93,8 +94,8 @@ F ext/fts5/fts5_buffer.c 3001fbabb585d6de52947b44b455235072b741038391f830d6b7292
 F ext/fts5/fts5_config.c 054359543566cbff1ba65a188330660a5457299513ac71c53b3a07d934c7b081
 F ext/fts5/fts5_expr.c bd3b81ce669c4104e34ffe66570af1999a317b142c15fccb112de9fb0caa57a6
 F ext/fts5/fts5_hash.c 65e7707bc8774706574346d18c20218facf87de3599b995963c3e6d6809f203d
-F ext/fts5/fts5_index.c b484322421cbb421d22bb2cd304001b80596d671cd626367c8c806b889de4b42
-F ext/fts5/fts5_main.c 7070031993ba5b5d89b13206ec4ef624895f2f7c0ec72725913d301e4d382445
+F ext/fts5/fts5_index.c bf9c3b2fc1cbc2b996693e393bb708756d770de2e931602102c2f0adbf75db2c
+F ext/fts5/fts5_main.c 8a16865b1652667c5a80592a4860a8fd40de283869d28da347a671c1c441933f
 F ext/fts5/fts5_storage.c 3c9b41fce41b6410f2e8f82eb035c6a29b2560483f773e6dc98cf3cb2e4ddbb5
 F ext/fts5/fts5_tcl.c b1445cbe69908c411df8084a10b2485500ac70a9c747cdc8cda175a3da59d8ae
 F ext/fts5/fts5_test_mi.c 08c11ec968148d4cb4119d96d819f8c1f329812c568bac3684f5464be177d3ee
@@ -178,7 +179,7 @@ F ext/fts5/test/fts5limits.test 8ab67cf5d311c124b6ceb0062d0297767176df4572d955fc
 F ext/fts5/test/fts5matchinfo.test 10c9a6f7fe61fb132299c4183c012770b10c4d5c2f2edb6df0b6607f683d737a
 F ext/fts5/test/fts5merge.test e92a8db28b45931e7a9c7b1bbd36101692759d00274df74d83fd29d25d53b3a6
 F ext/fts5/test/fts5merge2.test 3ebad1a59d6ad3fb66eff6523a09e95dc6367cbefb3cd73196801dea0425c8e2
-F ext/fts5/test/fts5misc.test 416ec0ffbc79320a0760ec32d6684866e3ccd3fbce09f9bcd62d9aee4c666b43
+F ext/fts5/test/fts5misc.test 3947a481486156536f417a015343f05f9f367a17f282a4e02bdb95bb5bd43293
 F ext/fts5/test/fts5multi.test a15bc91cdb717492e6e1b66fec1c356cb57386b980c7ba5af1915f97fe878581
 F ext/fts5/test/fts5multiclient.test 5ff811c028d6108045ffef737f1e9f05028af2458e456c0937c1d1b8dea56d45
 F ext/fts5/test/fts5near.test 211477940142d733ac04fad97cb24095513ab2507073a99c2765c3ddd2ef58bd
@@ -192,12 +193,12 @@ F ext/fts5/test/fts5porter2.test 0d251a673f02fa13ca7f011654873b3add20745f7402f10
 F ext/fts5/test/fts5prefix.test a0fa67b06650f2deaa7bf27745899d94e0fb547ad9ecbd08bfad98c04912c056
 F ext/fts5/test/fts5prefix2.test 3847ce46f70b82d61c6095103a9d7c53f2952c40a4704157bc079c04d9c8b18b
 F ext/fts5/test/fts5query.test ac363b17a442620bb0780e93c24f16a5f963dfe2f23dc85647b869efcfada728
-F ext/fts5/test/fts5rank.test c9fd4a1e36b4fa92d572ec13d846469b97da249d1c2f7fd3ee7e017ce46f2416
+F ext/fts5/test/fts5rank.test 30f29e278cd7fb8831ba4f082feb74d8eb90c463bf07113ae200afc2b467ef32
 F ext/fts5/test/fts5rebuild.test 55d6f17715cddbf825680dd6551efbc72ed916d8cf1cde40a46fc5d785b451e7
 F ext/fts5/test/fts5restart.test 835ecc8f449e3919f72509ab58056d0cedca40d1fe04108ccf8ac4c2ba41f415
 F ext/fts5/test/fts5rowid.test b8790ec170a8dc1942a15aef3db926a5f3061b1ff171013003d8297203a20ad6
 F ext/fts5/test/fts5savepoint.test fc02929f238d02a22df4172625704e029f7c1e0e92e332d654375690f8e6e43f
-F ext/fts5/test/fts5secure.test 214a561519d1b1817f146efd1057e2a97cc896e75c2accc77157d874154bda64
+F ext/fts5/test/fts5secure.test 833f987e6902a9ab20fabbaa7ca0662c6187fa368cbc7a8082fdf2bf22ee0304
 F ext/fts5/test/fts5secure2.test 2e961d7eef939f294c56b5d895cac7f1c3a60b934ee2cfd5e5e620bdf1ba6bbc
 F ext/fts5/test/fts5secure3.test c7e1080a6912f2a3ac68f2e05b88b72a99de38543509b2bbf427cac5c9c1c610
 F ext/fts5/test/fts5secure4.test 0d10a80590c07891478700af7793b232962042677432b9846cf7fc8337b67c97
@@ -522,17 +523,17 @@ F ext/session/sessionrowid.test 85187c2f1b38861a5844868126f69f9ec62223a03449a98a
 F ext/session/sessionsize.test 8fcf4685993c3dbaa46a24183940ab9f5aa9ed0d23e5fb63bfffbdb56134b795
 F ext/session/sessionstat1.test b039e38e2ba83767b464baf39b297cc0b1cc6f3292255cb467ea7e12d0d0280c
 F ext/session/sessionwor.test 6fd9a2256442cebde5b2284936ae9e0d54bde692d0f5fd009ecef8511f4cf3fc
-F ext/session/sqlite3session.c 1971b61ca45babf0d9e4bb669a65b0903135e9828af2fcd4f0c8f1b7acf36b6f
+F ext/session/sqlite3session.c 0fe9107318140cefa1b50f2e1e0f330ab359022599e5976820db349f33efae11
 F ext/session/sqlite3session.h 653e9d49c4edae231df8a4c8d69c2145195aedb32462d4b44229dbee7d2680fb
 F ext/session/test_session.c 5285482f83cd92b4c1fe12fcf88210566a18312f4f2aa110f6399dae46aeccbb
 F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
 F ext/userauth/user-auth.txt e6641021a9210364665fe625d067617d03f27b04
 F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865f002fc80cb
-F ext/wasm/EXPORTED_FUNCTIONS.fiddle.in 27450c8b8c70875a260aca55435ec927068b34cef801a96205adb81bdcefc65c
-F ext/wasm/GNUmakefile d02f3c8798b754f68b1f6b422ccff894a10bf352fc9c4eb8945baeace1acac28
+F ext/wasm/EXPORTED_FUNCTIONS.fiddle 7fb73f7150ab79d83bb45a67d257553c905c78cd3d693101699243f36c5ae6c3
+F ext/wasm/GNUmakefile 7eea788d3cde04135da82451a0afcd22f264157544ba69464a9285319a44b41d
 F ext/wasm/README-dist.txt 6382cb9548076fca472fb3330bbdba3a55c1ea0b180ff9253f084f07ff383576
 F ext/wasm/README.md a8a2962c3aebdf8d2104a9102e336c5554e78fc6072746e5daf9c61514e7d193
-F ext/wasm/api/EXPORTED_FUNCTIONS.sqlite3-api d6a5078f48a5301ed17b9a30331075d9b2506e1360c1f0dee0c7816c10acd9ab
+F ext/wasm/api/EXPORTED_FUNCTIONS.sqlite3-api c5eaceabb9e759aaae7d3101a4a3e542f96ab2c99d89a80ce20ec18c23115f33
 F ext/wasm/api/EXPORTED_FUNCTIONS.sqlite3-see fb29e62082a658f0d81102488414d422c393c4b20cc2f685b216bc566237957b
 F ext/wasm/api/EXPORTED_RUNTIME_METHODS.sqlite3-api 1ec3c73e7d66e95529c3c64ac3de2470b0e9e7fbf7a5b41261c367cf4f1b7287
 F ext/wasm/api/README.md 5eb44fa02e9c693a1884a3692428647894b0380b24bca120866b7a24c8786134
@@ -542,17 +543,17 @@ F ext/wasm/api/post-js-footer.js cd0a8ec768501d9bd45d325ab0442037fb0e33d1f3b4f08
 F ext/wasm/api/post-js-header.js 47b6b281f39ad59fa6e8b658308cd98ea292c286a68407b35ff3ed9cfd281a62
 F ext/wasm/api/pre-js.c-pp.js ad906703f7429590f2fbf5e6498513bf727a1a4f0ebfa057afb08161d7511219
 F ext/wasm/api/sqlite3-api-cleanup.js d235ad237df6954145404305040991c72ef8b1881715d2a650dda7b3c2576d0e
-F ext/wasm/api/sqlite3-api-glue.js b65e546568f1dfb35205b9792feb5146a6323d71b55cda58e2ed30def6dd52f3
+F ext/wasm/api/sqlite3-api-glue.js 26aedfb27915f4f316f6eac84078443e4f0d2dfe5f012310014923ed4b77b2b6
 F ext/wasm/api/sqlite3-api-oo1.js 9678dc4d9a5d39632b6ffe6ea94a023119260815bf32f265bf5f6c36c9516db8
 F ext/wasm/api/sqlite3-api-prologue.js 5f283b096b98bfb1ee2f2201e7ff0489dff00e29e1030c30953bdb4f5b87f4bd
 F ext/wasm/api/sqlite3-api-worker1.js 9f32af64df1a031071912eea7a201557fe39b1738645c0134562bb84e88e2fec
 F ext/wasm/api/sqlite3-license-version-header.js 0c807a421f0187e778dc1078f10d2994b915123c1223fe752b60afdcd1263f89
 F ext/wasm/api/sqlite3-opfs-async-proxy.js 8cf8a897726f14071fae6be6648125162b256dfb4f96555b865dbb7a6b65e379
 F ext/wasm/api/sqlite3-v-helper.js 7daa0eab0a513a25b05e9abae7b5beaaa39209b3ed12f86aeae9ef8d2719ed25
-F ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js abb69b5e008961026bf5ff433d7116cb046359af92a5daf73208af2e7ac80ae7
-F ext/wasm/api/sqlite3-vfs-opfs.c-pp.js e04fc2fda6a0200ef80efdbb4ddfa0254453558adb17ec3a230f93d2bf1d711c
+F ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js c7caf5ccd85d6e92bee4285871d51bc0e3e635b3e2d76f50515f5482a0ec0239
+F ext/wasm/api/sqlite3-vfs-opfs.c-pp.js cf0a2a182d16e71c5ccb1a870bfdba0d0da5e2fe5542907b036e92b3db5982c3
 F ext/wasm/api/sqlite3-wasm.c d4d4c2b349b43b7b861e6d2994299630fb79e07573ea6b61e28e8071b7d16b61
-F ext/wasm/api/sqlite3-worker1-promiser.c-pp.js bc06df0d599e625bde6a10a394e326dc68da9ff07fa5404354580f81566e591f
+F ext/wasm/api/sqlite3-worker1-promiser.c-pp.js c5ac33e39f21a3481812d7333ca6e18853640d423a01960ca8dbc6e7c5c3c21c
 F ext/wasm/api/sqlite3-worker1.c-pp.js da509469755035e919c015deea41b4514b5e84c12a1332e6cc8d42cb2cc1fb75
 F ext/wasm/batch-runner.html 4deeed44fe41496dc6898d9fb17938ea3291f40f4bfb977e29d0cef96fbbe4c8
 F ext/wasm/batch-runner.js 0dad6a02ad796f1003d3b7048947d275c4d6277f63767b8e685c27df8fdac93e
@@ -575,8 +576,8 @@ F ext/wasm/example_extra_init.c 2347cd69d19d839ef4e5e77b7855103a7fe3ef2af86f2e8c
 F ext/wasm/fiddle.make fa2ba6e90457ba2a71cb745f200d409caf773076df75ae5b177cc225d7627a11
 F ext/wasm/fiddle/emscripten.css 3d253a6fdb8983a2ac983855bfbdd4b6fa1ff267c28d69513dd6ef1f289ada3f
 F ext/wasm/fiddle/fiddle-worker.js e0153f9af6500805c6f09c0b3cfdb7d857e9d6863dbee9d50d1628fccf5f4b4d
+F ext/wasm/fiddle/fiddle.html 550c5aafce40bd218de9bf26192749f69f9b10bc379423ecd2e162bcef885c08
 F ext/wasm/fiddle/fiddle.js 974b995119ac443685d7d94d3b3c58c6a36540e9eb3fed7069d5653284071715
-F ext/wasm/fiddle/index.html 5daf54e8f3d7777cbb1ca4f93affe28858dbfff25841cb4ab81d694efed28ec2
 F ext/wasm/index-dist.html 22379774f0ad4edcaaa8cf9c674c82e794cc557719a8addabed74eb8069d412e
 F ext/wasm/index.html 4e7847b909f4ae0da8c829b150b79454050e53b3658431f138636257729cd42b
 F ext/wasm/jaccwabyt/jaccwabyt.js 1264710db3cfbcb6887d95665b7aeba60c1126eaef789ca4cf1a4a17d5bc7f54
@@ -604,7 +605,7 @@ F ext/wasm/wasmfs.make 8a4955882aaa0783b3f60a9484a1f0f3d8b6f775c0fcd17c082f31966
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 5ade0bc977aa135e79e3faaea894d5671b26107cc91e70783aa7dc83f22f3ba0
-F main.mk e18c03071dbb9da424212ba2a1ea331ae0e8f6d7d51283b7ad610c52ea11229c
+F main.mk 511bcec3cab5099d4c3a5525f7b65a1feba4153774749d73cca577ef211e1276
 F mptest/config01.test 3c6adcbc50b991866855f1977ff172eb6d901271
 F mptest/config02.test 4415dfe36c48785f751e16e32c20b077c28ae504
 F mptest/crash01.test 61e61469e257df0850df4293d7d4d6c2af301421
@@ -616,20 +617,20 @@ F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 acdff36db796e2d00225b911d3047d580cd136547298435426ce9d40347973cc
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F sqlite_cfg.h.in baf2e409c63d4e7a765e17769b6ff17c5a82bbd9cbf1e284fd2e4cefaff3fcf2
-F src/alter.c 3ff8c2fca0c0636d43459154bb40d79c882df1b34df77f89c4ec47ab2e2389f5
-F src/analyze.c d4cc28738c29e009640ec20ebb6936ba6fcefff0d11aa93398d9bb9a5ead6c1f
-F src/attach.c cc9d00d30da916ff656038211410ccf04ed784b7564639b9b61d1839ed69fd39
+F src/alter.c ed1b2b451fa483e536f623d1a533b9b395ed9e6c55d7dec00a0864d5698aa876
+F src/analyze.c caf60d36dd2be963a2a85bac3c0555ae97a8b295dd66c1e95ac868b69400c92b
+F src/attach.c 2af98700f1a3867a78475aa164571a2fbacce09c681076b01b119ef31b8ef4ac
 F src/auth.c 19b7ccacae3dfba23fc6f1d0af68134fa216e9040e53b0681b4715445ea030b4
 F src/backup.c 5c97e8023aab1ce14a42387eb3ae00ba5a0644569e3476f38661fa6f824c3523
 F src/bitvec.c 9eac5f42c11914d5ef00a75605bb205e934f435c579687f985f1f8b0995c8645
 F src/btmutex.c 79a43670447eacc651519a429f6ece9fd638563cf95b469d6891185ddae2b522
-F src/btree.c 7a37bdf09f338561880860681cb03499a60c3bb0869e539c58bc1d2cdd705ff2
+F src/btree.c 15611f72bd65aef23b3ae4026164f86e2466791be5b9745f8421d0eed3c5238a
 F src/btree.h 03e3356f5208bcab8eed4e094240fdac4a7f9f5ddf5e91045ce589f67d47c240
 F src/btreeInt.h 91a9e0c41a0e71fa91a742ec285c63dd8dcb38b73d14fae0ed7209174ff0fdc1
-F src/build.c a8ae3b32d9aa9bbd2c0e97d7c0dd80def9fbca408425de1608f57ee6f47f45f4
-F src/callback.c db3a45e376deff6a16c0058163fe0ae2b73a2945f3f408ca32cf74960b28d490
+F src/build.c 9b97abdac57ad46e42e7a65406ba4aed5838cfd885770f6d6c4ae4f038c901e1
+F src/callback.c fbd4e8247f1a7f37aec721bde0e312e79cc3bfa41f55a59930bc876ca6baf455
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
-F src/ctime.c cff2b493de894383832347c3a3f936a05f4e089a92b42366838da1735f3848b5
+F src/ctime.c 1cf5701f34089ae3d73c6863d27b644d105a70976939ccdc1ea9beda9aaa6b32
 F src/date.c f73f203b3877cef866c60ab402aec2bf89597219b60635cf50cbe3c5e4533e94
 F src/dbpage.c f3eea5f7ec47e09ee7da40f42b25092ecbe961fc59566b8e5f705f34335b2387
 F src/dbstat.c ec92074baa61d883de58c945162d9e666c13cd7cf3a23bc38b4d1c4d0b2c2bef
@@ -637,17 +638,17 @@ F src/delete.c cb766727c78e715f9fb7ec8a7d03658ed2a3016343ca687acfcec9083cdca500
 F src/expr.c 1affe0cc049683ef0ef3545d9b6901508556b0ef7e2892a344c3df6d7288d79d
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c a7fcbf7e66d14dbb73cf49f31489ebf66d0e6006c62b95246924a3bae9f37b36
-F src/func.c dd1ecd1be6aaa67c9fa723f841e05e1536314c6aaa0509e25289b310f64dbb9c
+F src/func.c 3c8e02958a3d4272659fcb234133b7572794ece60571779e88dd96ec16bae0d6
 F src/global.c 29f56a330ed9d1b5cd9b79ac0ca36f97ac3afc730ff8bfa987b0db9e559d684d
 F src/hash.c 9ee4269fb1d6632a6fecfb9479c93a1f29271bddbbaf215dd60420bcb80c7220
 F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
 F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
-F src/json.c ae840f87b418f039f5d336b488933d09396bd31e6b31e855b93055ccaee4e255
+F src/json.c 5c25f82e1c0f3eb44fb9a23feff6b7b952fd40122d9e3ab601a84ea83710a980
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 98cfba10989b3da6f1807ad42444017742db7f100a54f1032af7a8b1295912c0
-F src/main.c fde8f13c876a658b4e8b74b77d875ca887915c174ea6a2f3122d80966f93d865
+F src/main.c 05d0d3c48326d07f17195035a847fd26ef9386932fda0b17ee91b52b4245170f
 F src/malloc.c 47b82c5daad557d9b963e3873e99c22570fb470719082c6658bf64e3012f7d23
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 3bb59158c38e05f6270e761a9f435bf19827a264c13d1631c58b84bdc96d73b2
@@ -677,23 +678,23 @@ F src/parse.y aeb7760d41cfa86465e3adba506500c021597049fd55f82a30e5b7045862c28c
 F src/pcache.c 040b165f30622a21b7a9a77c6f2e4877a32fb7f22d4c7f0d2a6fa6833a156a75
 F src/pcache.h 1497ce1b823cf00094bb0cf3bac37b345937e6f910890c626b16512316d3abf5
 F src/pcache1.c 602acb23c471bb8d557a6f0083cc2be641d6cafcafa19e481eba7ef4c9ca0f00
-F src/pragma.c 37b8fb02d090262280c86e1e2654bf59d8dbfbfe8dc6733f2b968a11374c095a
-F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
-F src/prepare.c 80548297dc0e1fb3139cdebffb5a1bcac3dfac66d791012dd74838e70445072d
+F src/pragma.c 5a36e02eddeb60c836bd458fc72b72cd261b1f310690d58e10efd3439cd927d5
+F src/pragma.h 50f6d3b408ed56bde4f4e4aead8c0b2022030b692e8de237c1b7a0b5ce87a0c8
+F src/prepare.c 72ac47a9b9964ecade1a76b2b63c52f0078bf6b6e83c14b397be550d3082a1b7
 F src/printf.c e3ba080e2f409f9bfcc8d34724e6fc160e9c718dc92d0548f6b71b8b6f860ce2
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c 37953a5f36c60bea413c3c04efcd433b6177009f508ef2ace0494728912fe2e9
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 5f545a2c8702d4d3430bbb188cfec47d6c122d899061ef00cbe56af14591c574
-F src/shell.c.in 2f9be25294b68b07e7e81f0adcec4475aba6011b64f160e414efe226910c4d7b
-F src/sqlite.h.in 73a366c1c45d5ac9888cfe81c458826a44498531d106cfb4f328193ab5f6f17d
+F src/select.c e9fb48546ab1882639a3a960383f6342dddb776c0227615f8e19de51f0102f68
+F src/shell.c.in 7b8ea265d114c1c4c16c5e12fad12624354e3c7e6cce26fd05df7cd5f2a0d908
+F src/sqlite.h.in e749ae7dceb44608ecff703885e87b56e12e292962c4dd4d8e6ab924f7efe0ab
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 2f30b2671f4c03cd27a43f039e11251391066c97d11385f5f963bb40b03038ac
-F src/sqliteInt.h 025ed58a41968ef80d64cdc194caa8dd207b0256b147253d762fdac7a62408f9
+F src/sqliteInt.h e3189cb39d81d73296d4fcf484d43daa66894131e9e397da93b6f0bab66829a9
 F src/sqliteLimit.h 33b1c9baba578d34efe7dfdb43193b366111cdf41476b1e82699e14c11ee1fb6
-F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
+F src/status.c 501433a8bdf64be125746a53bb9180761f9364428b59b318365eb88afd6d5cea
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
-F src/tclsqlite.c ecbc3c99c0d0c3ed122a913f143026c26d38d57f33e06bb71185dd5c1efe37cd
+F src/tclsqlite.c df375d63a3b0f06e79f29b6876c228c8896599497d6f54adbcd12d7d71b3162d
 F src/test1.c ebba2473874a23add4a10881b90bd445cfa7f59f90749434938aec14239c6486
 F src/test2.c 54520d0565ef2b9bf0f8f1dcac43dc4d06baf4ffe13d10905f8d8c3ad3e4b9ab
 F src/test3.c e5178558c41ff53236ae0271e9acb3d6885a94981d2eb939536ee6474598840e
@@ -708,7 +709,7 @@ F src/test_backup.c bf5da90c9926df0a4b941f2d92825a01bbe090a0
 F src/test_bestindex.c 68c62586d2ae9f032903fe53be743657d0c2aac0a850b880938b668e1161d516
 F src/test_blob.c ae4a0620b478548afb67963095a7417cd06a4ec0a56adb453542203bfdcb31ce
 F src/test_btree.c 8b2dc8b8848cf3a4db93f11578f075e82252a274
-F src/test_config.c f0cc1f517deaa96dd384822ae2bb91534fa56aa458528b439830d709941d3932
+F src/test_config.c f8353821fbdc038bd080b5b125be365001ed3d9027d6410d0e40b4842e721778
 F src/test_delete.c e2fe07646dff6300b48d49b2fee2fe192ed389e834dd635e3b3bac0ce0bf9f8f
 F src/test_demovfs.c 38a459d1c78fd9afa770445b224c485e079018d6ac07332ff9bd07b54d2b8ce9
 F src/test_devsym.c 649434ed34d0b03fbd5a6b42df80f0f9a7e53f94dd1710aad5dd8831e91c4e86
@@ -732,10 +733,11 @@ F src/test_quota.c ea44c05f29b995bdb71c55eb0c602604884e55681d59b7736e604bbcc68b0
 F src/test_quota.h 2a8ad1952d1d2ca9af0ce0465e56e6c023b5e15d
 F src/test_rtree.c 671f3fae50ff116ef2e32a3bf1fe21b5615b4b7b
 F src/test_schema.c f5d6067dfc2f2845c4dd56df63e66ee826fb23877855c785f75cc2ca83fd0c1b
+F src/test_schemapool.c ae21a79f9bc7e9099ae78dbd46d5c28ee75330e62e3256a9fde25564ff9df492
 F src/test_sqllog.c 540feaea7280cd5f926168aee9deb1065ae136d0bbbe7361e2ef3541783e187a
 F src/test_superlock.c 4839644b9201da822f181c5bc406c0b2385f672e
 F src/test_syscall.c 9fdb13b1df05e639808d44fcb8f6064aaded32b6565c00b215cfd05a060d1aca
-F src/test_tclsh.c 3ff5d188a72f00807425954ea3b493dfd3a4b890ecc6700ea83bad2fd1332ecf
+F src/test_tclsh.c 15c29f9eb00907b361c2c3b11d0897256c8eeef3bdc5f1f169db044ab96b18e7
 F src/test_tclvar.c 33ff42149494a39c5fbb0df3d25d6fafb2f668888e41c0688d07273dcb268dfc
 F src/test_thread.c 7ddcf0c8b79fa3c1d172f82f322302c963d923cdb503c6171f3c8081586d0b01
 F src/test_vdbecov.c f60c6f135ec42c0de013a1d5136777aa328a776d33277f92abac648930453d43
@@ -748,28 +750,28 @@ F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
 F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
 F src/tokenize.c 23d9f4539880b40226254ad9072f4ecf12eb1902e62aea47aac29928afafcfd5
 F src/treeview.c 1d52fbc4e97161e65858d36e3424ea6e3fc045dd8a679c82b4b9593dc30de3bd
-F src/trigger.c ad6ab9452715fa9a8075442e15196022275b414b9141b566af8cdb7a1605f2b0
+F src/trigger.c 31ec6667245182684d7d9c6e2636759e7366a5a28546d8269982b8e490beb5c0
 F src/update.c 6904814dd62a7a93bbb86d9f1419c7f134a9119582645854ab02b36b676d9f92
 F src/upsert.c fa125a8d3410ce9a97b02cb50f7ae68a2476c405c76aa692d3acf6b8586e9242
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
-F src/util.c 278b81c3b33db1b5a5f3859adf8905c165b910080043061d44d3c5a25b4b406d
-F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
-F src/vdbe.c 346d848a0bf8128e3e3722c5406f4bde6c32d7093b93402c6f8e0718d19305c3
-F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
+F src/util.c 79f084901f52d9d7025200a177f7d1d66f83a73333fe486a2626490eaa49bc4c
+F src/vacuum.c 5bc892883611a65ca75b4129bcf5cf8b0908564b357373fdeee364d3b1af7cd7
+F src/vdbe.c 3ef6fd63dd5d7cd2eb1370c6e302174048d42fbaaa5ee27967b76debcd2d4673
+F src/vdbe.h 68fcbf7e5e8dd2094bc712fe4198216657272c978a7e93dbdb7e6ff5791c634c
 F src/vdbeInt.h 949669dfd8a41550d27dcb905b494f2ccde9a2e6c1b0b04daa1227e2e74c2b2c
 F src/vdbeapi.c 37341acd781fda162e8cf4d9fc2eaea2febad3b365877a9d7233b8c6d0960d85
-F src/vdbeaux.c e3aa5c46827cd95e0fc4d0f302fa3e901ab5f07258fdbb42709eeef40f63018d
-F src/vdbeblob.c 2516697b3ee8154eb8915f29466fb5d4f1ae39ee8b755ea909cefaf57ec5e2ce
+F src/vdbeaux.c 4dabe4beb01b71186438a4c994b57086b2594a49e19613d3b86d9362e5e496e7
+F src/vdbeblob.c a82465872ab124416bd55c4485f4a267472ad990b0aa08cc55035d26785dbbbe
 F src/vdbemem.c 317b9f48708139db6239ade40c7980b4bc8233168383690d588dad6d8437f722
 F src/vdbesort.c 0d40dca073c94e158ead752ef4225f4fee22dee84145e8c00ca2309afb489015
 F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1945f1d2e6be5927ec12c06d89b03ef2a4def34bf823
 F src/vdbevtab.c 57fa8f56478e5b5cb558cb425e7878515e0a105c54f96f1d1bbf4b9433529254
-F src/vtab.c 1ecf8c3745d29275688d583e12822fa984d421e0286b5ef50c137bc3bf6d7a64
+F src/vtab.c ea48d5fd38539a3be287c51d763b8e7df9d6c27e548518bb4b919cbb48a8a8e6
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 01e051a1e713d9eabdb25df38602837cec8f4c2cae448ce2cf6accc87af903e9
 F src/wal.h ba252daaa94f889f4b2c17c027e823d9be47ce39da1d3799886bbd51f0490452
 F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
-F src/where.c b8917792f1e0dbfa28fb29e6cd3d560060d69667be0ba4c491cbc772363264f5
+F src/where.c 54f0f2dd13109df383b9e42c0b61d8a24cf9287db244211e8cc50aefa640df1e
 F src/whereInt.h c7d19902863beadec1d04e66aca39c0bcd60b74f05f0eaa7422c7005dfc5d51a
 F src/wherecode.c 5d77db30a2a3dd532492ae882de114edba2fae672622056b1c7fd61f5917a8f1
 F src/whereexpr.c dc5096eca5ed503999be3bdee8a90c51361289a678d396a220912e9cb73b3c00
@@ -1156,7 +1158,7 @@ F test/fts4umlaut.test fcaca4471de7e78c9d1f7e8976e3e8704d7d8ad979d57a739d00f3f75
 F test/fts4unicode.test 82a9c16b68ba2f358a856226bb2ee02f81583797bc4744061c54401bf1a0f4c9
 F test/fts4upfrom.test f25835162c989dffd5e2ef91ec24c4848cc9973093e2d492d1c7b32afac1b49d
 F test/full.test 6b3c8fb43c6beab6b95438c1675374b95fab245d
-F test/func.test 2acd982669b2c15ceccc046385b458e985f90c9ca58b14d0ef75eec79c32f45b
+F test/func.test cbcf086273529d4a99b7199086da637a99039d2cad81dd7d7c4c9e25258ae164
 F test/func2.test 772d66227e4e6684b86053302e2d74a2500e1e0f
 F test/func3.test 600a632c305a88f3946d38f9a51efe145c989b2e13bd2b2a488db47fe76bab6a
 F test/func4.test 2285fb5792d593fef442358763f0fd9de806eda47dbc7a5934df57ffdc484c31
@@ -1273,8 +1275,8 @@ F test/json/README.md 63e3e589e1df8fd3cc1588ba1faaff659214003f8b77a15af5c6452b35
 F test/json/json-generator.tcl dc0dd0f393800c98658fc4c47eaa6af29d4e17527380cd28656fb261bddc8a3f
 F test/json/json-q1.txt 65f9d1cdcc4cffa9823fb73ed936aae5658700cd001fde448f68bfb91c807307
 F test/json/json-speed-check.sh 8b7babf530faa58bd59d6d362cec8e9036a68c5457ff46f3b1f1511d21af6737 x
-F test/json101.test dc9d5a2a5b1fd1b54dbd71c538b17933cc98d84b4c1f821ead754933663dca55
-F test/json102.test 24f6f204f9cde45b971016691d0b92a9b4c58040d699e36d6b12cb165f9083ff
+F test/json101.test 4d78048b185ffb9ae37645fa6934d48fc182473ae0bae088a1e2f7ba483c3a71
+F test/json102.test 4c69694773a470f1fda34e5f4ba24920b35184fb66050b450fc2ef9ab5ad310b
 F test/json103.test 53df87f83a4e5fa0c0a56eb29ff6c94055c6eb919f33316d62161a8880112dbe
 F test/json104.test 1b844a70cddcfa2e4cd81a5db0657b2e61e7f00868310f24f56a9ba0114348c1
 F test/json105.test 11670a4387f4308ae0318cadcbd6a918ea7edcd19fbafde020720a073952675d
@@ -1445,6 +1447,13 @@ F test/resetdb.test 54c06f18bc832ac6d6319e5ab23d5c8dd49fdbeec7c696d791682a8006bd
 F test/resolver01.test f4022acafda7f4d40eca94dbf16bc5fc4ac30ceb
 F test/returning1.test db532cde29d6aebbc48c6ddc3149b30476f8e69ca7a2c4b53986c7635e6fd8ec
 F test/returningfault.test ae4c4b5e8745813287a359d9ccdb9d5c883c2e68afb18fb0767937d5de5692a4
+F test/reuse1.test faa2ce5ff566d936b8a10d9e22ba2ee66a54ce89fdcf8aef561df6b15b0ff3d3
+F test/reuse2.test 025d54dcbf5bb32a869ffde4884789af2ec4a302b7dc4550dfbd16e635a3dd65
+F test/reuse3.test fa1edd6a303bbb93aa076d6579fce9d2ee2d9e1a8f4d7b613ac20a76ba622eaa
+F test/reuse4.test adaad66253aea6cc748674328abe69b650c5c78b8676ed1162d3de09742519f9
+F test/reuse5.test bbe6cf7384ef90f134392edd93d626385ef0bf6f40eefc3d993535cd0861d83b
+F test/reuse6.test f4674f9967aee2a0b49c02832120b8b495291c0d87aae084c54e6c0cc18132fe
+F test/reusefault.test ef646a0fb51d50ddfb4b7cd872f88e7d36eaba64bde7797b3418c3774e1c8d14
 F test/rollback.test 06680159bc6746d0f26276e339e3ae2f951c64812468308838e0a3362d911eaa
 F test/rollback2.test 3f3a4e20401825017df7e7671e9f31b6de5fae5620c2b9b49917f52f8c160a8f
 F test/rollbackfault.test 0e646aeab8840c399cfbfa43daab46fd609cf04a
@@ -1501,7 +1510,7 @@ F test/selectD.test 6d1909b49970bf92f45ce657505befcef5fc7cbc13544e18103a316d3218
 F test/selectE.test a8730ca330fcf40ace158f134f4fe0eb00c7edbf
 F test/selectF.test 21c94e6438f76537b72532fa9fd4710cdd455fc3
 F test/selectG.test 089f7d3d7e6db91566f00b036cb353107a2cca6220eb1cb264085a836dae8840
-F test/selectH.test 88237ded5925adfb3f27fdafb5428c2ffc4d61e313bceb854e225ffc3ef0d206
+F test/selectH.test 0b54599f1917d99568c9b929df22ec6261ed7b6d2f02a46b5945ef81b7871aac
 F test/session.test 78fa2365e93d3663a6e933f86e7afc395adf18be
 F test/sessionfuzz-data1.db 1f8d5def831f19b1c74571037f0d53a588ea49a6c4ca2a028fc0c27ef896dbcb
 F test/sessionfuzz.c 5eef09af01eeff6f20250ae4c0112c2e576e4d2f2026cc9a49dc5be6886fa6ee
@@ -1594,7 +1603,7 @@ F test/tabfunc01.test 54f27eacd054aa528a8b6e3331192c484104f30aaee351ad035f2b39a0
 F test/table.test eb3463b7add9f16a5bb836badf118cf391b809d09fdccd1f79684600d07ec132
 F test/tableapi.test ecbcc29c4ab62c1912c3717c48ea5c5e59f7d64e4a91034e6148bd2b82f177f4
 F test/tableopts.test dba698ba97251017b7c80d738c198d39ab747930
-F test/tclsqlite.test ad0bbd92edabe64cc91d990a0748142fe5ab962d74ac71fa3bfa94d50d2f4c87
+F test/tclsqlite.test 350536a4233914aa437b6735e3e8e683e921a71ced8fa9fb5396057a04dbea33
 F test/tempdb.test 4cdaa23ddd8acb4d79cbb1b68ccdfd09b0537aaba909ca69a876157c2a2cbd08
 F test/tempdb2.test 353864e96fd3ae2f70773d0ffbf8b1fe48589b02c2ec05013b540879410c3440
 F test/tempfault.test 0c0d349c9a99bf5f374655742577f8712c647900
@@ -1602,9 +1611,9 @@ F test/temptable.test d2c9b87a54147161bcd1822e30c1d1cd891e5b30
 F test/temptable2.test 76821347810ecc88203e6ef0dd6897b6036ac788e9dd3e6b04fd4d1631311a16
 F test/temptable3.test d11a0974e52b347e45ee54ef1923c91ed91e4637
 F test/temptrigger.test 38f0ca479b1822d3117069e014daabcaacefffcc
-F test/tester.tcl 68454ef88508c196d19e8694daa27bff7107a91857799eaa12f417188ae53ede
+F test/tester.tcl 9454edbf4df07b8294d15fb9695e8c7dc0b91eb979c3e888e205e7f3cdaf373f
 F test/testrunner.tcl a9fee4df57276bc9e446961b160068c269da5902cc8ffc3e8852d77626b7594c
-F test/testrunner_data.tcl c448693eb6fdbadb78cb26f6253d4f335666f9836f988afa575de960b666b19f
+F test/testrunner_data.tcl 968cfee74688eb698b6917b7e53aba2993a1789430192d5efd27d2173c2e36c6
 F test/thread001.test a0985c117eab62c0c65526e9fa5d1360dd1cac5b03bde223902763274ce21899
 F test/thread002.test c24c83408e35ba5a952a3638b7ac03ccdf1ce4409289c54a050ac4c5f1de7502
 F test/thread003.test ee4c9efc3b86a6a2767516a37bd64251272560a7
@@ -1616,7 +1625,7 @@ F test/thread3.test 5f53b6a8e7391d8653116fd0bee4f9774efee4410e039990821de39c6b43
 F test/thread_common.tcl 334639cadcb9f912bf82aa73f49efd5282e6cadd
 F test/threadtest1.c 6029d9c5567db28e6dc908a0c63099c3ba6c383b
 F test/threadtest2.c a70a8e94bef23339d34226eb9521015ef99f4df8
-F test/threadtest3.c 655bff6c0895ec03f014126aa65e808fac9aae8c5a7a7da58a510cbe8b43b781
+F test/threadtest3.c 25cb92accb4fa6d53e708d6006ed2db7a7533ef7b838ef1306455c6fe57e978a
 F test/threadtest4.c c1e67136ceb6c7ec8184e56ac61db28f96bd2925
 F test/threadtest5.c 9b4d782c58d8915d7e955ff8051f3d03628bda0d33b82971ea8c0f2f2808c421
 F test/time-wordcount.sh 8e0b0f8109367827ad5d58f5cc849705731e4b90
@@ -1792,12 +1801,13 @@ F test/triggerF.test 5d76f0a8c428ff87a4d5ed52da06f6096a2c787a1e21b846111dfac4123
 F test/triggerG.test 2b816093c91ba73c733cfa8aedcc210ad819d72a98b1da30768a3c56505233e9
 F test/triggerupfrom.test d1f9e56090408115c522bee626cc33a2f3370f627a5e341d832589d72e3aa271
 F test/trustschema1.test d2996bb284859c99956ac706160eab9f086919da738d19bfef3ac431cce8fd47
-F test/tt3_checkpoint.c ac7ca661d739280c89d9c253897df64a59a49369bd1247207ac0f655b622579d
-F test/tt3_index.c 39eec10a35f57672225be4d182862152896dee4a
-F test/tt3_lookaside1.c 0377e202c3c2a50d688cb65ba203afeda6fafeb9
+F test/tt3_checkpoint.c 69214e2ce81bbbd3c1b82c31e103607fd2e6790818aef4792957fc9cc88d067e
+F test/tt3_index.c 95592839426dc85ce5a7a57b41be2cbf3c2ec3457b9cd841a06ed5877f712c7c
+F test/tt3_lookaside1.c 2ddd99bfffeef288f0786827ef68f912f6f47ce3d3184e62f05808d8e13b920e
+F test/tt3_reuseschema.c 4d52e141f89f009028d8ab0bd1f0697d0edffa94bafc1fff0f7ad4d9d9baa549
 F test/tt3_shared.c b37d22defc944a2ac4c91c927fd06c1d48cd51e2ce9d004fe868625bd2399f93
-F test/tt3_stress.c f9a769ca8b026ecc76ee93ca8c9700a5619f8e51c581107c4053ba6ac97f616f
-F test/tt3_vacuum.c 71b254cde1fc49d6c8c44efd54f4668f3e57d7b3a8f4601ade069f75a999ba39
+F test/tt3_stress.c 077e817ac1168443b075fedb44e92db84bb4dc5bd3b6fe1aba25c94ac280b231
+F test/tt3_vacuum.c 727bfda1299b18435eeba80dee8e6ff43462146d7c1e2096cc809f01db568391
 F test/types.test bf816ce73c7dfcfe26b700c19f97ef4050d194ff
 F test/types2.test 1aeb81976841a91eef292723649b5c4fe3bc3cac
 F test/types3.test 99e009491a54f4dc02c06bdbc0c5eea56ae3e25a
@@ -2012,7 +2022,7 @@ F tool/loadfts.c c3c64e4d5e90e8ba41159232c2189dba4be7b862
 F tool/logest.c c34e5944318415de513d29a6098df247a9618c96d83c38d4abd88641fe46e669
 F tool/max-limits.c cbb635fbb37ae4d05f240bfb5b5270bb63c54439
 F tool/merge-test.tcl de76b62f2de2a92d4c1ca4f976bce0aea6899e0229e250479b229b2a1914b176
-F tool/mkautoconfamal.sh f62353eb6c06ab264da027fd4507d09914433dbdcab9cb011cdc18016f1ab3b8
+F tool/mkautoconfamal.sh 7077151b62ecb2848c5b2d36cdbcd8caa0b58f2c12dcdac6e982da39d29d213c
 F tool/mkccode.tcl 86463e68ce9c15d3041610fedd285ce32a5cf7a58fc88b3202b8b76837650dbe x
 F tool/mkctimec.tcl aca4b83e49aecf10368cd5d11bc4847061041ade026db5bd8da17ef201f1403b x
 F tool/mkkeywordhash.c b9faa0ae7e14e4dbbcd951cddd786bf46b8a65bb07b129ba8c0cfade723aaffd
@@ -2020,7 +2030,7 @@ F tool/mkmsvcmin.tcl 8897d515ef7f94772322db95a3b6fce6c614d84fe0bdd06ba5a1c786351
 F tool/mkopcodec.tcl 33d20791e191df43209b77d37f0ff0904620b28465cca6990cf8d60da61a07ef
 F tool/mkopcodeh.tcl 769d9e6a8b462323150dc13a8539d6064664b72974f7894befe2491cc73e05cd
 F tool/mkopts.tcl 680f785fdb09729fd9ac50632413da4eadbdf9071535e3f26d03795828ab07fa
-F tool/mkpragmatab.tcl bd07bd59d45d0f3448e123d6937e9811195f9908a51e09d774609883055bfd3d
+F tool/mkpragmatab.tcl 0e059aaab521b490c86ba3d4f945319b438558de7738e90f26c54f4ffcdd79bb
 F tool/mkshellc.tcl b7adf08b82de60811d2cb6af05ff59fc17e5cd6f3e98743c14eaaa3f8971fed0
 F tool/mksourceid.c 36aa8020014aed0836fd13c51d6dc9219b0df1761d6b5f58ff5b616211b079b9
 F tool/mkspeedsql.tcl a1a334d288f7adfe6e996f2e712becf076745c97
@@ -2060,6 +2070,7 @@ F tool/sqltclsh.c.in 1bcc2e9da58fadf17b0bf6a50e68c1159e602ce057210b655d50bad5aaa
 F tool/sqltclsh.tcl 862f4cf1418df5e1315b5db3b5ebe88969e2a784525af5fbf9596592f14ed848
 F tool/src-verify.c 41c586dee84d0b190ad13e0282ed83d4a65ec9fefde9adf4943efdf6558eea7f
 F tool/srcck1.c 371de5363b70154012955544f86fdee8f6e5326f
+F tool/srctree-check.tcl cef630bc4ff21a460d72479c43a42bf1c1ed61897659305c35c8d72e91bcb176
 F tool/stack_usage.tcl f8e71b92cdb099a147dad572375595eae55eca43
 F tool/stripccomments.c 20b8aabc4694d0d4af5566e42da1f1a03aff057689370326e9269a9ddcffdc37
 F tool/symbols-mingw.sh 4dbcea7e74768305384c9fd2ed2b41bbf9f0414d
@@ -2092,11 +2103,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 3f5bec9a684f6b3d88383617831862fc5595a51ad99ec12430ac6650b704ccbb
-R 0c01ee5f49ac8bbf7d5b3e02bf525f93
-T +sym-major-release *
-T +sym-release *
-T +sym-version-3.43.0 *
+P d96586b51b591608f3dbae9a1dd201ce10f1f700b77d913487e6c269af42100d 4310099cce5a487035fa535dd3002c59ac7f1d1bec68d7cf317fd3e769484790
+R 69257dc7955d22966fa2e56db1cba65a
 U drh
-Z 2bd48930e1a5ff814b90ece6e1f4c0d0
+Z e3af5bef3c979f2047f2124e290983dd
 # Remove this line to create a well-formed Fossil manifest.
@@ -1 +1 @@
-0f80b798b3f4b81a7bb4233c58294edd0f1156f36b6ecf5ab8e83631d468778c
+5fefa147ca4703e883670f0d65f8ea32c64474f1ca6a0d50d691cc677b987b71
@@ -112,8 +112,8 @@ static void renameReloadSchema(Parse *pParse, int iDb, u16 p5){
  Vdbe *v = pParse->pVdbe;
  if( v ){
    sqlite3ChangeCookie(pParse, iDb);
-    sqlite3VdbeAddParseSchemaOp(pParse->pVdbe, iDb, 0, p5);
-    if( iDb!=1 ) sqlite3VdbeAddParseSchemaOp(pParse->pVdbe, 1, 0, p5);
+    sqlite3VdbeAddParseSchemaOp(pParse, iDb, 0, p5);
+    if( iDb!=1 ) sqlite3VdbeAddParseSchemaOp(pParse, 1, 0, p5);
  }
 }

@@ -212,6 +212,7 @@ static void openStatTable(
        ** side-effect of the CREATE TABLE statement is to leave the rootpage 
        ** of the new table in register pParse->regRoot. This is important 
        ** because the OpenWrite opcode below will be needing it. */
+        sqlite3SchemaWritable(pParse, iDb);
        sqlite3NestedParse(pParse,
            "CREATE TABLE %Q.%s(%s)", pDb->zDbSName, zTab, aTable[i].zCols
        );
@@ -218,14 +218,14 @@ static void attachFunc(
  ** way we found it.
  */
  if( rc==SQLITE_OK ){
-    sqlite3BtreeEnterAll(db);
    db->init.iDb = 0;
    db->mDbFlags &= ~(DBFLAG_SchemaKnownOk);
-    if( !REOPEN_AS_MEMDB(db) ){
+    if( !IsSharedSchema(db) && !REOPEN_AS_MEMDB(db) ){
+      sqlite3BtreeEnterAll(db);
      rc = sqlite3Init(db, &zErrDyn);
+      sqlite3BtreeLeaveAll(db);
+      assert( zErrDyn==0 || rc!=SQLITE_OK );
    }
-    sqlite3BtreeLeaveAll(db);
-    assert( zErrDyn==0 || rc!=SQLITE_OK );
  }
 #ifdef SQLITE_USER_AUTHENTICATION
  if( rc==SQLITE_OK && !REOPEN_AS_MEMDB(db) ){
@@ -325,6 +325,7 @@ static void detachFunc(
    pEntry = sqliteHashNext(pEntry);
  }

+  (void)sqlite3SchemaDisconnect(db, i, 0);
  sqlite3BtreeClose(pDb->pBt);
  pDb->pBt = 0;
  pDb->pSchema = 0;
@@ -354,7 +355,9 @@ static void codeAttach(
  sqlite3* db = pParse->db;
  int regArgs;

-  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ) goto attach_end;
+  if( (db->mDbFlags & DBFLAG_EncodingFixed)==0 ){
+    if( SQLITE_OK!=sqlite3ReadSchema(pParse) ) goto attach_end;
+  }

  if( pParse->nErr ) goto attach_end;
  memset(&sName, 0, sizeof(NameContext));
@@ -7493,6 +7493,7 @@ static int rebuildPage(
  int k;                          /* Current slot in pCArray->apEnd[] */
  u8 *pSrcEnd;                    /* Current pCArray->apEnd[k] value */

+  assert( nCell>0 );
  assert( i<iEnd );
  j = get2byte(&aData[hdr+5]);
  if( NEVER(j>(u32)usableSize) ){ j = 0; }
@@ -7799,6 +7800,7 @@ static int editPage(
  return SQLITE_OK;
 editpage_fail:
  /* Unable to edit this page. Rebuild it from scratch instead. */
+  if( nNew<1 ) return SQLITE_CORRUPT_BKPT;
  populateCellCache(pCArray, iNew, nNew);
  return rebuildPage(pCArray, iNew, nNew, pPg);
 }
@@ -343,6 +343,39 @@ int sqlite3UserAuthTable(const char *zTable){
 }
 #endif

+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+/*
+** If this database connection was opened with the SQLITE_OPEN_SHARED_SCHEMA
+** flag specified, then ensure that the database schema for database iDb
+** is loaded. Either by obtaining a Schema object from the schema-pool, or
+** by reading the contents of the sqlite_master table. Unless it is NULL, 
+** the location indicated by parameter pbUnload is set to 1 if a shared-schema 
+** is loaded.
+**
+** If the database handle was not opened with SQLITE_OPEN_SHARED_SCHEMA, or
+** if the schema for database iDb is already loaded, this function is a no-op.
+**
+** SQLITE_OK is returned if successful, or an SQLite error code otherwise. If
+** an error code is returned, (*pzErr) may be set to point to a buffer
+** containing an error message. It is the responsibility of the caller to
+** eventually free this buffer using sqlite3_free().
+*/
+int sqlite3SchemaLoad(sqlite3 *db, int iDb, int *pbUnload, char **pzErr){
+  int rc = SQLITE_OK;
+  if( IsSharedSchema(db) 
+      && DbHasProperty(db, iDb, DB_SchemaLoaded)==0 
+      && (db->init.busy==0 || (iDb!=1 && db->init.iDb==1))
+  ){
+    struct sqlite3InitInfo sv = db->init;
+    memset(&db->init, 0, sizeof(struct sqlite3InitInfo));
+    rc = sqlite3InitOne(db, iDb, pzErr, 0);
+    db->init = sv;
+    if( pbUnload && rc==SQLITE_OK && iDb!=1 ) *pbUnload = 1;
+  }
+  return rc;
+}
+#endif
+
 /*
 ** Locate the in-memory structure that describes a particular database
 ** table given the name of that table and (optionally) the name of the
@@ -368,59 +401,41 @@ Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){
    return 0;
  }
 #endif
-  if( zDatabase ){
-    for(i=0; i<db->nDb; i++){
-      if( sqlite3StrICmp(zDatabase, db->aDb[i].zDbSName)==0 ) break;
-    }
-    if( i>=db->nDb ){
-      /* No match against the official names.  But always match "main"
-      ** to schema 0 as a legacy fallback. */
-      if( sqlite3StrICmp(zDatabase,"main")==0 ){
-        i = 0;
-      }else{
-        return 0;
-      }
-    }
-    p = sqlite3HashFind(&db->aDb[i].pSchema->tblHash, zName);
-    if( p==0 && sqlite3StrNICmp(zName, "sqlite_", 7)==0 ){
-      if( i==1 ){
-        if( sqlite3StrICmp(zName+7, &PREFERRED_TEMP_SCHEMA_TABLE[7])==0
-         || sqlite3StrICmp(zName+7, &PREFERRED_SCHEMA_TABLE[7])==0
-         || sqlite3StrICmp(zName+7, &LEGACY_SCHEMA_TABLE[7])==0
-        ){
-          p = sqlite3HashFind(&db->aDb[1].pSchema->tblHash,
-                              LEGACY_TEMP_SCHEMA_TABLE);
+  while(1){
+    for(i=OMIT_TEMPDB; i<db->nDb; i++){
+      int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
+      if( zDatabase==0 || sqlite3DbIsNamed(db, j, zDatabase) ){
+        int bUnload = 0;
+        assert( sqlite3SchemaMutexHeld(db, j, 0) );
+        if( IsSharedSchema(db) ){
+          Parse *pParse = db->pParse;
+          if( pParse && pParse->nErr==0 ){
+            pParse->rc = sqlite3SchemaLoad(db, j, &bUnload, &pParse->zErrMsg);
+            if( pParse->rc ) pParse->nErr++;
+          }
        }
-      }else{
-        if( sqlite3StrICmp(zName+7, &PREFERRED_SCHEMA_TABLE[7])==0 ){
-          p = sqlite3HashFind(&db->aDb[i].pSchema->tblHash,
-                              LEGACY_SCHEMA_TABLE);
+        p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName);
+        if( p ) return p;
+        if( bUnload ){
+          sqlite3SchemaRelease(db, j);
        }
      }
    }
-  }else{
-    /* Match against TEMP first */
-    p = sqlite3HashFind(&db->aDb[1].pSchema->tblHash, zName);
-    if( p ) return p;
-    /* The main database is second */
-    p = sqlite3HashFind(&db->aDb[0].pSchema->tblHash, zName);
-    if( p ) return p;
-    /* Attached databases are in order of attachment */
-    for(i=2; i<db->nDb; i++){
-      assert( sqlite3SchemaMutexHeld(db, i, 0) );
-      p = sqlite3HashFind(&db->aDb[i].pSchema->tblHash, zName);
-      if( p ) break;
+    /* Not found.  If the name we were looking for was temp.sqlite_master
+    ** then change the name to sqlite_temp_master and try again. */
+    if( sqlite3StrICmp(zName, PREFERRED_SCHEMA_TABLE)==0 ){
+      zName = LEGACY_SCHEMA_TABLE;
+      continue;
    }
-    if( p==0 && sqlite3StrNICmp(zName, "sqlite_", 7)==0 ){
-      if( sqlite3StrICmp(zName+7, &PREFERRED_SCHEMA_TABLE[7])==0 ){
-        p = sqlite3HashFind(&db->aDb[0].pSchema->tblHash, LEGACY_SCHEMA_TABLE);
-      }else if( sqlite3StrICmp(zName+7, &PREFERRED_TEMP_SCHEMA_TABLE[7])==0 ){
-        p = sqlite3HashFind(&db->aDb[1].pSchema->tblHash,
-                            LEGACY_TEMP_SCHEMA_TABLE);
-      }
+    if( sqlite3StrICmp(zName, PREFERRED_TEMP_SCHEMA_TABLE)==0 ){
+      zName = LEGACY_TEMP_SCHEMA_TABLE;
+      continue;
    }
+    if( sqlite3StrICmp(zName, LEGACY_SCHEMA_TABLE)!=0 ) break;
+    if( sqlite3_stricmp(zDatabase, db->aDb[1].zDbSName)!=0 ) break;
+    zName = LEGACY_TEMP_SCHEMA_TABLE;
  }
-  return p;
+  return 0;
 }

 /*
@@ -445,6 +460,7 @@ Table *sqlite3LocateTable(
  /* Read the database schema. If an error occurs, leave an error message
  ** and code in pParse and return NULL. */
  if( (db->mDbFlags & DBFLAG_SchemaKnownOk)==0
+   && !IsSharedSchema(db)
   && SQLITE_OK!=sqlite3ReadSchema(pParse)
  ){
    return 0;
@@ -461,9 +477,21 @@ Table *sqlite3LocateTable(
      if( pMod==0 && sqlite3_strnicmp(zName, "pragma_", 7)==0 ){
        pMod = sqlite3PragmaVtabRegister(db, zName);
      }
-      if( pMod && sqlite3VtabEponymousTableInit(pParse, pMod) ){
-        testcase( pMod->pEpoTab==0 );
-        return pMod->pEpoTab;
+      if( pMod ){
+        if( IsSharedSchema(db) && pParse->nErr==0 ){
+          int bDummy = 0;
+          pParse->rc = sqlite3SchemaLoad(db, 0, &bDummy, &pParse->zErrMsg);
+          if( pParse->rc ) pParse->nErr++;
+          (void)bDummy;
+        }
+        if( sqlite3VtabEponymousTableInit(pParse, pMod) ){
+          Table *pEpoTab = pMod->pEpoTab;
+          if( pEpoTab ){
+            assert( IsSharedSchema(db)||pEpoTab->pSchema==db->aDb[0].pSchema );
+            pEpoTab->pSchema = db->aDb[0].pSchema;  /* For SHARED_SCHEMA mode */
+          }
+          return pEpoTab;
+        }
      }
    }
 #endif
@@ -473,15 +501,13 @@ Table *sqlite3LocateTable(
    p = 0;
  }

-  if( p==0 ){
+  if( p==0 && (!IsSharedSchema(db) || pParse->nErr==0) ){
    const char *zMsg = flags & LOCATE_VIEW ? "no such view" : "no such table";
    if( zDbase ){
      sqlite3ErrorMsg(pParse, "%s: %s.%s", zMsg, zDbase, zName);
    }else{
      sqlite3ErrorMsg(pParse, "%s: %s", zMsg, zName);
    }
-  }else{
-    assert( HasRowid(p) || p->iPKey<0 );
  }

  return p;
@@ -650,11 +676,10 @@ void sqlite3ResetOneSchema(sqlite3 *db, int iDb){
    DbSetProperty(db, 1, DB_ResetWanted);
    db->mDbFlags &= ~DBFLAG_SchemaKnownOk;
  }
-
  if( db->nSchemaLock==0 ){
    for(i=0; i<db->nDb; i++){
      if( DbHasProperty(db, i, DB_ResetWanted) ){
-        sqlite3SchemaClear(db->aDb[i].pSchema);
+        sqlite3SchemaClearOrDisconnect(db, i);
      }
    }
  }
@@ -667,16 +692,17 @@ void sqlite3ResetOneSchema(sqlite3 *db, int iDb){
 void sqlite3ResetAllSchemasOfConnection(sqlite3 *db){
  int i;
  sqlite3BtreeEnterAll(db);
-  for(i=0; i<db->nDb; i++){
+  for(i=0; i<db->nDb; i=(i?i+1:2)){
    Db *pDb = &db->aDb[i];
    if( pDb->pSchema ){
      if( db->nSchemaLock==0 ){
-        sqlite3SchemaClear(pDb->pSchema);
+        sqlite3SchemaClearOrDisconnect(db, i);
      }else{
        DbSetProperty(db, i, DB_ResetWanted);
      }
    }
  }
+  sqlite3SchemaClear(db->aDb[1].pSchema);
  db->mDbFlags &= ~(DBFLAG_SchemaChange|DBFLAG_SchemaKnownOk);
  sqlite3VtabUnlockList(db);
  sqlite3BtreeLeaveAll(db);
@@ -1284,7 +1310,7 @@ void sqlite3StartTable(
  */
  if( !IN_SPECIAL_PARSE ){
    char *zDb = db->aDb[iDb].zDbSName;
-    if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    if( !IsSharedSchema(db) && SQLITE_OK!=sqlite3ReadSchema(pParse) ){
      goto begin_table_error;
    }
    pTable = sqlite3FindTable(db, zName, zDb);
@@ -2923,7 +2949,7 @@ void sqlite3EndTable(
 #endif

    /* Reparse everything to update our internal data structures */
-    sqlite3VdbeAddParseSchemaOp(v, iDb,
+    sqlite3VdbeAddParseSchemaOp(pParse, iDb,
           sqlite3MPrintf(db, "tbl_name='%q' AND type!='trigger'", p->zName),0);
  }

@@ -3481,7 +3507,7 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
  }
  assert( pParse->nErr==0 );
  assert( pName->nSrc==1 );
-  if( sqlite3ReadSchema(pParse) ) goto exit_drop_table;
+  if( !IsSharedSchema(db) && sqlite3ReadSchema(pParse) ) goto exit_drop_table;
  if( noErr ) db->suppressErr++;
  assert( isView==0 || isView==LOCATE_VIEW );
  pTab = sqlite3LocateTableItem(pParse, isView, &pName->a[0]);
@@ -3496,6 +3522,7 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
  }
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  assert( iDb>=0 && iDb<db->nDb );
+  sqlite3SchemaWritable(pParse, iDb);

  /* If pTab is a virtual table, call ViewGetColumnNames() to ensure
  ** it is initialized.
@@ -3950,7 +3977,7 @@ void sqlite3CreateIndex(
  if( IN_DECLARE_VTAB && idxType!=SQLITE_IDXTYPE_PRIMARYKEY ){
    goto exit_create_index;
  }
-  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+  if( !IsSharedSchema(db) && SQLITE_OK!=sqlite3ReadSchema(pParse) ){
    goto exit_create_index;
  }
  if( sqlite3HasExplicitNulls(pParse, pList) ){
@@ -4450,7 +4477,7 @@ void sqlite3CreateIndex(
      if( pTblName ){
        sqlite3RefillIndex(pParse, pIndex, iMem);
        sqlite3ChangeCookie(pParse, iDb);
-        sqlite3VdbeAddParseSchemaOp(v, iDb,
+        sqlite3VdbeAddParseSchemaOp(pParse, iDb,
            sqlite3MPrintf(db, "name='%q' AND type='index'", pIndex->zName), 0);
        sqlite3VdbeAddOp2(v, OP_Expire, 0, 1);
      }
@@ -4600,6 +4627,7 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
    goto exit_drop_index;
  }
  iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);
+  sqlite3SchemaWritable(pParse, iDb);
 #ifndef SQLITE_OMIT_AUTHORIZATION
  {
    int code = SQLITE_DROP_INDEX;
@@ -16,6 +16,63 @@

 #include "sqliteInt.h"

+/*
+** Connections opened with the SQLITE_OPEN_SHARED_SCHEMA flag specified
+** may use SchemaPool objects for any database that is not the temp db
+** (iDb==1). For such databases (type "struct Db") there are three states
+** the Schema/SchemaPool object may be in.
+**
+**   1) pSPool==0, pSchema points to an empty object allocated by
+**      sqlite3_malloc(). DB_SchemaLoaded flag is clear.
+**
+**   2) pSPool!=0, pSchema points to a populated object owned by the
+**      SchemaPool. DB_SchemaLoaded flag is set.
+**
+**   3) pSPool!=0, pSchema points to the SchemaPool's static object
+**      (SchemaPool.sSchema).
+*/
+struct SchemaPool {
+  int nRef;                       /* Number of pointers to this object */
+  int nDelete;                    /* Schema objects deleted by ReleaseAll() */
+  u64 cksum;                      /* Checksum for this Schema contents */
+  Schema *pSchema;                /* Linked list of Schema objects */
+  Schema sSchema;                 /* The single dummy schema object */
+  SchemaPool *pNext;              /* Next element in schemaPoolList */
+};
+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+#ifdef SQLITE_DEBUG
+static void assert_schema_state_ok(sqlite3 *db){
+  if( IsSharedSchema(db) && db->eOpenState!=SQLITE_STATE_ZOMBIE ){
+    int i;
+    for(i=0; i<db->nDb; i++){
+      if( i!=1 ){
+        Db *pDb = &db->aDb[i];
+        Btree *pBt = pDb->pBt;
+        if( pBt==0 ) continue;
+        assert( sqlite3BtreeSchema(pBt, 0, 0)==0 );
+        assert( pDb->pSchema );
+        if( pDb->pSPool ){
+          if( DbHasProperty(db, i, DB_SchemaLoaded)==0 ){
+            assert( pDb->pSchema->tblHash.count==0 );
+            assert( pDb->pSchema==&pDb->pSPool->sSchema );
+          }else{
+            assert( pDb->pSchema!=&pDb->pSPool->sSchema );
+          }
+        }else{
+          assert( DbHasProperty(db, i, DB_SchemaLoaded)==0 );
+          assert( pDb->pSchema->tblHash.count==0 );
+          assert( pDb->pSchema!=&pDb->pSPool->sSchema );
+        }
+      }
+    }
+  }
+}
+#else
+# define assert_schema_state_ok(x)
+#endif
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+
 /*
 ** Invoke the 'collation needed' callback to request a collation sequence
 ** in the encoding enc of name zName, length nName.
@@ -517,15 +574,317 @@ void sqlite3SchemaClear(void *p){
 }

 /*
-** Find and return the schema associated with a BTree.  Create
-** a new one if necessary.
+** If this database was opened with the SQLITE_OPEN_SHARED_SCHEMA flag
+** and iDb!=1, then disconnect from the schema-pool associated with
+** database iDb. Otherwise, clear the Schema object belonging to
+** database iDb. 
+**
+** If an OOM error occurs while disconnecting from a schema-pool, 
+** the db->mallocFailed flag is set.
+*/
+void sqlite3SchemaClearOrDisconnect(sqlite3 *db, int iDb){
+  Db *pDb = &db->aDb[iDb];
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  if( IsSharedSchema(db) && iDb!=1 && pDb->pSPool ){
+    sqlite3SchemaDisconnect(db, iDb, 1);
+  }else
+#endif
+  {
+    sqlite3SchemaClear(pDb->pSchema);
+  }
+}
+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+/*
+** Global linked list of SchemaPool objects. Read and write access must
+** be protected by the SQLITE_MUTEX_STATIC_MASTER mutex.
+*/
+static SchemaPool *SQLITE_WSD schemaPoolList = 0;
+
+#ifdef SQLITE_TEST
+/*
+** Return a pointer to the head of the linked list of SchemaPool objects.
+** This is used by the virtual table in file test_schemapool.c.
+*/
+SchemaPool *sqlite3SchemaPoolList(void){ return schemaPoolList; }
+#endif
+
+/*
+** Database handle db was opened with the SHARED_SCHEMA flag, and database
+** iDb is currently connected to a schema-pool. When this function is called,
+** (*pnByte) is set to nInit plus the amount of memory used to store a 
+** single instance of the Schema objects managed by the schema-pool.
+** This function adjusts (*pnByte) sot hat it is set to nInit plus
+** (nSchema/nRef) of the amount of memory used by a single Schema object,
+** where nSchema is the number of Schema objects allocated by this pool,
+** and nRef is the number of connections to the schema-pool.
+*/
+void sqlite3SchemaAdjustUsed(sqlite3 *db, int iDb, int nInit, int *pnByte){
+  SchemaPool *pSPool = db->aDb[iDb].pSPool;
+  int nSchema = 0;
+  Schema *p;
+  sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+  for(p=pSPool->pSchema; p; p=p->pNext){
+    nSchema++;
+  }
+  *pnByte = nInit + ((*pnByte - nInit) * nSchema) / pSPool->nRef;
+  sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+}
+
+/*
+** Check that the schema of db iDb is writable (either because it is the 
+** temp db schema or because the db handle was opened without
+** SQLITE_OPEN_SHARED_SCHEMA). If so, do nothing. Otherwise, leave an 
+** error in the Parse object.
+*/
+void sqlite3SchemaWritable(Parse *pParse, int iDb){
+  if( iDb!=1 && IsSharedSchema(pParse->db) && IN_DECLARE_VTAB==0 ){
+    sqlite3ErrorMsg(pParse, "attempt to modify read-only schema");
+  }
+}
+
+/*
+** The schema object passed as the only argument was allocated using
+** sqlite3_malloc() and then populated using the usual mechanism. This
+** function frees both the Schema object and its contents.
+*/
+static void schemaDelete(Schema *pSchema){
+  sqlite3SchemaClear((void*)pSchema);
+  sqlite3_free(pSchema);
+}
+
+/*
+** When this function is called, the database connection Db must be
+** using a schema-pool (Db.pSPool!=0) and must currently have Db.pSchema
+** set to point to a populated schema object checked out from the 
+** schema-pool. It is also assumed that the STATIC_MASTER mutex is held.
+** This function returns the Schema object to the schema-pool and sets
+** Db.pSchema to point to the schema-pool's static, empty, Schema object.
+*/
+static void schemaRelease(sqlite3 *db, Db *pDb){
+  Schema *pRelease = pDb->pSchema;
+  SchemaPool *pSPool = pDb->pSPool;
+
+  assert( pDb->pSchema->iGeneration==pSPool->sSchema.iGeneration );
+  pDb->pSchema = &pSPool->sSchema;
+
+  assert( pDb->pSPool && pRelease );
+  assert( pRelease->schemaFlags & DB_SchemaLoaded );
+  assert( (pDb->pSchema->schemaFlags & DB_SchemaLoaded)==0 );
+  assert( sqlite3_mutex_held(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER)) );
+
+  /* If the DBFLAG_FreeSchema flag is set and the database connection holds
+  ** at least one other copy of the schema being released, delete it instead
+  ** of returning it to the schema-pool.  */
+  if( db->mDbFlags & DBFLAG_FreeSchema ){
+    int i;
+    for(i=0; i<db->nDb; i++){
+      Db *p = &db->aDb[i];
+      if( p!=pDb && p->pSchema!=&pSPool->sSchema && pDb->pSPool==p->pSPool ){
+        pSPool->nDelete++;
+        schemaDelete(pRelease);
+        return;
+      }
+    }
+  }
+
+  pRelease->pNext = pDb->pSPool->pSchema;
+  pDb->pSPool->pSchema = pRelease;
+}
+
+/*
+** The schema for database iDb of database handle db, which was opened
+** with SQLITE_OPEN_SHARED_SCHEMA, has just been parsed. This function either
+** finds a matching SchemaPool object on the global list (schemaPoolList) or
+** else allocates a new one and sets the Db.pSPool variable accordingly.
+**
+** SQLITE_OK is returned if no error occurs, or an SQLite error code 
+** (SQLITE_NOMEM) otherwise.
+*/
+int sqlite3SchemaConnect(sqlite3 *db, int iDb, u64 cksum){
+  Schema *pSchema = db->aDb[iDb].pSchema;
+  SchemaPool *p;
+
+  assert( pSchema && iDb!=1 && db->aDb[iDb].pSPool==0 );
+
+  sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+
+  /* Search for a matching SchemaPool object */
+  for(p=schemaPoolList; p; p=p->pNext){
+    if( p->cksum==cksum && p->sSchema.schema_cookie==pSchema->schema_cookie ){
+      break;
+    }
+  }
+  if( !p ){
+    /* No SchemaPool object found. Allocate a new one. */
+    p = (SchemaPool*)sqlite3_malloc(sizeof(SchemaPool));
+    if( p ){
+      memset(p, 0, sizeof(SchemaPool));
+      p->cksum = cksum;
+      p->pNext = schemaPoolList;
+      schemaPoolList = p;
+
+      p->sSchema.schema_cookie = pSchema->schema_cookie;
+      p->sSchema.iGeneration = pSchema->iGeneration;
+      p->sSchema.file_format = pSchema->file_format;
+      p->sSchema.enc = pSchema->enc;
+      p->sSchema.cache_size = pSchema->cache_size;
+    }
+  }
+
+  if( p ) p->nRef++;
+
+  /* If the SchemaPool contains one or more free schemas at the moment, 
+  ** delete one of them. */
+  if( p && p->pSchema ){
+    Schema *pDel = p->pSchema;
+    p->pSchema = pDel->pNext;
+    schemaDelete(pDel);
+  }
+
+  sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+
+  db->aDb[iDb].pSPool = p;
+  return (p ? SQLITE_OK : SQLITE_NOMEM);
+}
+
+/*
+** If parameter iDb is 1 (the temp db), or if connection handle db was not
+** opened with the SQLITE_OPEN_SHARED_SCHEMA flag, this function is a no-op.
+** Otherwise, it disconnects from the schema-pool associated with database
+** iDb, assuming it is connected.
+**
+** If parameter bNew is true, then Db.pSchema is set to point to a new, empty,
+** Schema object obtained from sqlite3_malloc(). Or, if bNew is false, then
+** Db.pSchema is set to NULL before returning.
+**
+** If the bNew parameter is true, then this function may allocate memory. 
+** If the allocation attempt fails, then SQLITE_NOMEM is returned and the
+** schema-pool is not disconnected from. Or, if no OOM error occurs, 
+** SQLITE_OK is returned.
+*/
+int sqlite3SchemaDisconnect(sqlite3 *db, int iDb, int bNew){
+  int rc = SQLITE_OK;
+  if( IsSharedSchema(db) ){
+    Db *pDb = &db->aDb[iDb];
+    SchemaPool *pSPool = pDb->pSPool;
+    assert_schema_state_ok(db);
+    assert( pDb->pSchema );
+
+    if( pSPool==0 ){
+      assert( pDb->pVTable==0 );
+      assert( bNew==0 );
+      schemaDelete(pDb->pSchema);
+      pDb->pSchema = 0;
+    }else{
+      VTable *p;
+      VTable *pNext;
+      for(p=pDb->pVTable; p; p=pNext){
+        pNext = p->pNext;
+        sqlite3VtabUnlock(p);
+      }
+      pDb->pVTable = 0;
+      sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+      if( DbHasProperty(db, iDb, DB_SchemaLoaded) ){
+        schemaRelease(db, pDb);
+      }
+      if( bNew ){
+        Schema *pNew = sqlite3SchemaGet(db, 0);
+        if( pNew==0 ){
+          rc = SQLITE_NOMEM;
+        }else{
+          pDb->pSchema = pNew;
+        }
+      }
+      if( rc==SQLITE_OK ){
+        assert( pSPool->nRef>=1 );
+        pDb->pSPool = 0;
+        pSPool->nRef--;
+        if( pSPool->nRef<=0 ){
+          SchemaPool **pp;
+          while( pSPool->pSchema ){
+            Schema *pNext = pSPool->pSchema->pNext;
+            schemaDelete(pSPool->pSchema);
+            pSPool->pSchema = pNext;
+          }
+          for(pp=&schemaPoolList; (*pp)!=pSPool; pp=&((*pp)->pNext));
+          *pp = pSPool->pNext;
+          sqlite3_free(pSPool);
+        }
+      }
+      sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+    }
+  }
+  return rc;
+}
+
+/*
+** Extract and return a pointer to a schema object from the SchemaPool passed
+** as the only argument, if one is available. If one is not available, return
+** NULL.
+*/
+Schema *sqlite3SchemaExtract(SchemaPool *pSPool){
+  Schema *pRet = 0;
+  sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+  if( pSPool->pSchema ){
+    pRet = pSPool->pSchema;
+    pSPool->pSchema = pRet->pNext;
+    pRet->pNext = 0;
+  }
+  sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+  return pRet;
+}
+
+/*
+** Return all sharable schemas held by database handle db back to their
+** respective schema-pools. Db.pSchema variables are left pointing to
+** the static, empty, Schema object owned by each schema-pool.
+*/
+void sqlite3SchemaReleaseAll(sqlite3 *db){
+  int i;
+  assert_schema_state_ok(db);
+  sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+  for(i=0; i<db->nDb; i++){
+    if( i!=1 ){
+      Db *pDb = &db->aDb[i];
+      if( pDb->pSPool && DbHasProperty(db,i,DB_SchemaLoaded) ){
+        schemaRelease(db, pDb);
+      }
+    }
+  }
+  db->mDbFlags &= ~DBFLAG_FreeSchema;
+  sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+}
+
+/*
+** Release any sharable schema held by connection iDb of database handle
+** db. Db.pSchema is left pointing to the static, empty, Schema object
+** owned by the schema-pool.
+*/
+void sqlite3SchemaRelease(sqlite3 *db, int iDb){
+  Db *pDb = &db->aDb[iDb];
+  assert( iDb!=1 );
+  assert_schema_state_ok(db);
+  sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+  schemaRelease(db, pDb);
+  sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER) );
+}
+
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+
+/*
+** In most cases, this function finds and returns the schema associated 
+** with BTree handle pBt, creating a new one if necessary. However, if
+** the database handle was opened with the SQLITE_OPEN_SHARED_SCHEMA flag
+** specified, a new, empty, Schema object in memory obtained by 
+** sqlite3_malloc() is always returned.
 */
 Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
-  Schema * p;
-  if( pBt ){
-    p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);
+  Schema *p;
+  if( pBt && IsSharedSchema(db)==0 ){
+    p = (Schema*)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);
  }else{
-    p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));
+    p = (Schema*)sqlite3DbMallocZero(0, sizeof(Schema));
  }
  if( !p ){
    sqlite3OomFault(db);
@@ -310,6 +310,9 @@ static const char * const sqlite3azCompileOpt[] = {
 #ifdef SQLITE_ENABLE_SESSION
  "ENABLE_SESSION",
 #endif
+#if SQLITE_ENABLE_SHARED_SCHEMA
+  "ENABLE_SHARED_SCHEMA",
+#endif
 #ifdef SQLITE_ENABLE_SNAPSHOT
  "ENABLE_SNAPSHOT",
 #endif
@@ -1816,8 +1816,10 @@ static void sumFinalize(sqlite3_context *context){
    if( p->approx ){
      if( p->ovrfl ){
        sqlite3_result_error(context,"integer overflow",-1);
-      }else{
+      }else if( !sqlite3IsNaN(p->rErr) ){
        sqlite3_result_double(context, p->rSum+p->rErr);
+      }else{
+        sqlite3_result_double(context, p->rSum);
      }
    }else{
      sqlite3_result_int64(context, p->iSum);
@@ -1830,7 +1832,8 @@ static void avgFinalize(sqlite3_context *context){
  if( p && p->cnt>0 ){
    double r;
    if( p->approx ){
-      r = p->rSum+p->rErr;
+      r = p->rSum;
+      if( !sqlite3IsNaN(p->rErr) ) r += p->rErr;
    }else{
      r = (double)(p->iSum);
    }
@@ -1843,7 +1846,8 @@ static void totalFinalize(sqlite3_context *context){
  p = sqlite3_aggregate_context(context, 0);
  if( p ){
    if( p->approx ){
-      r = p->rSum+p->rErr;
+      r = p->rSum;
+      if( !sqlite3IsNaN(p->rErr) ) r += p->rErr;
    }else{
      r = (double)(p->iSum);
    }
@@ -2484,7 +2484,9 @@ static void jsonArrayLengthFunc(
  }
  if( pNode->eType==JSON_ARRAY ){
    while( 1 /*exit-by-break*/ ){
-      for(i=1; i<=pNode->n; n++){
+      i = 1;
+      while( i<=pNode->n ){
+        if( (pNode[i].jnFlags & JNODE_REMOVE)==0 ) n++;
        i += jsonNodeSize(&pNode[i]);
      }
      if( (pNode->jnFlags & JNODE_APPEND)==0 ) break;
@@ -2900,6 +2902,7 @@ static void jsonReplaceFunc(
  }
  pParse = jsonParseCached(ctx, argv[0], ctx, argc>1);
  if( pParse==0 ) return;
+  pParse->nJPRef++;
  for(i=1; i<(u32)argc; i+=2){
    zPath = (const char*)sqlite3_value_text(argv[i]);
    pParse->useMod = 1;
@@ -2912,6 +2915,7 @@ static void jsonReplaceFunc(
  jsonReturnJson(pParse, pParse->aNode, ctx, 1);
 replace_err:
  jsonDebugPrintParse(pParse);
+  jsonParseFree(pParse);
 }


@@ -2946,6 +2950,7 @@ static void jsonSetFunc(
  }
  pParse = jsonParseCached(ctx, argv[0], ctx, argc>1);
  if( pParse==0 ) return;
+  pParse->nJPRef++;
  for(i=1; i<(u32)argc; i+=2){
    zPath = (const char*)sqlite3_value_text(argv[i]);
    bApnd = 0;
@@ -2962,9 +2967,8 @@ static void jsonSetFunc(
  }
  jsonDebugPrintParse(pParse);
  jsonReturnJson(pParse, pParse->aNode, ctx, 1);
-
 jsonSetDone:
-  /* no cleanup required */;
+  jsonParseFree(pParse);
 }

 /*
@@ -1173,6 +1173,17 @@ static void disconnectAllVtab(sqlite3 *db){
        if( IsVirtual(pTab) ) sqlite3VtabDisconnect(db, pTab);
      }
    }
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    if( IsSharedSchema(db) && i!=1 ){
+      VTable *pVTable;
+      VTable *pNext;
+      for(pVTable=db->aDb[i].pVTable; pVTable; pVTable=pNext){
+        pNext = pVTable->pNext;
+        sqlite3VtabUnlock(pVTable);
+      }
+      db->aDb[i].pVTable = 0;
+    }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
  }
  for(p=sqliteHashFirst(&db->aModule); p; p=sqliteHashNext(p)){
    Module *pMod = (Module *)sqliteHashData(p);
@@ -1341,6 +1352,7 @@ void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
      sqlite3BtreeClose(pDb->pBt);
      pDb->pBt = 0;
      if( j!=1 ){
+        (void)sqlite3SchemaDisconnect(db, j, 0);
        pDb->pSchema = 0;
      }
    }
@@ -3805,7 +3817,7 @@ int sqlite3_table_column_metadata(
  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
 ){
-  int rc;
+  int rc = SQLITE_OK;
  char *zErrMsg = 0;
  Table *pTab = 0;
  Column *pCol = 0;
@@ -3815,7 +3827,7 @@ int sqlite3_table_column_metadata(
  int notnull = 0;
  int primarykey = 0;
  int autoinc = 0;
-
+  int bUnlock;

 #ifdef SQLITE_ENABLE_API_ARMOR
  if( !sqlite3SafetyCheckOk(db) || zTableName==0 ){
@@ -3825,14 +3837,29 @@ int sqlite3_table_column_metadata(

  /* Ensure the database schema has been loaded */
  sqlite3_mutex_enter(db->mutex);
+  bUnlock = sqlite3LockReusableSchema(db);
  sqlite3BtreeEnterAll(db);
-  rc = sqlite3Init(db, &zErrMsg);
-  if( SQLITE_OK!=rc ){
-    goto error_out;
+  if( IsSharedSchema(db)==0 ){
+    rc = sqlite3Init(db, &zErrMsg);
  }

  /* Locate the table in question */
-  pTab = sqlite3FindTable(db, zTableName, zDbName);
+  if( rc==SQLITE_OK ){
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    Parse sParse;                   /* Fake Parse object for FindTable */
+    Parse *pSaved = db->pParse;
+    memset(&sParse, 0, sizeof(sParse));
+    db->pParse = &sParse;
+#endif
+    pTab = sqlite3FindTable(db, zTableName, zDbName);
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    sqlite3_free(sParse.zErrMsg);
+    rc = sParse.rc;
+    db->pParse = pSaved;
+#endif
+  }
+  if( SQLITE_OK!=rc ) goto error_out;
+
  if( !pTab || IsView(pTab) ){
    pTab = 0;
    goto error_out;
@@ -3905,6 +3932,7 @@ error_out:
  sqlite3ErrorWithMsg(db, rc, (zErrMsg?"%s":0), zErrMsg);
  sqlite3DbFree(db, zErrMsg);
  rc = sqlite3ApiExit(db, rc);
+  sqlite3UnlockReusableSchema(db, bUnlock);
  sqlite3_mutex_leave(db->mutex);
  return rc;
 }
@@ -476,7 +476,13 @@ void sqlite3Pragma(

  /* Make sure the database schema is loaded if the pragma requires that */
  if( (pPragma->mPragFlg & PragFlg_NeedSchema)!=0 ){
-    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
+    if( IsSharedSchema(db) && (zDb || (pPragma->mPragFlg & PragFlg_OneSchema)) ){
+      assert( iDb>=0 && iDb<db->nDb );
+      pParse->rc = sqlite3SchemaLoad(db, iDb, 0, &pParse->zErrMsg);
+      if( pParse->rc ) goto pragma_out;
+    }else{
+      if( sqlite3ReadSchema(pParse) ) goto pragma_out;
+    }
  }

  /* Register the result column names for pragmas that return results */
@@ -2214,9 +2220,10 @@ void sqlite3Pragma(
  ** applications for any purpose.
  */
  case PragTyp_HEADER_VALUE: {
-    int iCookie = pPragma->iArg;  /* Which cookie to read or write */
+    int iCookie;                  /* Which cookie to read or write */
+    iCookie = pPragma->iArg & PRAGMA_HEADER_VALUE_MASK;     
    sqlite3VdbeUsesBtree(v, iDb);
-    if( zRight && (pPragma->mPragFlg & PragFlg_ReadOnly)==0 ){
+    if( zRight && (pPragma->iArg & PRAGMA_HEADER_VALUE_READONLY)==0 ){
      /* Write the specified cookie value */
      static const VdbeOpList setCookie[] = {
        { OP_Transaction,    0,  1,  0},    /* 0 */
@@ -56,12 +56,19 @@
 #define PragFlg_NeedSchema 0x01 /* Force schema load before running */
 #define PragFlg_NoColumns  0x02 /* OP_ResultRow called with zero columns */
 #define PragFlg_NoColumns1 0x04 /* zero columns if RHS argument is present */
-#define PragFlg_ReadOnly   0x08 /* Read-only HEADER_VALUE */
+#define PragFlg_OneSchema  0x08 /* Only a single schema required */
 #define PragFlg_Result0    0x10 /* Acts as query when no argument */
 #define PragFlg_Result1    0x20 /* Acts as query when has one argument */
 #define PragFlg_SchemaOpt  0x40 /* Schema restricts name search if present */
 #define PragFlg_SchemaReq  0x80 /* Schema required - "main" is default */

+/* For PragTyp_HEADER_VALUE pragmas the Pragma.iArg value is set
+** to the index of the header field to access (always 10 or less).
+** Ored with HEADER_VALUE_READONLY if the field is read only. */
+#define PRAGMA_HEADER_VALUE_READONLY 0x0100
+#define PRAGMA_HEADER_VALUE_MASK 0x00FF
+
+
 /* Names of columns for pragmas that return multi-column result
 ** or that return single-column results where the name of the
 ** result column is different from the name of the pragma
@@ -162,7 +169,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_AUTOVACUUM)
 {/* zName:     */ "auto_vacuum",
  /* ePragTyp:  */ PragTyp_AUTO_VACUUM,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 #endif
@@ -183,7 +190,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "cache_size",
  /* ePragTyp:  */ PragTyp_CACHE_SIZE,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 #endif
@@ -244,9 +251,9 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
 {/* zName:     */ "data_version",
  /* ePragTyp:  */ PragTyp_HEADER_VALUE,
-  /* ePragFlg:  */ PragFlg_ReadOnly|PragFlg_Result0,
+  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 0, 0,
-  /* iArg:      */ BTREE_DATA_VERSION },
+  /* iArg:      */ BTREE_DATA_VERSION|PRAGMA_HEADER_VALUE_READONLY },
 #endif
 #if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
 {/* zName:     */ "database_list",
@@ -258,7 +265,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && !defined(SQLITE_OMIT_DEPRECATED)
 {/* zName:     */ "default_cache_size",
  /* ePragTyp:  */ PragTyp_DEFAULT_CACHE_SIZE,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1|PragFlg_OneSchema,
  /* ColNames:  */ 55, 1,
  /* iArg:      */ 0 },
 #endif
@@ -295,7 +302,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_FOREIGN_KEY)
 {/* zName:     */ "foreign_key_list",
  /* ePragTyp:  */ PragTyp_FOREIGN_KEY_LIST,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result1|PragFlg_SchemaOpt|PragFlg_OneSchema,
  /* ColNames:  */ 0, 8,
  /* iArg:      */ 0 },
 #endif
@@ -311,9 +318,9 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
 {/* zName:     */ "freelist_count",
  /* ePragTyp:  */ PragTyp_HEADER_VALUE,
-  /* ePragFlg:  */ PragFlg_ReadOnly|PragFlg_Result0,
+  /* ePragFlg:  */ PragFlg_Result0,
  /* ColNames:  */ 0, 0,
-  /* iArg:      */ BTREE_FREE_PAGE_COUNT },
+  /* iArg:      */ BTREE_FREE_PAGE_COUNT|PRAGMA_HEADER_VALUE_READONLY },
 #endif
 #if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
 {/* zName:     */ "full_column_names",
@@ -353,7 +360,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_AUTOVACUUM)
 {/* zName:     */ "incremental_vacuum",
  /* ePragTyp:  */ PragTyp_INCREMENTAL_VACUUM,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_NoColumns,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_NoColumns|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 #endif
@@ -384,7 +391,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "journal_mode",
  /* ePragTyp:  */ PragTyp_JOURNAL_MODE,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 {/* zName:     */ "journal_size_limit",
@@ -422,7 +429,7 @@ static const PragmaName aPragmaName[] = {
  /* iArg:      */ 0 },
 {/* zName:     */ "max_page_count",
  /* ePragTyp:  */ PragTyp_PAGE_COUNT,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 {/* zName:     */ "mmap_size",
@@ -450,7 +457,7 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "page_count",
  /* ePragTyp:  */ PragTyp_PAGE_COUNT,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 {/* zName:     */ "page_size",
@@ -549,14 +556,14 @@ static const PragmaName aPragmaName[] = {
 #if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS) && defined(SQLITE_DEBUG)
 {/* zName:     */ "stats",
  /* ePragTyp:  */ PragTyp_STATS,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_OneSchema,
  /* ColNames:  */ 33, 5,
  /* iArg:      */ 0 },
 #endif
 #if !defined(SQLITE_OMIT_PAGER_PRAGMAS)
 {/* zName:     */ "synchronous",
  /* ePragTyp:  */ PragTyp_SYNCHRONOUS,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_SchemaReq|PragFlg_NoColumns1|PragFlg_OneSchema,
  /* ColNames:  */ 0, 0,
  /* iArg:      */ 0 },
 #endif
@@ -645,7 +652,7 @@ static const PragmaName aPragmaName[] = {
  /* iArg:      */ 0 },
 {/* zName:     */ "wal_checkpoint",
  /* ePragTyp:  */ PragTyp_WAL_CHECKPOINT,
-  /* ePragFlg:  */ PragFlg_NeedSchema,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_OneSchema,
  /* ColNames:  */ 50, 3,
  /* iArg:      */ 0 },
 #endif
@@ -43,6 +43,11 @@ static void corruptSchema(
    pData->rc = SQLITE_ERROR;
  }else if( db->flags & SQLITE_WriteSchema ){
    pData->rc = SQLITE_CORRUPT_BKPT;
+  }else if( IsSharedSchema(db) 
+         && 0==sqlite3StrNICmp(zExtra, "malformed database schema", 17)
+  ){
+    pData->rc = SQLITE_CORRUPT_BKPT;
+    *pData->pzErrMsg = sqlite3DbStrDup(db, zExtra);
  }else{
    char *z;
    const char *zObj = azObj[1] ? azObj[1] : "?";
@@ -53,6 +58,28 @@ static void corruptSchema(
  }
 }

+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+/*
+** Update the Schema.cksum checksum to account for the database object
+** specified by the three arguments following the first.
+*/
+static void schemaUpdateChecksum(
+  InitData *pData,                /* Schema parse context */
+  const char *zName,              /* Name of new database object */
+  const char *zRoot,              /* Root page of new database object */
+  const char *zSql                /* SQL used to create new database object */
+){
+  int i;
+  u64 cksum = pData->cksum;
+  if( zName ){
+    for(i=0; zName[i]; i++) cksum += (cksum<<3) + zName[i];
+  }
+  if( zRoot ) for(i=0; zRoot[i]; i++) cksum += (cksum<<3) + zRoot[i];
+  if( zSql ) for(i=0; zSql[i]; i++) cksum += (cksum<<3) + zSql[i];
+  pData->cksum = cksum;
+}
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+
 /*
 ** Check to see if any sibling index (another index on the same table)
 ** of pIndex has the same root page number, and if it does, return true.
@@ -76,6 +103,15 @@ static int sqlite3Prepare(
  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
  const char **pzTail       /* OUT: End of parsed string */
 );
+static int sqlite3LockAndPrepare(
+  sqlite3 *db,              /* Database handle. */
+  const char *zSql,         /* UTF-8 encoded SQL statement. */
+  int nBytes,               /* Length of zSql in bytes. */
+  u32 prepFlags,            /* Zero or more SQLITE_PREPARE_* flags */
+  Vdbe *pReprepare,         /* VM being reprepared */
+  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
+  const char **pzTail       /* OUT: End of parsed string */
+);


 /*
@@ -141,7 +177,11 @@ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
    db->init.orphanTrigger = 0;
    db->init.azInit = (const char**)argv;
    pStmt = 0;
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    TESTONLY(rcp = ) sqlite3LockAndPrepare(db, argv[4], -1, 0, 0, &pStmt, 0);
+#else
    TESTONLY(rcp = ) sqlite3Prepare(db, argv[4], -1, 0, 0, &pStmt, 0);
+#endif
    rc = db->errCode;
    assert( (rc&0xFF)==(rcp&0xFF) );
    db->init.iDb = saved_iDb;
@@ -153,7 +193,11 @@ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
        if( rc > pData->rc ) pData->rc = rc;
        if( rc==SQLITE_NOMEM ){
          sqlite3OomFault(db);
-        }else if( rc!=SQLITE_INTERRUPT && (rc&0xFF)!=SQLITE_LOCKED ){
+        }else if( rc!=SQLITE_INTERRUPT && (rc&0xFF)!=SQLITE_LOCKED
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+               && (rc&0xFF)!=SQLITE_IOERR
+#endif
+        ){
          corruptSchema(pData, argv, sqlite3_errmsg(db));
        }
      }
@@ -184,6 +228,12 @@ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
      }
    }
  }
+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  if( IsSharedSchema(db) && iDb!=1 ){
+    schemaUpdateChecksum(pData, argv[0], argv[1], argv[2]);
+  }
+#endif
  return 0;
 }

@@ -211,10 +261,28 @@ int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){

  assert( (db->mDbFlags & DBFLAG_SchemaKnownOk)==0 );
  assert( iDb>=0 && iDb<db->nDb );
-  assert( db->aDb[iDb].pSchema );
+  assert( db->aDb[iDb].pSchema || (IsSharedSchema(db) && iDb!=1) );
  assert( sqlite3_mutex_held(db->mutex) );
  assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

+  pDb = &db->aDb[iDb];
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  assert( pDb->pSPool==0 || IsSharedSchema(db) );
+  if( pDb->pSPool ){
+    /* See if there is a free schema object in the schema-pool. If not,
+    ** disconnect from said schema pool and continue. This function will
+    ** connect to a (possibly different) schema-pool before returning. */
+    Schema *pNew = sqlite3SchemaExtract(pDb->pSPool);
+    if( pNew ){
+      pDb->pSchema = pNew;
+      return SQLITE_OK;
+    }
+    rc = sqlite3SchemaDisconnect(db, iDb, 1);
+    if( rc!=SQLITE_OK ) goto error_out;
+    assert( pDb->pSchema && pDb->pSPool==0 );
+  }
+#endif
+
  db->init.busy = 1;

  /* Construct the in-memory representation schema tables (sqlite_schema or
@@ -235,6 +303,7 @@ int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){
  initData.pzErrMsg = pzErrMsg;
  initData.mInitFlags = mFlags;
  initData.nInitRow = 0;
+  initData.cksum = 0;
  initData.mxPage = 0;
  sqlite3InitCallback(&initData, 5, (char **)azArg, 0);
  db->mDbFlags &= mask;
@@ -245,7 +314,6 @@ int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){

  /* Create a cursor to hold the database open
  */
-  pDb = &db->aDb[iDb];
  if( pDb->pBt==0 ){
    assert( iDb==1 );
    DbSetProperty(db, 1, DB_SchemaLoaded);
@@ -411,6 +479,10 @@ int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){
    rc = SQLITE_OK;
  }

+  if( rc==SQLITE_OK && iDb!=1 && IsSharedSchema(db) ){
+    rc = sqlite3SchemaConnect(db, iDb, initData.cksum);
+  }
+
  /* Jump here for an error that occurs after successfully allocating
  ** curMain and calling sqlite3BtreeEnter(). For an error that occurs
  ** before that point, jump to error_out.
@@ -432,6 +504,35 @@ error_out:
  return rc;
 }

+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+/*
+** If this is a SHARED_SCHEMA connection and the DBFLAG_SchemaInUse flag
+** is not currently set, set it and return non-zero. Otherwise, return 0.
+*/
+int sqlite3LockReusableSchema(sqlite3 *db){
+  if( IsSharedSchema(db) && (db->mDbFlags & DBFLAG_SchemaInuse)==0 ){
+    db->mDbFlags |= DBFLAG_SchemaInuse;
+    return 1;
+  }
+  return 0;
+}
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+/*
+** This function is a no-op for non-SHARED_SCHEMA connections, or if bRelease
+** is zero. Otherwise, clear the DBFLAG_SchemaInuse flag and release all
+** schema references currently held.
+*/
+void sqlite3UnlockReusableSchema(sqlite3 *db, int bRelease){
+  if( bRelease ){
+    db->mDbFlags &= ~DBFLAG_SchemaInuse;
+    sqlite3SchemaReleaseAll(db);
+  }
+}
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+
 /*
 ** Initialize all database files - the main database file, the file
 ** used to store temporary tables, and any additional database files
@@ -442,8 +543,12 @@ error_out:
 ** bit is set in the flags field of the Db structure. 
 */
 int sqlite3Init(sqlite3 *db, char **pzErrMsg){
-  int i, rc;
+  int rc = SQLITE_OK;
+  int bReleaseSchema;
+  int i;
  int commit_internal = !(db->mDbFlags&DBFLAG_SchemaChange);
+
+  bReleaseSchema = sqlite3LockReusableSchema(db);
  
  assert( sqlite3_mutex_held(db->mutex) );
  assert( sqlite3BtreeHoldsMutex(db->aDb[0].pBt) );
@@ -453,20 +558,19 @@ int sqlite3Init(sqlite3 *db, char **pzErrMsg){
  /* Do the main schema first */
  if( !DbHasProperty(db, 0, DB_SchemaLoaded) ){
    rc = sqlite3InitOne(db, 0, pzErrMsg, 0);
-    if( rc ) return rc;
  }
  /* All other schemas after the main schema. The "temp" schema must be last */
-  for(i=db->nDb-1; i>0; i--){
+  for(i=db->nDb-1; rc==SQLITE_OK && i>0; i--){
    assert( i==1 || sqlite3BtreeHoldsMutex(db->aDb[i].pBt) );
    if( !DbHasProperty(db, i, DB_SchemaLoaded) ){
      rc = sqlite3InitOne(db, i, pzErrMsg, 0);
-      if( rc ) return rc;
    }
  }
-  if( commit_internal ){
+  if( rc==SQLITE_OK && commit_internal ){
    sqlite3CommitInternalChanges(db);
  }
-  return SQLITE_OK;
+  sqlite3UnlockReusableSchema(db, bReleaseSchema);
+  return rc;
 }

 /*
@@ -478,11 +582,12 @@ int sqlite3ReadSchema(Parse *pParse){
  sqlite3 *db = pParse->db;
  assert( sqlite3_mutex_held(db->mutex) );
  if( !db->init.busy ){
+    db->mDbFlags |= DBFLAG_FreeSchema;      /* For sharable-schema mode */
    rc = sqlite3Init(db, &pParse->zErrMsg);
    if( rc!=SQLITE_OK ){
      pParse->rc = rc;
      pParse->nErr++;
-    }else if( db->noSharedCache ){
+    }else if( db->noSharedCache && !IsSharedSchema(db) ){
      db->mDbFlags |= DBFLAG_SchemaKnownOk;
    }
  }
@@ -508,6 +613,10 @@ static void schemaIsValid(Parse *pParse){
    Btree *pBt = db->aDb[iDb].pBt;     /* Btree database to read cookie from */
    if( pBt==0 ) continue;

+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    if( IsSharedSchema(db) && iDb!=1 && db->aDb[iDb].pSPool==0 ) continue;
+#endif
+
    /* If there is not already a read-only (or read-write) transaction opened
    ** on the b-tree database, open one now. If a transaction is opened, it 
    ** will be closed immediately after reading the meta-value. */
@@ -846,6 +955,7 @@ static int sqlite3LockAndPrepare(
 ){
  int rc;
  int cnt = 0;
+  int bReleaseSchema = 0;

 #ifdef SQLITE_ENABLE_API_ARMOR
  if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
@@ -855,6 +965,7 @@ static int sqlite3LockAndPrepare(
    return SQLITE_MISUSE_BKPT;
  }
  sqlite3_mutex_enter(db->mutex);
+  bReleaseSchema = sqlite3LockReusableSchema(db);
  sqlite3BtreeEnterAll(db);
  do{
    /* Make multiple attempts to compile the SQL, until it either succeeds
@@ -865,7 +976,11 @@ static int sqlite3LockAndPrepare(
    if( rc==SQLITE_OK || db->mallocFailed ) break;
  }while( (rc==SQLITE_ERROR_RETRY && (cnt++)<SQLITE_MAX_PREPARE_RETRY)
       || (rc==SQLITE_SCHEMA && (sqlite3ResetOneSchema(db,-1), cnt++)==0) );
+
  sqlite3BtreeLeaveAll(db);
+
+  sqlite3UnlockReusableSchema(db, bReleaseSchema);
+
  rc = sqlite3ApiExit(db, rc);
  assert( (rc&db->errMask)==rc );
  db->busyHandler.nBusy = 0;
@@ -5301,12 +5301,12 @@ static int disableUnusedSubqueryResultColumns(SrcItem *pItem){
  assert( pItem->pSelect!=0 );
  pSub = pItem->pSelect;
  assert( pSub->pEList->nExpr==pTab->nCol );
-  if( (pSub->selFlags & (SF_Distinct|SF_Aggregate))!=0 ){
-    testcase( pSub->selFlags & SF_Distinct );
-    testcase( pSub->selFlags & SF_Aggregate );
-    return 0;
-  }
  for(pX=pSub; pX; pX=pX->pPrior){
+    if( (pX->selFlags & (SF_Distinct|SF_Aggregate))!=0 ){
+      testcase( pX->selFlags & SF_Distinct );
+      testcase( pX->selFlags & SF_Aggregate );
+      return 0;
+    }
    if( pX->pPrior && pX->op!=TK_ALL ){
      /* This optimization does not work for compound subqueries that
      ** use UNION, INTERSECT, or EXCEPT.  Only UNION ALL is allowed. */
@@ -1242,7 +1242,7 @@ static void shellDtostr(
  char z[400];
  if( n<1 ) n = 1;
  if( n>350 ) n = 350;
-  sprintf(z, "%#+.*e", n, r);
+  snprintf(z, sizeof(z)-1, "%#+.*e", n, r);
  sqlite3_result_text(pCtx, z, -1, SQLITE_TRANSIENT);
 }

@@ -1542,13 +1542,14 @@ static ShellState shellState;

 /* Allowed values for ShellState.openMode
 */
-#define SHELL_OPEN_UNSPEC      0      /* No open-mode specified */
-#define SHELL_OPEN_NORMAL      1      /* Normal database file */
-#define SHELL_OPEN_APPENDVFS   2      /* Use appendvfs */
-#define SHELL_OPEN_ZIPFILE     3      /* Use the zipfile virtual table */
-#define SHELL_OPEN_READONLY    4      /* Open a normal database read-only */
-#define SHELL_OPEN_DESERIALIZE 5      /* Open using sqlite3_deserialize() */
-#define SHELL_OPEN_HEXDB       6      /* Use "dbtotxt" output as data source */
+#define SHELL_OPEN_UNSPEC       0     /* No open-mode specified */
+#define SHELL_OPEN_NORMAL       1     /* Normal database file */
+#define SHELL_OPEN_APPENDVFS    2     /* Use appendvfs */
+#define SHELL_OPEN_ZIPFILE      3     /* Use the zipfile virtual table */
+#define SHELL_OPEN_READONLY     4     /* Open a normal database read-only */
+#define SHELL_OPEN_DESERIALIZE  5     /* Open using sqlite3_deserialize() */
+#define SHELL_OPEN_HEXDB        6     /* Use "dbtotxt" output as data source */
+#define SHELL_OPEN_SHAREDSCHEMA 7     /* Open for schema reuse */

 /* Allowed values for ShellState.eTraceType
 */
@@ -5007,6 +5008,12 @@ static const char *(azHelp[]) = {
  "      --sha3-384            Use the sha3-384 algorithm",
  "      --sha3-512            Use the sha3-512 algorithm",
  "    Any other argument is a LIKE pattern for tables to hash",
+#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_ENABLE_DBPAGE_VTAB)
+  ".shared-schema CMD DB1 DB2 ...",
+  "    Commands:",
+  "       check                Determine if DB1, DB2, etc have identical schemas",
+  "       fix                  Attempt to make DB1, DB2, etc compatible",
+#endif
 #if !defined(SQLITE_NOHAVE_SYSTEM) && !defined(SQLITE_SHELL_FIDDLE)
  ".shell CMD ARGS...       Run CMD ARGS... in a system shell",
 #endif
@@ -5450,6 +5457,11 @@ static void open_db(ShellState *p, int openFlags){
            SQLITE_OPEN_READONLY|p->openFlags, 0);
        break;
      }
+      case SHELL_OPEN_SHAREDSCHEMA: {
+        sqlite3_open_v2(p->pAuxDb->zDbFilename, &p->db,
+          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_SHARED_SCHEMA,0);
+        break;
+      }
      case SHELL_OPEN_UNSPEC:
      case SHELL_OPEN_NORMAL: {
        sqlite3_open_v2(zDbFilename, &p->db,
@@ -7713,8 +7725,277 @@ end_ar_command:
 *******************************************************************************/
 #endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_HAVE_ZLIB) */

-#if SQLITE_SHELL_HAVE_RECOVER
+/*
+** If (*pRc) is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, the SQL statement or statements in zSql are executed using
+** database connection db and the error code written to *pRc before
+** this function returns.
+*/
+static void shellExec(sqlite3 *db, int *pRc, const char *zSql){
+  int rc = *pRc;
+  if( rc==SQLITE_OK ){
+    char *zErr = 0;
+    rc = sqlite3_exec(db, zSql, 0, 0, &zErr);
+    if( rc!=SQLITE_OK ){
+      raw_printf(stderr, "SQL error: %s\n", zErr);
+    }
+    sqlite3_free(zErr);
+    *pRc = rc;
+  }
+}

+/*
+** Like shellExec(), except that zFmt is a printf() style format string.
+*/
+static void shellExecPrintf(sqlite3 *db, int *pRc, const char *zFmt, ...){
+  char *z = 0;
+  if( *pRc==SQLITE_OK ){
+    va_list ap;
+    va_start(ap, zFmt);
+    z = sqlite3_vmprintf(zFmt, ap);
+    va_end(ap);
+    if( z==0 ){
+      *pRc = SQLITE_NOMEM;
+    }else{
+      shellExec(db, pRc, z);
+    }
+    sqlite3_free(z);
+  }
+}
+
+static int sharedSchemaFix(ShellState *pState, const char *zDb){
+  int rc = SQLITE_OK;
+  i64 iLast = 0;
+  int iCookie = 0;
+  int iAutoVacuum = 0;
+  sqlite3_stmt *pStmt = 0;
+
+  shellExecPrintf(pState->db, &rc, "ATTACH '%q' AS _shared_schema_tmp", zDb);
+  shellExecPrintf(pState->db, &rc, "PRAGMA writable_schema = 1");
+  shellExecPrintf(pState->db, &rc, "BEGIN");
+  shellPreparePrintf(pState->db, &rc, &pStmt, 
+      "SELECT max(rowid) FROM _shared_schema_tmp.sqlite_master"
+  );
+  sqlite3_step(pStmt);
+  iLast = sqlite3_column_int64(pStmt, 0);
+  shellFinalize(&rc, pStmt);
+  shellPreparePrintf(pState->db, &rc, &pStmt,
+      "INSERT INTO _shared_schema_tmp.sqlite_master SELECT "
+      "  type, name, tbl_name, ("
+      "    SELECT rootpage FROM _shared_schema_tmp.sqlite_master WHERE "
+      "      type IS o.type AND name IS o.name AND rowid<=?"
+      "  ), sql FROM main.sqlite_master AS o"
+  );
+  sqlite3_bind_int64(pStmt, 1, iLast);
+  sqlite3_step(pStmt);
+  shellFinalize(&rc, pStmt);
+
+  shellExecPrintf(pState->db, &rc,
+      "DELETE FROM _shared_schema_tmp.sqlite_master WHERE rowid<=%lld",
+      iLast
+  );
+  shellExecPrintf(pState->db, &rc, "COMMIT");
+  sqlite3_exec(pState->db, "PRAGMA writable_schema = 0", 0, 0, 0);
+
+  /* Copy the auto-vacuum setting from main to the target db */
+  shellPreparePrintf(pState->db, &rc, &pStmt, "PRAGMA main.auto_vacuum");
+  sqlite3_step(pStmt);
+  iAutoVacuum = sqlite3_column_int(pStmt, 0);
+  shellFinalize(&rc, pStmt);
+  shellExecPrintf(pState->db, &rc, 
+      "PRAGMA _shared_schema_tmp.auto_vacuum = %d", iAutoVacuum
+  );
+
+  /* Vacuum the db in order to standardize the rootpage numbers. */
+  shellExecPrintf(pState->db, &rc, "VACUUM _shared_schema_tmp");
+
+  /* Set the schema-cookie value to the same as database "main" */
+  shellPreparePrintf(pState->db, &rc, &pStmt, "PRAGMA main.schema_version");
+  sqlite3_step(pStmt);
+  iCookie = sqlite3_column_int(pStmt, 0);
+  shellFinalize(&rc, pStmt);
+  shellExecPrintf(pState->db, &rc, 
+      "PRAGMA _shared_schema_tmp.schema_version = %d", iCookie
+  );
+
+  sqlite3_exec(pState->db, "DETACH _shared_schema_tmp", 0, 0, 0);
+  return rc;
+}
+
+static int sharedSchemaCheck(ShellState *pState, const char *zDb, int *peFix){
+  int rc = SQLITE_OK;
+  int bFailed = 0;
+  sqlite3_stmt *pStmt = 0;
+
+  if( peFix ) *peFix = 0;
+  shellExecPrintf(pState->db, &rc, "ATTACH '%q' AS _shared_schema_tmp", zDb);
+
+  /* Check if this database has the same set of objects as the current db */
+  shellPreparePrintf(pState->db, &rc, &pStmt, 
+    "SELECT type, name FROM _shared_schema_tmp.sqlite_master AS o "
+    "WHERE NOT EXISTS ("
+    "  SELECT 1 FROM main.sqlite_master "
+    "    WHERE name IS o.name AND type IS o.type"
+    ")"
+    " UNION ALL "
+    "SELECT type, name FROM main.sqlite_master AS o "
+    "WHERE NOT EXISTS ("
+    "  SELECT 1 FROM _shared_schema_tmp.sqlite_master "
+    "    WHERE name IS o.name AND type IS o.type"
+    ")"
+  );
+  if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+    utf8_printf(pState->out, "%s is NOT compatible (objects)\n", zDb);
+    bFailed = 1;
+  }
+  shellFinalize(&rc, pStmt);
+
+  /* Check if this database has the same set of SQL statements as the 
+  ** current db. */
+  if( bFailed==0 ){
+    shellPreparePrintf(pState->db, &rc, &pStmt, 
+        "SELECT 1 FROM _shared_schema_tmp.sqlite_master AS o "
+        "WHERE sql IS NOT ("
+        "  SELECT sql FROM main.sqlite_master "
+        "    WHERE name IS o.name AND type IS o.type"
+        ")"
+    );
+    if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      utf8_printf(pState->out, "%s is NOT compatible (SQL)\n", zDb);
+      bFailed = 1;
+    }
+    shellFinalize(&rc, pStmt);
+  }
+
+  /* Check if this database has the same set of root pages as the current 
+  ** db. */
+  if( bFailed==0 ){
+    shellPreparePrintf(pState->db, &rc, &pStmt, 
+        "SELECT 1 FROM _shared_schema_tmp.sqlite_master AS o "
+        "WHERE rootpage IS NOT ("
+        "  SELECT rootpage FROM main.sqlite_master "
+        "    WHERE name IS o.name AND type IS o.type"
+        ")"
+    );
+    if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      if( peFix==0 ){
+        utf8_printf(pState->out, "%s is NOT compatible (root pages)\n", zDb);
+      }
+      bFailed = 1;
+      if( peFix ) *peFix = 1;
+    }
+    shellFinalize(&rc, pStmt);
+  }
+
+  if( bFailed==0 ){
+    shellPreparePrintf(pState->db, &rc, &pStmt, 
+        "SELECT 1 WHERE ("
+        "  SELECT group_concat(rootpage || '.' || name || '.' || sql, '.') "
+        "  FROM _shared_schema_tmp.sqlite_master"
+        ") IS NOT ("
+        "  SELECT group_concat(rootpage || '.' || name || '.' || sql, '.') "
+        "  FROM main.sqlite_master"
+        ")"
+    );
+    if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      if( peFix==0 ){
+        utf8_printf(pState->out, 
+            "%s is NOT compatible (order of sqlite_master rows)\n", zDb
+        );
+      }
+      bFailed = 1;
+      if( peFix ) *peFix = 2;
+    }
+    shellFinalize(&rc, pStmt);
+  }
+
+  if( bFailed==0 ){
+    int iMain = -1;
+    int iNew = +1;
+    shellPreparePrintf(pState->db, &rc, &pStmt, 
+        "PRAGMA main.schema_version"
+    );
+    if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      iMain = sqlite3_column_int(pStmt, 0);
+    }
+    shellFinalize(&rc, pStmt);
+    shellPreparePrintf(pState->db, &rc, &pStmt, 
+        "PRAGMA _shared_schema_tmp.schema_version"
+    );
+    if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      iNew = sqlite3_column_int(pStmt, 0);
+    }
+    shellFinalize(&rc, pStmt);
+    if( rc==SQLITE_OK && iMain!=iNew ){
+      if( peFix==0 ){
+        utf8_printf(pState->out, 
+            "%s is NOT compatible (schema cookie)\n", zDb
+        );
+      }
+      bFailed = 1;
+      if( peFix ) *peFix = 3;
+    }
+  }
+
+  if( rc==SQLITE_OK && bFailed==0 ){
+    utf8_printf(pState->out, "%s is compatible\n", zDb);
+  }
+
+  sqlite3_exec(pState->db, "DETACH _shared_schema_tmp", 0, 0, 0);
+  return rc;
+}
+
+/*
+** .shared-schema check|fix DB1 DB2...
+*/
+static int sharedSchemaDotCommand(
+  ShellState *pState,             /* Current shell tool state */
+  char **azArg,                   /* Array of arguments passed to dot command */
+  int nArg                        /* Number of entries in azArg[] */
+){
+  int rc = SQLITE_OK;
+  int bFix = 0;                   /* Fix databases if possible */
+  int n1;
+  int i;
+  if( nArg<3 ){
+    goto shared_schema_usage;
+  }
+
+  n1 = (int)strlen(azArg[1]);
+  if( n1>0 && n1<=3 && memcmp("fix", azArg[1], n1)==0 ){
+    bFix = 1;
+  }else if( n1==0 || n1>5 || memcmp("check", azArg[1], n1) ){
+    goto shared_schema_usage;
+  }
+
+  for(i=2; rc==SQLITE_OK && i<nArg; i++){
+    int eFix = 0;
+    rc = sharedSchemaCheck(pState, azArg[i], bFix ? &eFix : 0);
+    if( rc==SQLITE_OK && bFix && eFix ){
+      utf8_printf(pState->out, "Fixing %s... ", azArg[i]);
+      fflush(pState->out);
+      rc = sharedSchemaFix(pState, azArg[i]);
+      if( rc==SQLITE_OK ){
+        rc = sharedSchemaCheck(pState, azArg[i], &eFix);
+        if( rc==SQLITE_OK && eFix ){
+          utf8_printf(pState->out, "VACUUMing main... ");
+          fflush(pState->out);
+          rc = sqlite3_exec(pState->db, "VACUUM main", 0, 0, 0);
+          if( rc==SQLITE_OK ){
+            rc = sharedSchemaCheck(pState, azArg[i], 0);
+          }
+        }
+      }
+    }
+  }
+
+  return rc;
+ shared_schema_usage:
+  raw_printf(stderr, "usage: .shared-schema check|fix DB1 DB2...\n");
+  return SQLITE_ERROR;
+}
+
+#if SQLITE_SHELL_HAVE_RECOVER
 /*
 ** This function is used as a callback by the recover extension. Simply
 ** print the supplied SQL statement to stdout.
@@ -10682,6 +10963,13 @@ static int do_meta_command(char *zLine, ShellState *p){
    sqlite3_free(zSql);
  }else

+#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_ENABLE_DBPAGE_VTAB)
+  if( c=='s' && strncmp(azArg[0], "shared-schema", n)==0 ){
+    open_db(p, 0);
+    sharedSchemaDotCommand(p, azArg, nArg);
+  }else
+#endif
+
 #if !defined(SQLITE_NOHAVE_SYSTEM) && !defined(SQLITE_SHELL_FIDDLE)
  if( c=='s'
   && (cli_strncmp(azArg[0], "shell", n)==0
@@ -12318,6 +12606,8 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
 #endif
    }else if( cli_strcmp(z,"-readonly")==0 ){
      data.openMode = SHELL_OPEN_READONLY;
+    }else if( strcmp(z,"-sharedschema")==0 ){
+      data.openMode = SHELL_OPEN_SHAREDSCHEMA;
    }else if( cli_strcmp(z,"-nofollow")==0 ){
      data.openFlags = SQLITE_OPEN_NOFOLLOW;
 #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_HAVE_ZLIB)
@@ -12448,6 +12738,8 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
 #endif
    }else if( cli_strcmp(z,"-readonly")==0 ){
      data.openMode = SHELL_OPEN_READONLY;
+    }else if( strcmp(z,"-sharedschema")==0 ){
+      data.openMode = SHELL_OPEN_SHAREDSCHEMA;
    }else if( cli_strcmp(z,"-nofollow")==0 ){
      data.openFlags |= SQLITE_OPEN_NOFOLLOW;
    }else if( cli_strcmp(z,"-ascii")==0 ){
@@ -614,10 +614,11 @@ int sqlite3_exec(
 #define SQLITE_OPEN_EXRESCODE        0x02000000  /* Extended result codes */

 /* Reserved:                         0x00F00000 */
+#define SQLITE_OPEN_SHARED_SCHEMA    0x01000000  /* Ok for sqlite3_open_v2() */
+
 /* Legacy compatibility: */
 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */

-
 /*
 ** CAPI3REF: Device Characteristics
 **
@@ -1258,6 +1258,7 @@ typedef struct CteUse CteUse;
 typedef struct Db Db;
 typedef struct DbFixer DbFixer;
 typedef struct Schema Schema;
+typedef struct SchemaPool SchemaPool;
 typedef struct Expr Expr;
 typedef struct ExprList ExprList;
 typedef struct FKey FKey;
@@ -1400,6 +1401,10 @@ struct Db {
  u8 safety_level;     /* How aggressive at syncing data to disk */
  u8 bSyncSet;         /* True if "PRAGMA synchronous=N" has been run */
  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  SchemaPool *pSPool;  /* For REUSE_SCHEMA mode */
+  VTable *pVTable;     /* List of all VTable objects (REUSE_SCHEMA mode only) */
+#endif
 };

 /*
@@ -1431,6 +1436,9 @@ struct Schema {
  u8 enc;              /* Text encoding used by this database */
  u16 schemaFlags;     /* Flags associated with this schema */
  int cache_size;      /* Number of pages to use in the cache */
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  Schema *pNext;       /* Next Schema object SchemaPool (REUSE_SCHEMA) */
+#endif
 };

 /*
@@ -1756,6 +1764,12 @@ struct sqlite3 {
 #endif
 };

+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+# define IsSharedSchema(db) (((db)->openFlags & SQLITE_OPEN_SHARED_SCHEMA)!=0)
+#else
+# define IsSharedSchema(db) 0
+#endif
+
 /*
 ** A macro to discover the encoding of a database.
 */
@@ -1838,6 +1852,9 @@ struct sqlite3 {
 #define DBFLAG_InternalFunc   0x0020  /* Allow use of internal functions */
 #define DBFLAG_EncodingFixed  0x0040  /* No longer possible to change enc. */

+#define DBFLAG_SchemaInuse    0x0080  /* Do not release sharable schemas */
+#define DBFLAG_FreeSchema     0x0100  /* Free extra shared schemas on release */
+
 /*
 ** Bits of the sqlite3.dbOptFlags field that are used by the
 ** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
@@ -2351,6 +2368,9 @@ struct VTable {
  u8 eVtabRisk;             /* Riskiness of allowing hacker access */
  int iSavepoint;           /* Depth of the SAVEPOINT stack */
  VTable *pNext;            /* Next in linked list (see above) */
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  char *zName;              /* Table name (REUSE_SCHEMA mode) */
+#endif
 };

 /* Allowed values for VTable.eVtabRisk
@@ -3958,6 +3978,9 @@ struct Trigger {
  Schema *pTabSchema;     /* Schema containing the table */
  TriggerStep *step_list; /* Link list of trigger program steps             */
  Trigger *pNext;         /* Next trigger associated with the table */
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  char *zTabSchema;       /* Temp triggers in IsSharedSchema() dbs only */
+#endif
 };

 /*
@@ -4093,6 +4116,7 @@ typedef struct {
  int rc;             /* Result code stored here */
  u32 mInitFlags;     /* Flags controlling error messages */
  u32 nInitRow;       /* Number of rows processed */
+  u64 cksum;          /* Schema checksum for REUSE_SCHEMA mode */
  Pgno mxPage;        /* Maximum page number.  0 for no limit. */
 } InitData;

@@ -5281,6 +5305,29 @@ void sqlite3DefaultRowEst(Index*);
 void sqlite3RegisterLikeFunctions(sqlite3*, int);
 int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
 void sqlite3SchemaClear(void *);
+void sqlite3SchemaClearOrDisconnect(sqlite3*, int);
+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA 
+int sqlite3SchemaConnect(sqlite3*, int, u64);
+int sqlite3SchemaDisconnect(sqlite3 *, int, int);
+Schema *sqlite3SchemaExtract(SchemaPool*);
+int sqlite3SchemaLoad(sqlite3*, int, int*, char**);
+void sqlite3SchemaReleaseAll(sqlite3*);
+void sqlite3SchemaRelease(sqlite3*, int);
+void sqlite3SchemaAdjustUsed(sqlite3*, int, int, int*);
+void sqlite3SchemaWritable(Parse*, int);
+void sqlite3UnlockReusableSchema(sqlite3 *db, int bRelease);
+int sqlite3LockReusableSchema(sqlite3 *db);
+#else
+# define sqlite3SchemaWritable(x,y)
+# define sqlite3UnlockReusableSchema(x,y) (void)(y)
+# define sqlite3LockReusableSchema(x) 0
+# define sqlite3SchemaDisconnect(x,y,z) SQLITE_OK
+# define sqlite3SchemaLoad(w,x,y,z) SQLITE_OK
+# define sqlite3SchemaRelease(y,z)
+# define sqlite3SchemaConnect(x,y,z) SQLITE_OK
+#endif
+
 Schema *sqlite3SchemaGet(sqlite3 *, Btree *);
 int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
 KeyInfo *sqlite3KeyInfoAlloc(sqlite3*,int,int);
@@ -288,13 +288,26 @@ int sqlite3_db_status(
    case SQLITE_DBSTATUS_SCHEMA_USED: {
      int i;                      /* Used to iterate through schemas */
      int nByte = 0;              /* Used to accumulate return value */
+      int bReleaseSchema;

      sqlite3BtreeEnterAll(db);
+      bReleaseSchema = sqlite3LockReusableSchema(db);
      db->pnBytesFreed = &nByte;
      assert( db->lookaside.pEnd==db->lookaside.pTrueEnd );
      db->lookaside.pEnd = db->lookaside.pStart;
      for(i=0; i<db->nDb; i++){
-        Schema *pSchema = db->aDb[i].pSchema;
+        Schema *pSchema;
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+        int bUnload = 0;
+        int nUsed = nByte;
+        if( db->aDb[i].pSPool ){
+          char *zDummy = 0;
+          rc = sqlite3SchemaLoad(db, i, &bUnload, &zDummy);
+          sqlite3_free(zDummy);
+          if( rc ) break;
+        }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+        pSchema = db->aDb[i].pSchema;
        if( ALWAYS(pSchema!=0) ){
          HashElem *p;

@@ -316,7 +329,14 @@ int sqlite3_db_status(
            sqlite3DeleteTable(db, (Table *)sqliteHashData(p));
          }
        }
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+        if( db->aDb[i].pSPool ){
+          if( bUnload ) sqlite3SchemaRelease(db, i);
+          sqlite3SchemaAdjustUsed(db, i, nUsed, &nByte);
+        }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
      }
+      sqlite3UnlockReusableSchema(db, bReleaseSchema);
      db->pnBytesFreed = 0;
      db->lookaside.pEnd = db->lookaside.pTrueEnd;
      sqlite3BtreeLeaveAll(db);
@@ -3727,6 +3727,9 @@ static int sqliteCmdUsage(
    "HANDLE ?FILENAME? ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN?"
    " ?-nofollow BOOLEAN?"
    " ?-nomutex BOOLEAN? ?-fullmutex BOOLEAN? ?-uri BOOLEAN?"
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    " ?-shared-schema BOOLEAN?"
+#endif
  );
  return TCL_ERROR;
 }
@@ -3858,6 +3861,16 @@ static int SQLITE_TCLAPI DbMain(
      }else{
        flags &= ~SQLITE_OPEN_URI;
      }
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    }else if( strcmp(zArg, "-shared-schema")==0 ){
+      int b;
+      if( Tcl_GetBooleanFromObj(interp, objv[i], &b) ) return TCL_ERROR;
+      if( b ){
+        flags |= SQLITE_OPEN_SHARED_SCHEMA;
+      }else{
+        flags &= ~SQLITE_OPEN_SHARED_SCHEMA;
+      }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
    }else if( strcmp(zArg, "-translatefilename")==0 ){
      if( Tcl_GetBooleanFromObj(interp, objv[i], &bTranslateFileName) ){
        return TCL_ERROR;
@@ -771,6 +771,12 @@ Tcl_SetVar2(interp, "sqlite_options", "mergesort", "1", TCL_GLOBAL_ONLY);
  Tcl_SetVar2(interp, "sqlite_options", "windowfunc", "1", TCL_GLOBAL_ONLY);
 #endif

+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  Tcl_SetVar2(interp, "sqlite_options", "sharedschema", "1", TCL_GLOBAL_ONLY);
+#else
+  Tcl_SetVar2(interp, "sqlite_options", "sharedschema", "0", TCL_GLOBAL_ONLY);
+#endif
+
 #define LINKVAR(x) { \
    static const int cv_ ## x = SQLITE_ ## x; \
    Tcl_LinkVar(interp, "SQLITE_" #x, (char *)&(cv_ ## x), \
@@ -0,0 +1,282 @@
+/*
+** 2006 June 10
+**
+** 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.
+**
+*************************************************************************
+** Code for testing the virtual table interfaces.  This code
+** is not included in the SQLite library.  It is used for automated
+** testing of the SQLite library.
+*/
+
+/*
+** None of this works unless we have virtual tables.
+*/
+#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_TEST)
+
+#include <tcl.h>
+
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+
+#include "sqliteInt.h"
+
+/* The code in this file defines a sqlite3 virtual-table module with
+** the following schema.
+*/
+#define SCHEMAPOOL_SCHEMA \
+"CREATE TABLE x("         \
+"  cksum   INTEGER, "     \
+"  nref    INTEGER, "     \
+"  nschema INTEGER, "     \
+"  ndelete INTEGER  "     \
+")"
+
+#define SCHEMAPOOL_NFIELD 4
+
+typedef struct schemapool_vtab schemapool_vtab;
+typedef struct schemapool_cursor schemapool_cursor;
+
+/* A schema table object */
+struct schemapool_vtab {
+  sqlite3_vtab base;
+};
+
+/* A schema table cursor object */
+struct schemapool_cursor {
+  sqlite3_vtab_cursor base;
+  sqlite3_int64 *aData;
+  int iRow;
+  int nRow;
+};
+
+/*
+** Table destructor for the schema module.
+*/
+static int schemaPoolDestroy(sqlite3_vtab *pVtab){
+  sqlite3_free(pVtab);
+  return 0;
+}
+
+/*
+** Table constructor for the schema module.
+*/
+static int schemaPoolCreate(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  int rc = SQLITE_NOMEM;
+  schemapool_vtab *pVtab = sqlite3_malloc(sizeof(schemapool_vtab));
+  if( pVtab ){
+    memset(pVtab, 0, sizeof(schemapool_vtab));
+    rc = sqlite3_declare_vtab(db, SCHEMAPOOL_SCHEMA);
+    if( rc!=SQLITE_OK ){
+      sqlite3_free(pVtab);
+      pVtab = 0;
+    }
+  }
+  *ppVtab = (sqlite3_vtab *)pVtab;
+  return rc;
+}
+
+/*
+** Open a new cursor on the schema table.
+*/
+static int schemaPoolOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+  int rc = SQLITE_NOMEM;
+  schemapool_cursor *pCur;
+  pCur = sqlite3_malloc(sizeof(schemapool_cursor));
+  if( pCur ){
+    memset(pCur, 0, sizeof(schemapool_cursor));
+    *ppCursor = (sqlite3_vtab_cursor*)pCur;
+    rc = SQLITE_OK;
+  }
+  return rc;
+}
+
+/*
+** Close a schema table cursor.
+*/
+static int schemaPoolClose(sqlite3_vtab_cursor *cur){
+  schemapool_cursor *pCur = (schemapool_cursor*)cur;
+  sqlite3_free(pCur->aData);
+  sqlite3_free(pCur);
+  return SQLITE_OK;
+}
+
+/*
+** Retrieve a column of data.
+*/
+static int schemaPoolColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
+  schemapool_cursor *pCur = (schemapool_cursor*)cur;
+  assert( i==0 || i==1 || i==2 || i==3 );
+  sqlite3_result_int64(ctx, pCur->aData[pCur->iRow*SCHEMAPOOL_NFIELD + i]);
+  return SQLITE_OK;
+}
+
+/*
+** Retrieve the current rowid.
+*/
+static int schemaPoolRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  schemapool_cursor *pCur = (schemapool_cursor*)cur;
+  *pRowid = pCur->iRow + 1;
+  return SQLITE_OK;
+}
+
+static int schemaPoolEof(sqlite3_vtab_cursor *cur){
+  schemapool_cursor *pCur = (schemapool_cursor*)cur;
+  return pCur->iRow>=pCur->nRow;
+}
+
+/*
+** Advance the cursor to the next row.
+*/
+static int schemaPoolNext(sqlite3_vtab_cursor *cur){
+  schemapool_cursor *pCur = (schemapool_cursor*)cur;
+  pCur->iRow++;
+  return SQLITE_OK;
+}
+
+struct SchemaPool {
+  int nRef;                       /* Number of pointers to this object */
+  int nDelete;                    /* Schema objects deleted by ReleaseAll() */
+  u64 cksum;                      /* Checksum for this Schema contents */
+  Schema *pSchema;                /* Linked list of Schema objects */
+  Schema sSchema;                 /* The single dummy schema object */
+  SchemaPool *pNext;              /* Next element in schemaPoolList */
+};
+extern SchemaPool *sqlite3SchemaPoolList(void);
+
+/*
+** Reset a schemaPool table cursor.
+*/
+static int schemaPoolFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  SchemaPool *pSPool;
+  schemapool_cursor *pCur = (schemapool_cursor*)pVtabCursor;
+
+  sqlite3_free(pCur->aData);
+  pCur->aData = 0;
+  pCur->nRow = 0;
+  pCur->iRow = 0;
+
+  for(pSPool = sqlite3SchemaPoolList(); pSPool; pSPool=pSPool->pNext){
+    pCur->nRow++;
+  }
+
+  if( pCur->nRow ){
+    int iRow = 0;
+    int nByte = SCHEMAPOOL_NFIELD * pCur->nRow * sizeof(i64);
+    pCur->aData = (i64*)sqlite3_malloc(nByte);
+    if( pCur->aData==0 ) return SQLITE_NOMEM;
+    for(pSPool = sqlite3SchemaPoolList(); pSPool; pSPool=pSPool->pNext){
+      Schema *p;
+      i64 nSchema = 0;
+      for(p=pSPool->pSchema; p; p=p->pNext){
+        nSchema++;
+      }
+      pCur->aData[0 + iRow*SCHEMAPOOL_NFIELD] = pSPool->cksum;
+      pCur->aData[1 + iRow*SCHEMAPOOL_NFIELD] = (i64)pSPool->nRef;
+      pCur->aData[2 + iRow*SCHEMAPOOL_NFIELD] = nSchema;
+      pCur->aData[3 + iRow*SCHEMAPOOL_NFIELD] = (i64)pSPool->nDelete;
+      iRow++;
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Analyse the WHERE condition.
+*/
+static int schemaPoolBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
+  return SQLITE_OK;
+}
+
+/*
+** A virtual table module that merely echos method calls into TCL
+** variables.
+*/
+static sqlite3_module schemaPoolModule = {
+  0,                           /* iVersion */
+  schemaPoolCreate,
+  schemaPoolCreate,
+  schemaPoolBestIndex,
+  schemaPoolDestroy,
+  schemaPoolDestroy,
+  schemaPoolOpen,              /* xOpen - open a cursor */
+  schemaPoolClose,             /* xClose - close a cursor */
+  schemaPoolFilter,            /* xFilter - configure scan constraints */
+  schemaPoolNext,              /* xNext - advance a cursor */
+  schemaPoolEof,               /* xEof */
+  schemaPoolColumn,            /* xColumn - read data */
+  schemaPoolRowid,             /* xRowid - read data */
+  0,                           /* xUpdate */
+  0,                           /* xBegin */
+  0,                           /* xSync */
+  0,                           /* xCommit */
+  0,                           /* xRollback */
+  0,                           /* xFindMethod */
+  0,                           /* xRename */
+};
+
+/*
+** Decode a pointer to an sqlite3 object.
+*/
+extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
+
+/*
+** Register the schema virtual table module.
+*/
+static int SQLITE_TCLAPI register_schemapool_module(
+  ClientData clientData, /* Not used */
+  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
+  int objc,              /* Number of arguments */
+  Tcl_Obj *CONST objv[]  /* Command arguments */
+){
+  sqlite3 *db;
+  if( objc!=2 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB");
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  sqlite3_create_module(db, "schemapool", &schemaPoolModule, 0);
+#endif
+  return TCL_OK;
+}
+
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_TEST) */
+
+/*
+** Register commands with the TCL interpreter.
+*/
+int Sqlitetestschemapool_Init(Tcl_Interp *interp){
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  static struct {
+     char *zName;
+     Tcl_ObjCmdProc *xProc;
+     void *clientData;
+  } aObjCmd[] = {
+     { "register_schemapool_module", register_schemapool_module, 0 },
+  };
+  int i;
+  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
+    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, 
+        aObjCmd[i].xProc, aObjCmd[i].clientData, 0);
+  }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+  return TCL_OK;
+}
+
@@ -76,6 +76,7 @@ const char *sqlite3TestInit(Tcl_Interp *interp){
  extern int Sqlitetest_malloc_Init(Tcl_Interp*);
  extern int Sqlitetest_mutex_Init(Tcl_Interp*);
  extern int Sqlitetestschema_Init(Tcl_Interp*);
+  extern int Sqlitetestschemapool_Init(Tcl_Interp*);
  extern int Sqlitetestsse_Init(Tcl_Interp*);
  extern int Sqlitetesttclvar_Init(Tcl_Interp*);
  extern int Sqlitetestfs_Init(Tcl_Interp*);
@@ -147,6 +148,7 @@ const char *sqlite3TestInit(Tcl_Interp *interp){
  Sqlitetest_malloc_Init(interp);
  Sqlitetest_mutex_Init(interp);
  Sqlitetestschema_Init(interp);
+  Sqlitetestschemapool_Init(interp);
  Sqlitetesttclvar_Init(interp);
  Sqlitetestfs_Init(interp);
  SqlitetestThread_Init(interp);
@@ -52,13 +52,34 @@ Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
  Trigger *pList;           /* List of triggers to return */
  HashElem *p;              /* Loop variable for TEMP triggers */

+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  char *zSchema = 0;
+  sqlite3 *db = pParse->db;
+  if( IsSharedSchema(db) ){
+    zSchema = db->aDb[sqlite3SchemaToIndex(db, pTab->pSchema)].zDbSName;
+  }
+#endif
+
  assert( pParse->disableTriggers==0 );
  pTmpSchema = pParse->db->aDb[1].pSchema;
  p = sqliteHashFirst(&pTmpSchema->trigHash);
  pList = pTab->pTrigger;
  while( p ){
    Trigger *pTrig = (Trigger *)sqliteHashData(p);
-    if( pTrig->pTabSchema==pTab->pSchema
+
+    int bSchemaMatch;
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    if( zSchema ){
+      /* Shared-schema */
+      bSchemaMatch = (0==sqlite3StrICmp(pTrig->zTabSchema, zSchema));
+    }else
+#endif
+    {
+      /* Non-shared-schema */
+      bSchemaMatch = (pTrig->pTabSchema==pTab->pSchema);
+    }
+
+    if( bSchemaMatch
     && pTrig->table
     && 0==sqlite3StrICmp(pTrig->table, pTab->zName)
     && (pTrig->pTabSchema!=pTmpSchema || pTrig->bReturning)
@@ -68,7 +89,7 @@ Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
    }else if( pTrig->op==TK_RETURNING ){
 #ifndef SQLITE_OMIT_VIRTUALTABLE
      assert( pParse->db->pVtabCtx==0 );
-#endif
+#endif 
      assert( pParse->bReturning );
      assert( &(pParse->u1.pReturning->retTrig) == pTrig );
      pTrig->table = pTab->zName;
@@ -259,6 +280,12 @@ void sqlite3BeginTrigger(
  pTrigger->zName = zName;
  zName = 0;
  pTrigger->table = sqlite3DbStrDup(db, pTableName->a[0].zName);
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  if( IsSharedSchema(db) && iDb==1 ){
+    int iTabDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    pTrigger->zTabSchema = sqlite3DbStrDup(db, db->aDb[iTabDb].zDbSName);
+  }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
  pTrigger->pSchema = db->aDb[iDb].pSchema;
  pTrigger->pTabSchema = pTab->pSchema;
  pTrigger->op = (u8)op;
@@ -382,7 +409,7 @@ void sqlite3FinishTrigger(
       pTrig->table, z);
    sqlite3DbFree(db, z);
    sqlite3ChangeCookie(pParse, iDb);
-    sqlite3VdbeAddParseSchemaOp(v, iDb,
+    sqlite3VdbeAddParseSchemaOp(pParse, iDb,
        sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName), 0);
  }

@@ -601,6 +628,9 @@ void sqlite3DeleteTrigger(sqlite3 *db, Trigger *pTrigger){
  sqlite3DeleteTriggerStep(db, pTrigger->step_list);
  sqlite3DbFree(db, pTrigger->zName);
  sqlite3DbFree(db, pTrigger->table);
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  sqlite3DbFree(db, pTrigger->zTabSchema);
+#endif
  sqlite3ExprDelete(db, pTrigger->pWhen);
  sqlite3IdListDelete(db, pTrigger->pColumns);
  sqlite3DbFree(db, pTrigger);
@@ -672,6 +702,7 @@ void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){

  iDb = sqlite3SchemaToIndex(pParse->db, pTrigger->pSchema);
  assert( iDb>=0 && iDb<db->nDb );
+  sqlite3SchemaWritable(pParse, iDb);
  pTable = tableOfTrigger(pTrigger);
  assert( (pTable && pTable->pSchema==pTrigger->pSchema) || iDb==1 );
 #ifndef SQLITE_OMIT_AUTHORIZATION
@@ -1164,7 +1195,9 @@ static TriggerPrg *codeRowTrigger(
  int iEndTrigger = 0;        /* Label to jump to if WHEN is false */
  Parse sSubParse;            /* Parse context for sub-vdbe */

-  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
+  assert( pTrigger->zName==0 || IsSharedSchema(pParse->db)
+      || pTab==tableOfTrigger(pTrigger)
+  );
  assert( pTop->pVdbe );

  /* Allocate the TriggerPrg and SubProgram objects. To ensure that they
@@ -1271,7 +1304,9 @@ static TriggerPrg *getRowTrigger(
  Parse *pRoot = sqlite3ParseToplevel(pParse);
  TriggerPrg *pPrg;

-  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
+  assert( pTrigger->zName==0 || IsSharedSchema(pParse->db)
+      || pTab==tableOfTrigger(pTrigger) 
+  );

  /* It may be that this trigger has already been coded (or is in the
  ** process of being coded). If this is the case, then an entry with
@@ -1025,29 +1025,29 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
    double rr[2];
    rr[0] = r;
    rr[1] = 0.0;
-    if( rr[0]>1.84e+19 ){
-      while( rr[0]>1.84e+119 ){
+    if( rr[0]>9.223372036854774784e+18 ){
+      while( rr[0]>9.223372036854774784e+118 ){
        exp += 100;
        dekkerMul2(rr, 1.0e-100, -1.99918998026028836196e-117);
      }
-      while( rr[0]>1.84e+29 ){
+      while( rr[0]>9.223372036854774784e+28 ){
        exp += 10;
        dekkerMul2(rr, 1.0e-10, -3.6432197315497741579e-27);
      }
-      while( rr[0]>1.84e+19 ){
+      while( rr[0]>9.223372036854774784e+18 ){
        exp += 1;
        dekkerMul2(rr, 1.0e-01, -5.5511151231257827021e-18);
      }
    }else{
-      while( rr[0]<1.84e-82  ){
+      while( rr[0]<9.223372036854774784e-83  ){
        exp -= 100;
        dekkerMul2(rr, 1.0e+100, -1.5902891109759918046e+83);
      }
-      while( rr[0]<1.84e+08  ){
+      while( rr[0]<9.223372036854774784e+07  ){
        exp -= 10;
        dekkerMul2(rr, 1.0e+10, 0.0);
      }
-      while( rr[0]<1.84e+18  ){
+      while( rr[0]<9.22337203685477478e+17  ){
        exp -= 1;
        dekkerMul2(rr, 1.0e+01, 0.0);
      }
@@ -125,6 +125,7 @@ void sqlite3Vacuum(Parse *pParse, Token *pNm, Expr *pInto){
  }
  if( iDb!=1 ){
    int iIntoReg = 0;
+    sqlite3SchemaWritable(pParse, iDb);
    if( pInto && sqlite3ResolveSelfReference(pParse,0,0,pInto,0)==0 ){
      iIntoReg = ++pParse->nMem;
      sqlite3ExprCode(pParse, pInto, iIntoReg);
@@ -4065,13 +4065,6 @@ case OP_Transaction: {
   && pOp->p5
   && (iMeta!=pOp->p3 || pDb->pSchema->iGeneration!=pOp->p4.i)
  ){
-    /*
-    ** IMPLEMENTATION-OF: R-03189-51135 As each SQL statement runs, the schema
-    ** version is checked to ensure that the schema has not changed since the
-    ** SQL statement was prepared.
-    */
-    sqlite3DbFree(db, p->zErrMsg);
-    p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
    /* If the schema-cookie from the database file matches the cookie
    ** stored with the in-memory representation of the schema, do
    ** not reload the schema from the database file.
@@ -4088,6 +4081,13 @@ case OP_Transaction: {
    if( db->aDb[pOp->p1].pSchema->schema_cookie!=iMeta ){
      sqlite3ResetOneSchema(db, pOp->p1);
    }
+    /*
+    ** IMPLEMENTATION-OF: R-03189-51135 As each SQL statement runs, the schema
+    ** version is checked to ensure that the schema has not changed since the
+    ** SQL statement was prepared.
+    */
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
    p->expired = 1;
    rc = SQLITE_SCHEMA;

@@ -228,7 +228,7 @@ VdbeOp *sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp,int iLineno);
 #else
 # define sqlite3ExplainBreakpoint(A,B) /*no-op*/
 #endif
-void sqlite3VdbeAddParseSchemaOp(Vdbe*, int, char*, u16);
+void sqlite3VdbeAddParseSchemaOp(Parse*,int,char*,u16);
 void sqlite3VdbeChangeOpcode(Vdbe*, int addr, u8);
 void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
 void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
@@ -560,8 +560,10 @@ void sqlite3VdbeExplainPop(Parse *pParse){
 ** The zWhere string must have been obtained from sqlite3_malloc().
 ** This routine will take ownership of the allocated memory.
 */
-void sqlite3VdbeAddParseSchemaOp(Vdbe *p, int iDb, char *zWhere, u16 p5){
+void sqlite3VdbeAddParseSchemaOp(Parse *pParse, int iDb, char *zWhere, u16 p5){
+  Vdbe *p = pParse->pVdbe;
  int j;
+  sqlite3SchemaWritable(pParse, iDb);
  sqlite3VdbeAddOp4(p, OP_ParseSchema, iDb, 0, 0, zWhere, P4_DYNAMIC);
  sqlite3VdbeChangeP5(p, p5);
  for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
@@ -59,8 +59,7 @@ static int blobSeekToRow(Incrblob *p, sqlite3_int64 iRow, char **pzErr){
  /* Set the value of register r[1] in the SQL statement to integer iRow. 
  ** This is done directly as a performance optimization
  */
-  v->aMem[1].flags = MEM_Int;
-  v->aMem[1].u.i = iRow;
+  sqlite3VdbeMemSetInt64(&v->aMem[1], iRow);

  /* If the statement has been run before (and is paused at the OP_ResultRow)
  ** then back it up to the point where it does the OP_NotExists.  This could
@@ -135,6 +134,7 @@ int sqlite3_blob_open(
  Table *pTab;
  Incrblob *pBlob = 0;
  Parse sParse;
+  int bUnlock;            /* True to unlock reusable schemas before returning */

 #ifdef SQLITE_ENABLE_API_ARMOR
  if( ppBlob==0 ){
@@ -151,6 +151,7 @@ int sqlite3_blob_open(

  sqlite3_mutex_enter(db->mutex);

+  bUnlock = sqlite3LockReusableSchema(db);
  pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
  while(1){
    sqlite3ParseObjectInit(&sParse,db);
@@ -336,6 +337,7 @@ int sqlite3_blob_open(
  }

 blob_open_out:
+  sqlite3UnlockReusableSchema(db, bUnlock);
  if( rc==SQLITE_OK && db->mallocFailed==0 ){
    *ppBlob = (sqlite3_blob *)pBlob;
  }else{
@@ -192,6 +192,24 @@ void sqlite3VtabLock(VTable *pVTab){
 VTable *sqlite3GetVTable(sqlite3 *db, Table *pTab){
  VTable *pVtab;
  assert( IsVirtual(pTab) );
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  if( IsSharedSchema(db) ){
+    int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    if( iDb!=1 ){
+      VTable **pp;
+      for(pp=&db->aDb[iDb].pVTable; *pp; pp=&(*pp)->pNext){
+        if( sqlite3StrICmp(pTab->zName, (*pp)->zName)==0 ) break;
+      }
+      pVtab = *pp;
+      if( pVtab && pTab->nCol<=0 ){
+        *pp = pVtab->pNext;
+        sqlite3VtabUnlock(pVtab);
+        pVtab = 0;
+      }
+      return pVtab;
+    }
+  }
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
  for(pVtab=pTab->u.vtab.p; pVtab && pVtab->db!=db; pVtab=pVtab->pNext);
  return pVtab;
 }
@@ -500,7 +518,7 @@ void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){

    sqlite3VdbeAddOp0(v, OP_Expire);
    zWhere = sqlite3MPrintf(db, "name=%Q AND sql=%Q", pTab->zName, zStmt);
-    sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere, 0);
+    sqlite3VdbeAddParseSchemaOp(pParse, iDb, zWhere, 0);
    sqlite3DbFree(db, zStmt);

    iReg = ++pParse->nMem;
@@ -570,6 +588,7 @@ static int vtabCallConstructor(
  char *zModuleName;
  int iDb;
  VtabCtx *pCtx;
+  int nByte;                      /* Bytes of space to allocate */

  assert( IsVirtual(pTab) );
  azArg = (const char *const*)pTab->u.vtab.azArg;
@@ -589,7 +608,11 @@ static int vtabCallConstructor(
    return SQLITE_NOMEM_BKPT;
  }

-  pVTable = sqlite3MallocZero(sizeof(VTable));
+  nByte = sizeof(VTable);
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  nByte += sqlite3Strlen30(pTab->zName) + 1;
+#endif
+  pVTable = (VTable*)sqlite3MallocZero(nByte);
  if( !pVTable ){
    sqlite3OomFault(db);
    sqlite3DbFree(db, zModuleName);
@@ -597,6 +620,10 @@ static int vtabCallConstructor(
  }
  pVTable->db = db;
  pVTable->pMod = pMod;
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+  pVTable->zName = (char*)&pVTable[1];
+  memcpy(pVTable->zName, pTab->zName, nByte-sizeof(VTable));
+#endif
  pVTable->eVtabRisk = SQLITE_VTABRISK_Normal;

  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
@@ -641,12 +668,23 @@ static int vtabCallConstructor(
      int iCol;
      u16 oooHidden = 0;
      /* If everything went according to plan, link the new VTable structure
-      ** into the linked list headed by pTab->u.vtab.p. Then loop through the
-      ** columns of the table to see if any of them contain the token "hidden".
-      ** If so, set the Column COLFLAG_HIDDEN flag and remove the token from
-      ** the type string.  */
-      pVTable->pNext = pTab->u.vtab.p;
-      pTab->u.vtab.p = pVTable;
+      ** into the linked list headed by pTab->u.vtab.p. Or, if this is a
+      ** reusable schema, into the linked list headed by Db.pVTable.
+      **
+      ** Then loop through the columns of the table to see if any of them
+      ** contain the token "hidden". If so, set the Column COLFLAG_HIDDEN flag
+      ** and remove the token from the type string.  */
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+      if( IsSharedSchema(db) && iDb!=1 ){
+        pVTable->pNext = db->aDb[iDb].pVTable;
+        db->aDb[iDb].pVTable = pVTable;
+      }else
+#endif /* ifdef SQLITE_ENABLE_SHARED_SCHEMA */
+      {
+        assert( IsVirtual(pTab) );
+        pVTable->pNext = pTab->u.vtab.p;
+        pTab->u.vtab.p = pVTable;
+      }

      for(iCol=0; iCol<pTab->nCol; iCol++){
        char *zType = sqlite3ColumnType(&pTab->aCol[iCol], "");
@@ -701,6 +739,7 @@ int sqlite3VtabCallConnect(Parse *pParse, Table *pTab){
  assert( pTab );
  assert( IsVirtual(pTab) );
  if( sqlite3GetVTable(db, pTab) ){
+    assert( !IsVirtual(pTab) || pTab->nCol>0 );
    return SQLITE_OK;
  }

@@ -1493,7 +1493,7 @@ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
      sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg);
    }
  }
-  if( pTab->u.vtab.p->bAllSchemas ){
+  if( pTab->u.vtab.p && pTab->u.vtab.p->bAllSchemas ){
    sqlite3VtabUsesAllSchemas(pParse);
  }
  sqlite3_free(pVtab->zErrMsg);
@@ -1545,4 +1545,12 @@ do_catchsql_test func-37.120 {
  SELECT sum(x) FROM c;
 } {1 {integer overflow}}

+# 2023-08-28 forum post https://sqlite.org/forum/forumpost/1c06ddcacc86032a
+# Incorrect handling of infinity by SUM().
+#
+do_execsql_test func-38.100 {
+  WITH t1(x) AS (VALUES(9e+999)) SELECT sum(x), avg(x), total(x) FROM t1;
+  WITH t1(x) AS (VALUES(-9e+999)) SELECT sum(x), avg(x), total(x) FROM t1;
+} {Inf Inf Inf -Inf -Inf -Inf}
+
 finish_test
@@ -1013,8 +1013,31 @@ do_execsql_test json101-21.27 {
  SELECT json_group_object(x,y) FROM c;
 } {{{"a":1,"b":2.0,"c":null,:"three","e":"four"}}}

-
-
+# 2023-10-09 https://sqlite.org/forum/forumpost/b25edc1d46
+# UAF due to JSON cache overflow
+#
+do_execsql_test json101-22.1 {
+  SELECT json_set(
+    '{}',
+    '$.a', json('1'),
+    '$.a', json('2'),
+    '$.b', json('3'),
+    '$.b', json('4'),
+    '$.c', json('5'),
+    '$.c', json('6')
+  );
+} {{{"a":2,"b":4,"c":6}}}
+do_execsql_test json101-22.2 {
+  SELECT json_replace(
+    '{"a":7,"b":8,"c":9}',
+    '$.a', json('1'),
+    '$.a', json('2'),
+    '$.b', json('3'),
+    '$.b', json('4'),
+    '$.c', json('5'),
+    '$.c', json('6')
+  );
+} {{{"a":2,"b":4,"c":6}}}


 finish_test
@@ -48,6 +48,9 @@ do_execsql_test json102-180 {
 do_execsql_test json102-190 {
  SELECT json_array_length('[1,2,3,4]');
 } {{4}}
+do_execsql_test json102-191 {
+  SELECT json_array_length( json_remove('[1,2,3,4]','$[2]') );
+} {{3}}
 do_execsql_test json102-200 {
  SELECT json_array_length('[1,2,3,4]', '$');
 } {{4}}
@@ -0,0 +1,394 @@
+# 2017 August 9
+#
+# 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 $testdir/tester.tcl
+set testprefix reuse1
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+forcedelete test.db2
+sqlite3 db2 test.db2
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE, z);
+  CREATE INDEX i1 ON t1(z);
+  PRAGMA schema_version;
+} {2}
+
+do_execsql_test -db db2 1.1 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE, z);
+  CREATE INDEX i1 ON t1(z);
+  PRAGMA schema_version;
+} {2}
+
+do_test 1.2 {
+  db close
+  db2 close
+  sqlite3 db2 test.db2 -shared-schema 1
+  sqlite3 db  test.db -shared-schema 1
+} {}
+
+do_execsql_test -db db2 1.3.1 {
+  INSERT INTO t1 VALUES(1, 2, 3);
+  INSERT INTO t1 VALUES(4, 5, 6);
+}
+
+do_execsql_test 1.3.2 {
+  SELECT * FROM t1;
+  PRAGMA integrity_check;
+} {ok}
+
+do_execsql_test -db db2 1.3.3 {
+  SELECT * FROM t1;
+  PRAGMA integrity_check;
+} {1 2 3 4 5 6 ok}
+
+sqlite3 db3 test.db2
+do_execsql_test -db db3 1.4.1 {
+  ALTER TABLE t1 ADD COLUMN a;
+}
+do_execsql_test -db db2 1.4.2 {
+  SELECT * FROM t1;
+} {1 2 3 {} 4 5 6 {}}
+do_execsql_test 1.4.3 {
+  SELECT * FROM t1;
+} {}
+
+db3 close
+sqlite3 db3 test.db
+do_execsql_test -db db3 1.5.0 {
+  CREATE TRIGGER tr1 AFTER INSERT ON t1 BEGIN
+    SELECT 1, 2, 3;
+  END;
+}
+
+# Check that the schema cannot be modified if the db was opened with
+# SQLITE_OPEN_REUSE_SCHEMA.
+#
+foreach {tn sql} {
+  1  { CREATE TABLE t2(x, y) }
+  2  { CREATE INDEX i2 ON t1(z) }
+  3  { CREATE VIEW v2 AS SELECT * FROM t2 }
+  4  { ALTER TABLE t1 RENAME TO t3 }
+  5  { ALTER TABLE t1 ADD COLUMN xyz }
+  6  { VACUUM }
+  7  { DROP INDEX i1 }
+  8  { DROP TABLE t1 }
+  9  { DROP TRIGGER tr1 }
+  10 { ANALYZE }
+  11 { ALTER TABLE t1 RENAME z TO zzz }
+} {
+  do_catchsql_test 1.5.$tn $sql {1 {attempt to modify read-only schema}}
+}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+forcedelete test.db2
+ifcapable fts5 {
+  do_execsql_test 2.0 {
+    CREATE VIRTUAL TABLE ft USING fts5(a);
+    INSERT INTO ft VALUES('one'), ('two'), ('three');
+    ATTACH 'test.db2' AS aux;
+    CREATE VIRTUAL TABLE aux.ft USING fts5(a);
+    INSERT INTO aux.ft VALUES('aux1'), ('aux2'), ('aux3');
+  }
+
+  db close
+  sqlite3 db  test.db -shared-schema 1
+
+  do_execsql_test 2.1 {
+    ATTACH 'test.db2' AS aux;
+    SELECT * FROM main.ft;
+  } {one two three}
+
+breakpoint
+  do_execsql_test 2.2 {
+    SELECT * FROM aux.ft;
+  } {aux1 aux2 aux3}
+
+  do_execsql_test 2.2 {
+    SELECT * FROM aux.ft_content;
+  } {1 aux1 2 aux2 3 aux3}
+}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+forcedelete test.db2
+do_execsql_test 3.0 {
+  CREATE TABLE t1(a PRIMARY KEY, b, c);
+  CREATE VIEW v1 AS SELECT * FROM t1;
+  CREATE TRIGGER v1_ins INSTEAD OF INSERT ON v1 BEGIN
+    INSERT INTO t1 VALUES(new.a, new.b, new.c);
+  END;
+  CREATE TRIGGER v1_del INSTEAD OF DELETE ON v1 BEGIN
+    DELETE FROM t1 WHERE a=old.a;
+  END;
+  CREATE TRIGGER v1_up INSTEAD OF UPDATE ON v1 BEGIN
+    UPDATE t1 SET a=new.a, b=new.b, c=new.c WHERE a=old.a;
+  END;
+}
+forcecopy test.db test.db2
+
+do_test 3.1 {
+  sqlite3 db2 test.db2
+  execsql { INSERT INTO t1 VALUES(1, 2, 3) } db
+  execsql { INSERT INTO t1 VALUES(4, 5, 6) } db2
+  db2 close
+  execsql { ATTACH 'test.db2' AS aux; }
+} {}
+
+do_execsql_test 3.2 {
+  SELECT * FROM main.v1;
+} {1 2 3}
+
+do_execsql_test 3.3 {
+  SELECT * FROM aux.v1;
+} {4 5 6}
+
+db close
+sqlite3 db test.db -shared-schema 1
+
+do_execsql_test 3.4 { ATTACH 'test.db2' AS aux } {}
+do_execsql_test 3.5 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.6 { SELECT * FROM aux.v1  } {4 5 6}
+
+do_execsql_test 3.7.1 { INSERT INTO aux.t1 VALUES(8, 9, 10); }
+do_execsql_test 3.7.2 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.7.3 { SELECT * FROM aux.v1  } {4 5 6 8 9 10}
+
+do_execsql_test 3.8.1 { DELETE FROM aux.t1 WHERE b=5 }
+do_execsql_test 3.8.2 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.8.3 { SELECT * FROM aux.v1  } {8 9 10}
+
+do_execsql_test 3.9.1 { UPDATE aux.t1 SET b='abc' }
+do_execsql_test 3.9.2 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.9.3 { SELECT * FROM aux.v1  } {8 abc 10}
+
+do_execsql_test 3.10.1 { INSERT INTO aux.v1 VALUES(11, 12, 13) }
+do_execsql_test 3.10.2 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.10.3 { SELECT * FROM aux.v1  } {8 abc 10 11 12 13}
+
+do_execsql_test 3.11.1 { DELETE FROM aux.v1 WHERE b='abc' }
+do_execsql_test 3.11.2 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.11.3 { SELECT * FROM aux.v1  } {11 12 13}
+
+do_execsql_test 3.12.1 { UPDATE aux.v1 SET b='def' }
+do_execsql_test 3.12.2 { SELECT * FROM main.v1 } {1 2 3}
+do_execsql_test 3.12.3 { SELECT * FROM aux.v1  } {11 def 13}
+
+do_execsql_test 3.13.1 {
+  CREATE TEMP TRIGGER xyz AFTER INSERT ON aux.t1 BEGIN
+    INSERT INTO v1 VALUES(new.a, new.b, new.c);
+  END
+}
+do_execsql_test 3.13.2 {
+  INSERT INTO aux.v1 VALUES('x', 'y', 'z');
+}
+do_execsql_test 3.13.3 {
+  SELECT * FROM v1;
+} {1 2 3 x y z}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+forcedelete test.db2
+do_execsql_test 4.0 {
+  CREATE TABLE t1(a PRIMARY KEY, b, c UNIQUE);
+  CREATE TABLE del(a, b, c);
+  CREATE TRIGGER tr1 AFTER DELETE ON t1 BEGIN
+    INSERT INTO del VALUES(old.a, old.b, old.c);
+  END;
+}
+forcecopy test.db test.db2
+
+db close
+sqlite3 db test.db -shared-schema 1
+execsql { 
+  ATTACH 'test.db2' AS aux;
+  PRAGMA recursive_triggers = 1;
+}
+
+do_execsql_test 4.1 {
+  INSERT INTO main.t1 VALUES(1, 2, 3);
+  INSERT INTO aux.t1 VALUES(4, 5, 6);
+}
+
+do_execsql_test 4.2.1 {
+  INSERT OR REPLACE INTO aux.t1 VALUES('a', 'b', 6);
+  SELECT * FROM aux.t1;
+} {a b 6}
+do_execsql_test 4.2.2 { SELECT * FROM aux.del  } {4 5 6}
+do_execsql_test 4.2.3 { SELECT * FROM main.del } {}
+
+do_execsql_test 4.3.1 {
+  INSERT INTO aux.t1 VALUES('x', 'y', 'z');
+  UPDATE OR REPLACE aux.t1 SET c='z' WHERE a='a';
+} {}
+do_execsql_test 4.3.2 { SELECT * FROM aux.del  } {4 5 6 x y z}
+do_execsql_test 4.3.3 { SELECT * FROM main.del } {}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 5.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
+  CREATE TABLE t2(a INTEGER PRIMARY KEY, b, c);
+  CREATE INDEX i1 ON t1(b);
+  INSERT INTO t1 VALUES(1, 2, 3), (4, 5, 6);
+  ANALYZE;
+  PRAGMA writable_schema = 1;
+  DELETE FROM sqlite_stat1;
+}
+db close
+forcecopy test.db test.db2
+sqlite3 db test.db -shared-schema 1
+execsql { ATTACH 'test.db2' AS aux }
+
+foreach {tn sql} {
+  1 { CREATE TABLE t3(x) }
+  2 { DROP TABLE t2 }
+  3 { CREATE INDEX i2 ON t2(b) }
+  4 { DROP INDEX i1 }
+  5 { ALTER TABLE t1 ADD COLUMN d }
+  6 { ALTER TABLE t1 RENAME TO t3 }
+  7 { ALTER TABLE t1 RENAME c TO d }
+} {
+  do_catchsql_test 5.1.$tn $sql {1 {attempt to modify read-only schema}}
+}
+
+do_execsql_test 5.2.1 { ANALYZE aux.t1 } {}
+do_execsql_test 5.2.2 { SELECT * FROM aux.sqlite_stat1  } {t1 i1 {2 1}}
+do_execsql_test 5.2.3 { SELECT * FROM main.sqlite_stat1 } {}
+
+do_test 5.3.0 {
+  sqlite3 db2 test.db2
+  db2 eval { 
+    PRAGMA writable_schema = 1;
+    DELETE FROM sqlite_stat1;
+  }
+} {}
+
+do_execsql_test 5.3.1 { SELECT * FROM aux.sqlite_stat1  } {}
+do_execsql_test 5.3.2 { ANALYZE aux } {}
+do_execsql_test 5.3.3 { SELECT * FROM aux.sqlite_stat1  } {t1 i1 {2 1}}
+do_execsql_test 5.3.4 { SELECT * FROM main.sqlite_stat1 } {}
+
+#-------------------------------------------------------------------------
+# Attempting to run ANALYZE when the required sqlite_statXX functions
+# are missing is an error (because it would modify the database schema).
+#
+reset_db
+do_execsql_test 5.4 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
+  CREATE TABLE t2(a INTEGER PRIMARY KEY, b, c);
+  CREATE INDEX i1 ON t1(b);
+  INSERT INTO t1 VALUES(1, 2, 3), (4, 5, 6);
+}
+db close
+sqlite3 db test.db -shared-schema 1
+foreach {tn sql} {
+  1 { ANALYZE }
+  2 { ANALYZE t1 }
+  3 { ANALYZE i1 }
+  4 { ANALYZE main }
+  5 { ANALYZE main.t1 }
+  6 { ANALYZE main.i1 }
+} {
+  do_catchsql_test 5.4.$tn $sql {1 {attempt to modify read-only schema}}
+}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 6.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
+  CREATE VIEW v1 AS SELECT * FROM t1;
+}
+db close
+forcecopy test.db test.db2
+sqlite3 db test.db -shared-schema 1
+execsql { ATTACH 'test.db2' AS aux }
+
+do_execsql_test 6.1 {
+  INSERT INTO main.t1(a) VALUES(1), (2), (3);
+  INSERT INTO aux.t1(a) VALUES(4), (5), (6);
+  CREATE TEMP TABLE t2(i,t);
+  INSERT INTO t2 VALUES(2, 'two'), (5, 'five');
+}
+
+do_execsql_test 6.2 {
+  SELECT t FROM t2 WHERE i IN (SELECT a FROM aux.t1)
+} {five}
+do_execsql_test 6.3 {
+  SELECT t FROM t2 WHERE i IN (SELECT a FROM aux.v1)
+} {five}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 7.0 {
+  CREATE TABLE p1(a PRIMARY KEY, b);
+  CREATE TABLE p2(a PRIMARY KEY, b);
+  CREATE TABLE c1(x REFERENCES p1 ON UPDATE CASCADE ON DELETE CASCADE);
+}
+
+db close
+forcecopy test.db test.db2
+sqlite3 db test.db -shared-schema 1
+execsql { ATTACH 'test.db2' AS aux }
+
+do_execsql_test 7.1 {
+  INSERT INTO aux.p1 VALUES(1, 'one');
+  INSERT INTO aux.p1 VALUES(2, 'two');
+  PRAGMA foreign_keys = on;
+}
+
+do_execsql_test 7.2 {
+  INSERT INTO aux.c1 VALUES(2);
+}
+
+do_execsql_test 7.3.1 {
+  PRAGMA foreign_keys = off;
+  INSERT INTO main.p2 SELECT * FROM aux.p1;
+}
+do_execsql_test 7.3.2 {
+  SELECT * FROM main.p2;
+} {1 one 2 two}
+
+do_execsql_test 7.3.3 {
+  INSERT INTO aux.p2 VALUES(1, 2);
+}
+
+do_execsql_test 7.3.4 {
+  SELECT main.p2.a FROM main.p2, aux.p2;
+} {1 2}
+
+do_execsql_test 7.3.5 {
+  SELECT * FROM main.p2, aux.p2;
+} {1 one 1 2   2 two 1 2}
+
+do_execsql_test 7.4 {
+  SELECT count(*) FROM aux.p2;
+} {1}
+
+
+finish_test
+
+
@@ -0,0 +1,336 @@
+# 2017 August 9
+#
+# 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 reuse2
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE, z);
+  CREATE INDEX i1 ON t1(z);
+  PRAGMA schema_version;
+} {2}
+
+do_test 1.2 {
+  catch { db close }
+  catch { db2 close }
+  sqlite3 db2 test.db -shared-schema 1
+  sqlite3 db  test.db -shared-schema 1
+} {}
+
+do_execsql_test -db db2 1.3.1 {
+  INSERT INTO t1 VALUES(1, 2, 3);
+}
+
+do_execsql_test -db db2 1.3.2 {
+  INSERT INTO t1 VALUES(4, 5, 6);
+}
+
+do_execsql_test 1.3.3 {
+  SELECT * FROM t1;
+} {1 2 3 4 5 6}
+
+#--------------------------------------------------------------------------
+reset_db
+ifcapable fts5 {
+  do_execsql_test 2.0 {
+    CREATE VIRTUAL TABLE ft USING fts5(c);
+    INSERT INTO ft VALUES('one two three');
+  }
+  db close
+  sqlite3 db test.db -shared-schema 1
+
+  do_execsql_test 2.1 {
+    SELECT * FROM ft
+  } {{one two three}}
+}
+
+#--------------------------------------------------------------------------
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE, z);
+  CREATE INDEX i1 ON t1(z);
+  PRAGMA schema_version;
+} {2}
+
+do_test 3.1 {
+  sqlite3 db1 test.db -shared-schema 1
+  sqlite3 db2 test.db -shared-schema 1
+} {}
+
+do_execsql_test -db db1 3.2.1 { SELECT * FROM t1 }
+do_execsql_test -db db2 3.2.2 { SELECT * FROM t1 }
+
+register_schemapool_module db
+do_execsql_test 3.3 { 
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=2 nschema=1 ndelete=0}
+
+sqlite3 db3 test.db -shared-schema 1
+register_schemapool_module db3
+
+do_execsql_test 3.5 { 
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=2 nschema=1 ndelete=0}
+
+do_execsql_test -db db3 3.6 { 
+  SELECT * FROM t1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=3 nschema=1 ndelete=0}
+
+do_execsql_test 3.7 { 
+  CREATE TABLE t2(x);
+}
+
+do_execsql_test 3.8 { 
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=3 nschema=1 ndelete=0}
+
+do_execsql_test -db db1 3.9.1 { SELECT * FROM t1 }
+do_execsql_test 3.9.2 { 
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=1 nschema=1 ndelete=0 nref=2 nschema=1 ndelete=0}
+
+do_execsql_test -db db2 3.10.1 { SELECT * FROM t1 }
+do_execsql_test 3.10.2 { 
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool ORDER BY 1;
+} {nref=1 nschema=1 ndelete=0 nref=2 nschema=1 ndelete=0}
+
+do_execsql_test -db db3 3.11.1 { SELECT * FROM t1 }
+do_execsql_test 3.11.2 { 
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=3 nschema=1 ndelete=0}
+
+#--------------------------------------------------------------------------
+catch {db1 close}
+catch {db2 close}
+catch {db3 close}
+reset_db
+do_execsql_test 4.0.1 {
+  CREATE TABLE x1(a, b, c);
+  CREATE INDEX x1a ON x1(a);
+  CREATE INDEX x1b ON x1(b);
+}
+do_test 4.0.2 {
+  db close
+  for {set i 1} {$i < 6} {incr i} {
+    forcedelete test.db${i}-journal test.db${i}-wal test.db${i}-wal2 
+    forcecopy test.db test.db${i}
+  }
+  sqlite3 db  test.db
+  sqlite3 db2 test.db -shared-schema 1
+} {}
+
+register_schemapool_module db
+do_execsql_test 4.0.3 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {}
+
+do_test 4.1.1 {
+  execsql { 
+    ATTACH 'test.db1' AS db1; 
+    ATTACH 'test.db2' AS db2;
+    ATTACH 'test.db3' AS db3;
+    ATTACH 'test.db4' AS db4;
+    ATTACH 'test.db5' AS db5;
+  } db2
+} {}
+do_execsql_test 4.1.2 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=1 nschema=1 ndelete=0}
+do_execsql_test -db db2 4.1.3 {
+  SELECT * FROM db3.x1
+}
+do_execsql_test 4.1.4 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=2 nschema=1 ndelete=0}
+do_execsql_test -db db2 4.1.5 {
+  SELECT * FROM db2.x1
+}
+do_execsql_test 4.1.6 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=3 nschema=1 ndelete=0}
+do_execsql_test -db db2 4.1.7 {
+  SELECT * FROM x1
+}
+do_execsql_test 4.1.8 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=3 nschema=1 ndelete=0}
+
+do_test 4.2.1 {
+  catchsql { SELECT * FROM abc } db2
+} {1 {no such table: abc}}
+do_execsql_test 4.2.2 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=6 nschema=1 ndelete=0}
+
+register_schemapool_module db2
+do_execsql_test -db db2 4.3.1 {
+  INSERT INTO x1 VALUES(1, 2, 3);
+  INSERT INTO db1.x1 VALUES(4, 5, 6);
+  INSERT INTO db2.x1 VALUES(7, 8, 9);
+  INSERT INTO db3.x1 VALUES(10, 11, 12);
+  INSERT INTO db4.x1 VALUES(13, 14, 15);
+  INSERT INTO db5.x1 VALUES(16, 17, 18);
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=6 nschema=1 ndelete=0}
+
+do_execsql_test -db db2 4.3.2 {
+  SELECT * FROM db5.x1;
+  SELECT * FROM db4.x1;
+  SELECT * FROM db3.x1;
+  SELECT * FROM db2.x1;
+  SELECT * FROM db1.x1;
+  SELECT * FROM x1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {
+  16 17 18  13 14 15  10 11 12  7 8 9  4 5 6  1 2 3
+  nref=6 nschema=1 ndelete=0
+}
+
+do_execsql_test -db db2 4.3.3 {
+  UPDATE x1 SET a=a+10;
+  UPDATE db5.x1 SET a=a+10;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {
+  nref=6 nschema=1 ndelete=0
+}
+
+do_execsql_test -db db2 4.3.4 {
+  SELECT * FROM db5.x1;
+  SELECT * FROM db4.x1;
+  SELECT * FROM db3.x1;
+  SELECT * FROM db2.x1;
+  SELECT * FROM db1.x1;
+  SELECT * FROM x1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {
+  26 17 18  13 14 15  10 11 12  7 8 9  4 5 6  11 2 3
+  nref=6 nschema=1 ndelete=0
+}
+
+do_execsql_test -db db2 4.3.5 {
+  DELETE FROM db3.x1;
+  DELETE FROM x1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {
+  nref=6 nschema=1 ndelete=0
+}
+
+do_execsql_test -db db2 4.3.6 {
+  SELECT * FROM db5.x1;
+  SELECT * FROM db4.x1;
+  SELECT * FROM db3.x1;
+  SELECT * FROM db2.x1;
+  SELECT * FROM db1.x1;
+  SELECT * FROM x1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {
+  26 17 18  13 14 15  7 8 9  4 5 6 
+  nref=6 nschema=1 ndelete=0
+}
+
+do_execsql_test -db db2 4.3.6 {
+  SELECT * FROM db5.x1, db4.x1, db1.x1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {26 17 18 13 14 15 4 5 6 nref=6 nschema=3 ndelete=0}
+
+#--------------------------------------------------------------------------
+# Test the incremental-blob API with REUSE_SCHEMA connections.
+#
+catch {db1 close}
+catch {db2 close}
+catch {db3 close}
+reset_db
+do_execsql_test 5.0.1 {
+  CREATE TABLE bbb(a INTEGER PRIMARY KEY, b);
+}
+db close
+do_test 5.0.2 {
+  sqlite3 db2 test.db -shared-schema 1
+  register_schemapool_module db2
+  for {set i 1} {$i<6} {incr i} {
+    forcedelete test.db${i}-journal test.db${i}-wal test.db${i}-wal2 
+    forcecopy test.db test.db${i}
+    sqlite3 db test.db${i}
+    db eval { INSERT INTO bbb VALUES(123, 'database_' || $i) }
+    db close
+    db2 eval "ATTACH 'test.db${i}' AS db${i}"
+  }
+  execsql {
+    SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+      FROM schemapool;
+  } db2
+} {nref=6 nschema=1 ndelete=0}
+
+do_test 5.1.1 {
+  set res [list]
+  for {set i 1} {$i<6} {incr i} {
+    set chan [db2 incrblob db${i} bbb b 123]
+    lappend res [gets $chan]
+    close $chan
+  }
+  set res
+} {database_1 database_2 database_3 database_4 database_5}
+
+do_execsql_test -db db2 5.1.2 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=6 nschema=1 ndelete=0}
+
+do_test 5.2.1 {
+  sqlite3_table_column_metadata db2 main bbb a
+} {INTEGER BINARY 0 1 0}
+do_test 5.2.2 {
+  sqlite3_table_column_metadata db2 main bbb b
+} {{} BINARY 0 0 0}
+
+do_execsql_test -db db2 5.2.3 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {nref=6 nschema=1 ndelete=0}
+
+do_execsql_test -db db2 5.2.4 {
+  PRAGMA integrity_check;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete
+  FROM schemapool;
+} {ok nref=6 nschema=1 ndelete=5}
+
+finish_test
+
@@ -0,0 +1,355 @@
+# 2019 February 12
+#
+# 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 reuse3
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE, z);
+  CREATE INDEX i1 ON t1(z);
+  CREATE TABLE t2(a);
+} {}
+
+db close
+sqlite3 db test.db -shared-schema 1
+
+do_execsql_test 1.1 {
+  CREATE TEMP VIEW v1 AS SELECT * FROM t1;
+  SELECT * FROM v1;
+}
+
+do_execsql_test 1.2 {
+  CREATE TEMP TRIGGER tr1 AFTER INSERT ON t1 BEGIN
+    INSERT INTO t2 VALUES(new.x);
+  END;
+}
+
+do_execsql_test 1.3 {
+  INSERT INTO t1 VALUES(1, 2, 3);
+}
+
+do_execsql_test 1.4 {
+  SELECT * FROM t2
+} {1}
+
+do_execsql_test 1.5 {
+  SELECT * FROM v1
+} {1 2 3}
+
+do_execsql_test 1.6 {
+  BEGIN;
+    DROP TRIGGER tr1;
+  ROLLBACK;
+}
+
+do_execsql_test 1.7 {
+  SELECT * FROM v1
+} {1 2 3}
+
+do_execsql_test 1.8 {
+  INSERT INTO t1 VALUES(4, 5, 6);
+  SELECT * FROM t2
+} {1 4}
+
+do_execsql_test 1.9 {
+  SELECT * FROM v1
+} {1 2 3 4 5 6}
+
+#-------------------------------------------------------------------------
+# Test error messages when parsing the schema with a REUSE_SCHEMA 
+# connection.
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE x1(a, b, c);
+  CREATE TABLE y1(d, e, f);
+  PRAGMA writable_schema = 1;
+  UPDATE sqlite_master SET sql = 'CREATE TBL y1(d, e, f)' WHERE name = 'y1';
+}
+db close
+
+sqlite3 db test.db -shared-schema 1
+do_catchsql_test 2.1 {
+  SELECT * FROM x1;
+} {1 {malformed database schema (y1) - near "TBL": syntax error}}
+
+do_catchsql_test 2.2 {
+  SELECT * FROM x1;
+} {1 {malformed database schema (y1) - near "TBL": syntax error}}
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE x1(a, b, c);
+  CREATE INDEX i1 ON x1(a, b, c);
+  CREATE TRIGGER tr1 AFTER INSERT ON x1 BEGIN
+    SELECT 1, 2, 3, 4, 5;
+  END;
+  INSERT INTO x1 VALUES(1, 2, 3);
+}
+sqlite3 db1 test.db -shared-schema 1
+
+do_test 3.1 {
+  execsql { SELECT * FROM x1 } db1
+  set N [lindex [sqlite3_db_status db1 SCHEMA_USED 0] 1]
+  expr $N==$N
+} 1
+
+sqlite3 db2 test.db -shared-schema 1
+do_test 3.2 {
+  execsql { SELECT * FROM x1 } db2
+  set N2 [lindex [sqlite3_db_status db2 SCHEMA_USED 0] 1]
+  expr $N2>($N/2) && $N2<($N/2)+400
+} 1
+
+sqlite3 db3 test.db -shared-schema 1
+sqlite3 db4 test.db -shared-schema 1
+do_test 3.3 {
+  execsql { SELECT * FROM x1 } db3
+  execsql { SELECT * FROM x1 } db4
+  set N4 [lindex [sqlite3_db_status db2 SCHEMA_USED 0] 1]
+  set M [expr 2*($N-$N2)]
+  set {} {}
+} {}
+do_test 3.3.1 { expr {(($M / 4) + $N-$M)} } "#/$N4/"
+
+catch { db1 close }
+catch { db2 close }
+catch { db3 close }
+catch { db4 close }
+
+#-------------------------------------------------------------------------
+# 4.1 Test the REINDEX command.
+# 4.2 Test CREATE TEMP ... commands.
+#
+reset_db
+do_execsql_test 4.1.0 {
+  CREATE TABLE x1(a, b, c);
+  CREATE INDEX x1a ON x1(a);
+  CREATE INDEX x1b ON x1(b);
+  CREATE INDEX x1c ON x1(c);
+}
+db close
+sqlite3 db test.db -shared-schema 1
+
+do_execsql_test 4.1.1 {
+  REINDEX x1;
+  REINDEX x1a;
+  REINDEX x1b;
+  REINDEX x1c;
+  REINDEX;
+}
+
+do_test 4.1.2 {
+  for {set i 1} {$i < 5} {incr i} {
+    forcedelete test.db${i} test.db${i}-wal test.db${i}-journal
+    forcecopy test.db test.db${i}
+    execsql "ATTACH 'test.db${i}' AS db${i}"
+  }
+  register_schemapool_module db
+  set {} {}
+  execsql { 
+    SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool 
+  }
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.1.3 {
+  REINDEX  x1;
+  REINDEX  x1a;
+  REINDEX  x1b;
+  REINDEX  x1c;
+  REINDEX  db1.x1a;
+  REINDEX  db2.x1b;
+  REINDEX  db3.x1c;
+}
+
+do_execsql_test 4.1.4 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool 
+} {nref=5 nschema=1 ndelete=28}
+
+#-------------------------------------------------------------------------
+db close
+sqlite3 db test.db -shared-schema 1
+register_schemapool_module db
+do_execsql_test 4.2.0 {
+  ATTACH 'test.db1' AS db1;
+  ATTACH 'test.db2' AS db2;
+  ATTACH 'test.db3' AS db3;
+  ATTACH 'test.db4' AS db4;
+
+  SELECT * FROM db1.x1;
+  SELECT * FROM db2.x1;
+  SELECT * FROM db3.x1;
+  SELECT * FROM db4.x1;
+}
+
+do_execsql_test 4.2.1 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.2.2 {
+  CREATE TEMP TABLE t1(a, b, c);
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.2.3 {
+  CREATE INDEX t1a ON t1(a);
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.2.4 {
+  CREATE TRIGGER tr1 AFTER INSERT ON t1 BEGIN
+    SELECT 1,2,3,4;
+  END;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.2.5 {
+  DROP TABLE t1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.2.6 {
+  CREATE TEMP TRIGGER tr1 AFTER INSERT ON db2.x1 BEGIN
+    SELECT 1,2,3,4;
+  END;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=0}
+
+do_execsql_test 4.2.7 {
+  DROP TRIGGER tr1;
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema, 'ndelete=' || nDelete 
+    FROM schemapool; 
+} {nref=5 nschema=1 ndelete=4}
+
+#--------------------------------------------------------------------------
+reset_db
+do_execsql_test 5.0 {
+  CREATE TABLE t1(a, b);
+  CREATE TABLE t2(a, b);
+  CREATE TABLE t3(a, b);
+}
+
+sqlite3 db2 test.db -shared-schema 1
+register_schemapool_module db2
+
+do_execsql_test 5.1 {
+  PRAGMA writable_schema = 1;
+  UPDATE sqlite_master SET sql='CREATE TABLE t3 a,b' WHERE name = 't3';
+}
+
+do_test 5.2 { 
+  catchsql { SELECT * FROM t1 } db2
+} {1 {malformed database schema (t3) - near "a": syntax error}}
+
+do_test 5.3 { 
+  catchsql { SELECT nref,nschema FROM schemapool } db2
+} {1 {malformed database schema (t3) - near "a": syntax error}}
+
+do_execsql_test 5.4 {
+  PRAGMA writable_schema = 1;
+  UPDATE sqlite_master SET sql='CREATE TABLE t3(a,b)' WHERE name = 't3';
+}
+
+do_test 5.5 { 
+  catchsql { SELECT nref,nschema FROM schemapool } db2
+} {0 {1 1}}
+
+db2 close
+db close
+do_test 5.6.1 {
+  forcedelete test.db2 test.db2-wal test.db2-journal
+  forcecopy test.db test.db2
+  sqlite3 db test.db
+  sqlite3 db2 test.db  -shared-schema 1
+  sqlite3 db3 test.db2 -shared-schema 1
+  register_schemapool_module db
+} {}
+
+do_execsql_test -db db2 5.6.2 { SELECT * FROM t1 }
+do_execsql_test -db db3 5.6.3 { SELECT * FROM t1 }
+do_execsql_test 5.6.4 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema FROM schemapool; 
+  CREATE TABLE t4(x);
+  DROP TABLE t4;
+} {nref=2 nschema=1}
+do_execsql_test -db db2 5.6.5 { SELECT * FROM t1 }
+do_execsql_test -db db3 5.6.6 { SELECT * FROM t1 }
+do_execsql_test 5.6.7 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema FROM schemapool; 
+  ATTACH 'test.db2' AS db2;
+  CREATE TABLE db2.t4(x);
+  DROP TABLE db2.t4;
+} {nref=1 nschema=1 nref=1 nschema=1}
+do_execsql_test -db db2 5.6.8 { SELECT * FROM t1 }
+do_execsql_test -db db3 5.6.9 { SELECT * FROM t1 }
+do_execsql_test 5.6.10 {
+  SELECT 'nref=' || nRef, 'nschema=' || nSchema FROM schemapool; 
+} {nref=2 nschema=1}
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 6.0 {
+  CREATE TABLE t1(a, b);
+  CREATE TABLE t2(a, b);
+  CREATE TABLE t3(a, b);
+}
+
+do_test 6.1 {
+  db close
+  sqlite3 db test.db -shared-schema 1
+  for {set i 1} {$i < 5} {incr i} {
+    set base "test.db$i"
+    set nm "aux$i"
+    forcedelete $base $base-wal $base-journal
+    forcecopy test.db $base
+    execsql "ATTACH '$base' AS $nm"
+  }
+} {}
+
+do_test 6.2 {
+  set N1 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  set N2 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  expr {$N1>0 && $N2>0 && $N1==$N2}
+} {1}
+
+do_test 6.3 {
+  execsql { SELECT * FROM main.t1 }
+  set N1 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  set N2 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  expr {$N1>0 && $N2>0 && $N1==$N2}
+} {1}
+
+do_test 6.4 {
+  execsql { SELECT * FROM aux1.t1 }
+  set N3 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  set N4 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  list $N3 $N4
+} "#/$N1 $N1/"
+
+finish_test
+
@@ -0,0 +1,173 @@
+# 2019 February 12
+#
+# 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 $testdir/tester.tcl
+set testprefix reuse4
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+foreach {tn sharedschema} {
+  1 0  
+  2 1  
+} {
+  reset_db
+
+  do_execsql_test 1.$tn.0 {
+    CREATE TABLE x1(a, b);
+    CREATE INDEX x1a ON x1(a);
+    CREATE INDEX x1b ON x1(b);
+    CREATE TABLE x2(a, b);
+  }
+  db close
+  
+  do_test 1.$tn.1 {
+    for {set i 1} {$i<4} {incr i} {
+      forcedelete test.db$i test.db$i-journal test.db$i-wal
+      forcecopy test.db test.db$i
+    }
+  
+    sqlite3 db test.db -shared-schema $sharedschema
+    for {set i 1} {$i<4} {incr i} {
+      execsql " ATTACH 'test.db$i' AS db$i "
+    }
+  } {}
+  
+  do_execsql_test 1.$tn.2 {
+    WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<10 )
+    INSERT INTO x1 SELECT i, i FROM s;
+  
+    INSERT INTO db3.x2 SELECT * FROM x1;
+    INSERT INTO db2.x1 SELECT * FROM db3.x2;
+    CREATE TEMP TRIGGER tr1 AFTER INSERT ON db2.x2 BEGIN
+      INSERT INTO x1 VALUES(new.a, new.b);
+    END;
+    INSERT INTO db2.x2 SELECT * FROM x1 WHERE a%2;
+    DELETE FROM x1 WHERE a<3;
+    INSERT INTO db3.x1 SELECT * FROM db2.x2;
+  
+    DETACH db3;
+    ATTACH 'test.db3' AS db3;
+  
+    UPDATE db3.x1 SET a=a-10 WHERE b NOT IN (SELECT b FROM db2.x2);
+  
+    CREATE TEMP TABLE x1(a, b);
+    INSERT INTO db2.x2 VALUES(50, 60), (60, 70), (80, 90);
+    ALTER TABLE x1 RENAME TO x2;
+    ALTER TABLE x2 ADD COLUMN c;
+    ALTER TABLE x2 RENAME a TO aaa;
+    DELETE FROM x1 WHERE b>8;
+    UPDATE db3.x2 SET b=b*10;
+  
+    BEGIN;
+      CREATE TEMP TABLE x5(x);
+      INSERT INTO x5 VALUES(1);
+    ROLLBACK;
+  
+    INSERT INTO main.x2 VALUES(123, 456);
+  }
+  
+  integrity_check 1.$tn.3
+  
+  do_execsql_test 1.$tn.4 {
+    SELECT * FROM main.x1; SELECT 'xxx';
+    SELECT * FROM main.x2; SELECT 'xxx';
+    SELECT * FROM temp.x2; SELECT 'xxx';
+  
+    SELECT * FROM db1.x1; SELECT 'xxx';
+    SELECT * FROM db1.x2; SELECT 'xxx';
+    SELECT * FROM db2.x1; SELECT 'xxx';
+    SELECT * FROM db2.x2; SELECT 'xxx';
+    SELECT * FROM db3.x1; SELECT 'xxx';
+    SELECT * FROM db3.x2; SELECT 'xxx';
+  } {
+    3 3 4 4 5 5 6 6 7 7 8 8 3 3 5 5 7 7 xxx 
+    123 456 xxx 
+    50 60 {} 60 70 {} 80 90 {} xxx
+    xxx
+    xxx
+    1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 xxx
+    1 1 3 3 5 5 7 7 9 9 50 60 60 70 80 90 xxx
+    1 1 3 3  5 5 7 7 9 9 xxx 
+    1 10 2 20 3 30 4 40 5 50 6 60 7 70 8 80 9 90 10 100 xxx
+  }
+  
+  do_test 1.$tn.5.1 {
+    sqlite3 db2 test.db
+    db2 eval { CREATE TABLE x3(x) }
+  } {}
+  do_execsql_test 1.$tn.5.2 {
+    SELECT * FROM main.x1; SELECT 'xxx';
+    SELECT * FROM main.x2; SELECT 'xxx';
+    SELECT * FROM main.x3; SELECT 'xxx';
+  } {
+    3 3 4 4 5 5 6 6 7 7 8 8 3 3 5 5 7 7 xxx 
+    123 456 xxx 
+    xxx
+  }
+}
+
+#-------------------------------------------------------------------------
+# Test some PRAGMA statements with shared-schema connections.
+#
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE t1(a, b, c);
+  CREATE INDEX t1abc ON t1(a, b, c);
+}
+
+foreach {tn pragma nSchema nDelete} {
+  1 "PRAGMA synchronous = OFF"     1 0
+  2 "PRAGMA cache_size = 200"      1 0
+  3 "PRAGMA aux2.integrity_check"  1 0
+  4 "PRAGMA      integrity_check"  1 5
+  5 "PRAGMA index_info=t1abc"      1 5
+  6 "PRAGMA aux3.index_info=t1abc" 1 0
+  7 "PRAGMA journal_mode"          1 0
+  8 "PRAGMA aux2.wal_checkpoint"   1 0
+  9 "PRAGMA wal_checkpoint"        1 0
+} {
+  do_test 2.$tn.1 {
+    catch { db close }
+    catch { db2 close }
+    for {set i 1} {$i < 6} {incr i} {
+      forcedelete "test.db$i" "test.db${i}-wal" "test.db${i}-journal"
+      forcecopy test.db test.db$i
+    }
+    sqlite3 db2 test.db -shared-schema 1
+    for {set i 1} {$i < 6} {incr i} {
+      execsql "ATTACH 'test.db$i' AS aux$i" db2
+    }
+  } {}
+
+  sqlite3 db test.db
+  register_schemapool_module db
+
+  do_test 2.$tn.2 {
+    execsql $pragma db2
+    execsql { SELECT 'nschema='||nschema, 'ndelete='||nDelete FROM schemapool }
+  } "nschema=$nSchema ndelete=$nDelete"
+
+  do_test 2.$tn.3 {
+    execsql {
+      SELECT * FROM main.t1,aux1.t1,aux2.t1,aux3.t1,aux4.t1,aux5.t1
+    } db2
+    execsql { SELECT 'nschema=' || nschema, 'nref=' || nref FROM schemapool }
+  } "nschema=6 nref=6"
+}
+
+finish_test
+
@@ -0,0 +1,125 @@
+# 2019 February 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
+set testprefix reuse5
+set CLI [test_find_cli]
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x, y);
+  CREATE TABLE t2(a, b, c);
+  CREATE INDEX t1x ON t1(x);
+  CREATE INDEX t1y ON t1(y);
+  CREATE VIEW v1 AS SELECT * FROM t2;
+}
+
+foreach {tn sql out1 out2} {
+  1 {
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(a, b, c);
+    CREATE INDEX t1x ON t1(x);
+    CREATE INDEX t1y ON t1(y);
+    CREATE VIEW v1 AS SELECT * FROM t2;
+  } {
+    test.db2 is compatible
+  } {}
+
+  2 {
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(a, b, c);
+    CREATE INDEX t1x ON t1(x);
+    CREATE INDEX t1y ON t1(y);
+    CREATE VIEW v1 AS SELECT * FROM t2;
+    CREATE TABLE x1(x);
+    DROP TABLE x1;
+  } {
+    test.db2 is NOT compatible (schema cookie)
+  } {
+    Fixing test.db2... test.db2 is compatible
+  }
+
+  3 {
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(a, b, c);
+    CREATE INDEX t1y ON t1(y);
+    CREATE VIEW v1 AS SELECT * FROM t2;
+  } {
+    test.db2 is NOT compatible (objects)
+  } {}
+
+  4 {
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(a, b, c);
+    CREATE INDEX t1x ON t1(X);
+    CREATE INDEX t1y ON t1(y);
+    CREATE VIEW v1 AS SELECT * FROM t2;
+  } {
+    test.db2 is NOT compatible (SQL)
+  } {}
+
+  5 {
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(a, b, c);
+    CREATE INDEX t1y ON t1(y);
+    CREATE INDEX t1x ON t1(x);
+    CREATE VIEW v1 AS SELECT * FROM t2;
+  } {
+    test.db2 is NOT compatible (root pages)
+  } {
+    Fixing test.db2... test.db2 is compatible
+  }
+
+  6 {
+    CREATE TABLE t1(x, y);
+    CREATE TABLE t2(a, b, c);
+    CREATE INDEX t1x ON t1(x);
+    CREATE INDEX t1y ON t1(y);
+    CREATE VIEW v1 AS SELECT * FROM t2;
+    DROP INDEX t1x;
+    CREATE INDEX t1x ON t1(x);
+  } {
+    test.db2 is NOT compatible (order of sqlite_master rows)
+  } {
+    Fixing test.db2... test.db2 is compatible
+  }
+
+} {
+  forcedelete test.db2
+  sqlite3 db2 test.db2
+  db2 eval $sql
+  db2 close
+
+  if {$out2==""} {set out2 $out1}
+
+  do_test 1.$tn.1 {
+    catchcmd test.db ".shared-schema check test.db2"
+  } [list 0 [string trim $out1]]
+
+  do_test 1.$tn.2 {
+    catchcmd test.db ".shared-schema fix test.db2"
+  } [list 0 [string trim $out2]]
+
+  do_test 1.$tn.3 {
+    catchcmd test.db2 "PRAGMA integrity_check"
+  } [list 0 ok]
+}
+
+
+finish_test
+
@@ -0,0 +1,143 @@
+# 2019 February 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
+set testprefix reuse6
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x, y);
+  CREATE TABLE t2(a, b, c);
+  CREATE INDEX t1x ON t1(x);
+  CREATE INDEX t1y ON t1(y);
+  CREATE VIEW v1 AS SELECT * FROM t2;
+
+  INSERT INTO t1 VALUES(1, 2), (3, 4), (5, 6);
+  INSERT INTO t2 VALUES('a', 'b', 'c'), ('d', 'e', 'f'), ('g', 'h', 'i');
+
+  ATTACH 'test.db2' AS aux;
+  CREATE TABLE t3(i, ii);
+  INSERT INTO t3 VALUES(10, 20);
+}
+
+sqlite3 db1 test.db -shared-schema 1
+sqlite3 db2 test.db -shared-schema 1
+
+do_execsql_test -db db1 1.1 {
+  ATTACH 'test.db2' AS aux;
+}
+
+do_test 1.2 {
+  execsql {SELECT * FROM t3} db1
+} {10 20}
+
+do_execsql_test -db db2 1.3 {
+  ATTACH 'test.db2' AS aux;
+}
+
+do_test 1.3 {
+  execsql {SELECT * FROM t3} db1
+} {10 20}
+
+do_execsql_test -db db2 1.5 {
+  SELECT * FROM t3;
+} {10 20}
+
+do_test 1.6 {
+  execsql {SELECT * FROM t3} db1
+} {10 20}
+
+db1 close
+db2 close
+
+#-------------------------------------------------------------------------
+reset_db
+forcedelete test.db2
+forcedelete test.db3
+do_execsql_test 2.0 {
+  CREATE TABLE t1(x, y);
+  ATTACH 'test.db2' AS aux2;
+  CREATE TABLE aux2.t2(x, y);
+  ATTACH 'test.db3' AS aux3;
+  CREATE TABLE aux3.t3(x, y);
+}
+
+sqlite3 db1 test.db -shared-schema 1
+do_execsql_test -db db1 2.1 {
+  ATTACH 'test.db2' AS aux2;
+  ATTACH 'test.db3' AS aux3;
+}
+
+do_test 2.2.1 {
+  catchsql { SELECT * FROM aux2.nosuchtable } db1
+} {1 {no such table: aux2.nosuchtable}}
+do_test 2.2.2 {
+  sqlite3_errcode db1
+} {SQLITE_ERROR}
+db1 close
+
+#-------------------------------------------------------------------------
+reset_db
+forcedelete test.db2
+ifcapable fts5 {
+  do_execsql_test 3.0 {
+    CREATE VIRTUAL TABLE ft USING fts5(a, b);
+    ATTACH 'test.db2' AS aux;
+    CREATE TABLE aux.t1(x, y, z);
+  }
+
+  sqlite3 db1 test.db -shared-schema 1
+  do_execsql_test -db db1 3.1 {
+    ATTACH 'test.db2' AS aux;
+  }
+
+  do_execsql_test -db db1 3.2 {
+    SELECT * FROM main.ft, aux.t1;
+  }
+  db1 close
+}
+
+#-------------------------------------------------------------------------
+reset_db
+forcedelete test.db2
+ifcapable fts5 {
+  do_execsql_test 4.0 {
+    CREATE VIRTUAL TABLE ft USING fts5(a, b);
+  }
+  forcecopy test.db test.db2
+
+  sqlite3 db1 test.db -shared-schema 1
+  do_execsql_test -db db1 4.1 {
+    ATTACH 'test.db2' AS aux;
+    SELECT * FROM main.ft;
+    SELECT * FROM aux.ft;
+  }
+
+  do_execsql_test -db db1 4.2 {
+    SELECT * FROM main.ft, aux.ft
+  }
+}
+
+
+
+
+
+
+
+finish_test
+
@@ -0,0 +1,54 @@
+# 2019 February 12
+#
+# 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 reusefault
+
+ifcapable !sharedschema {
+  finish_test
+  return
+}
+
+do_execsql_test 1.0 {
+  PRAGMA cache_size = 10;
+  CREATE TABLE t1(a UNIQUE, b UNIQUE);
+  INSERT INTO t1 VALUES(1, 2), (3, 4);
+}
+faultsim_save_and_close
+
+do_faultsim_test 1.1 -prep {
+  faultsim_restore
+  sqlite3 db test.db -shared-schema 1
+} -body {
+  execsql { SELECT * FROM t1 }
+} -test {
+  faultsim_test_result {0 {1 2 3 4}}
+}
+
+do_faultsim_test 1.2 -prep {
+  faultsim_restore
+  sqlite3 db test.db -shared-schema 1
+  execsql { SELECT * FROM t1 }
+  sqlite3 db2 test.db
+  db2 eval {CREATE TABLE a(a)}
+  db2 close
+} -body {
+  execsql { SELECT  * FROM t1 }
+} -test {
+  faultsim_test_result {0 {1 2 3 4}}
+}
+
+
+finish_test
+
@@ -113,6 +113,33 @@ do_execsql_test 4.1 {
  CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT);
  SELECT 1 FROM (SELECT DISTINCT name COLLATE rtrim FROM sqlite_schema
                 UNION ALL SELECT a FROM t1);
-} 1
+} {1 1}
+
+do_execsql_test 4.2 {
+  SELECT DISTINCT name COLLATE rtrim FROM sqlite_schema 
+    UNION ALL 
+  SELECT a FROM t1
+} {v1 t1}
+
+#-------------------------------------------------------------------------
+# forum post https://sqlite.org/forum/forumpost/b83c7b2168
+#
+reset_db
+do_execsql_test 5.0 {
+  CREATE TABLE t1 (val1);
+  INSERT INTO t1 VALUES(4);
+  INSERT INTO t1 VALUES(5);
+  CREATE TABLE t2 (val2);
+}
+do_execsql_test 5.1 {
+  SELECT DISTINCT val1 FROM t1 UNION ALL SELECT val2 FROM t2;
+} {
+  4 5
+}
+do_execsql_test 5.2 {
+  SELECT count(1234) FROM (
+    SELECT DISTINCT val1 FROM t1 UNION ALL SELECT val2 FROM t2
+  )
+} {2}

 finish_test
@@ -26,6 +26,9 @@ set testprefix tcl
 # Check the error messages generated by tclsqlite
 #
 set r "sqlite_orig HANDLE ?FILENAME? ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN? ?-nofollow BOOLEAN? ?-nomutex BOOLEAN? ?-fullmutex BOOLEAN? ?-uri BOOLEAN?"
+ifcapable sharedschema {
+  append r " ?-shared-schema BOOLEAN?"
+}
 if {[sqlite3 -has-codec]} {
  append r " ?-key CODECKEY?"
 }
@@ -880,7 +880,7 @@ proc catchcmd {db {cmd ""}} {
  set out [open cmds.txt w]
  puts $out $cmd
  close $out
-  set line "exec $CLI $db < cmds.txt"
+  set line "exec $CLI --unsafe-testing $db < cmds.txt"
  set rc [catch { eval $line } msg]
  list $rc $msg
 }
@@ -98,7 +98,10 @@ namespace eval trd {
  set build(All-O0) {
    -O0 --enable-all
  }
-  set build(All-Sanitize) { --enable-all -fsanitize=address,undefined }
+  set build(All-Sanitize) { 
+    -DSQLITE_OMIT_LOOKASIDE=1
+    --enable-all -fsanitize=address,undefined 
+  }

  set build(Sanitize) {
    CC=clang -fsanitize=address,undefined
@@ -38,7 +38,7 @@
 #define SEL(e) ((e)->iLine = ((e)->rc ? (e)->iLine : __LINE__))

 /* Database functions */
-#define opendb(w,x,y,z)         (SEL(w), opendb_x(w,x,y,z))
+#define opendb(w,x,y,z,f)       (SEL(w), opendb_x(w,x,y,z,f))
 #define closedb(y,z)            (SEL(y), closedb_x(y,z))

 /* Functions to execute SQL */
@@ -545,11 +545,14 @@ static void opendb_x(
  Error *pErr,                    /* IN/OUT: Error code */
  Sqlite *pDb,                    /* OUT: Database handle */
  const char *zFile,              /* Database file name */
-  int bDelete                     /* True to delete db file before opening */
+  int bDelete,                    /* True to delete db file before opening */
+  int flags
 ){
  if( pErr->rc==SQLITE_OK ){
    int rc;
-    int flags = SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE | SQLITE_OPEN_URI;
+    if( flags==0 ){
+      flags = SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE | SQLITE_OPEN_URI;
+    }
    if( bDelete ) unlink(zFile);
    rc = sqlite3_open_v2(zFile, &pDb->db, flags, 0);
    if( rc ){
@@ -985,7 +988,7 @@ static char *walthread1_thread(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */
  int nIter = 0;                  /* Iterations so far */

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    const char *azSql[] = {
      "SELECT md5sum(x) FROM t1 WHERE rowid != (SELECT max(rowid) FROM t1)",
@@ -1024,7 +1027,7 @@ static char *walthread1_ckpt_thread(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */
  int nCkpt = 0;                  /* Checkpoints so far */

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    sqlite3_sleep(500);
    execsql(&err, &db, "PRAGMA wal_checkpoint");
@@ -1043,7 +1046,7 @@ static void walthread1(int nMs){
  Threadset threads = {0};        /* Test threads */
  int i;                          /* Iterator variable */

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db,
      "PRAGMA journal_mode = WAL;"
      "CREATE TABLE t1(x PRIMARY KEY);"
@@ -1076,7 +1079,7 @@ static char *walthread2_thread(int iTid, void *pArg){
    int journal_exists = 0;
    int wal_exists = 0;

-    opendb(&err, &db, "test.db", 0);
+    opendb(&err, &db, "test.db", 0, 0);

    sql_script(&err, &db, zJournal);
    clear_error(&err, SQLITE_BUSY);
@@ -1106,7 +1109,7 @@ static void walthread2(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, "CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE)");
  closedb(&err, &db);

@@ -1126,7 +1129,7 @@ static char *walthread3_thread(int iTid, void *pArg){
  i64 iNextWrite;                 /* Next value this thread will write */
  int iArg = PTR2INT(pArg);

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  sql_script(&err, &db, "PRAGMA wal_autocheckpoint = 10");

  iNextWrite = iArg+1;
@@ -1163,7 +1166,7 @@ static void walthread3(int nMs){
  Threadset threads = {0};
  int i;

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
      "PRAGMA journal_mode = WAL;"
      "CREATE TABLE t1(cnt PRIMARY KEY, sum1, sum2);"
@@ -1186,7 +1189,7 @@ static char *walthread4_reader_thread(int iTid, void *pArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    integrity_check(&err, &db);
  }
@@ -1201,7 +1204,7 @@ static char *walthread4_writer_thread(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */
  i64 iRow = 1;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  sql_script(&err, &db, "PRAGMA wal_autocheckpoint = 15;");
  while( !timetostop(&err) ){
    execsql_i64(
@@ -1221,7 +1224,7 @@ static void walthread4(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
      "PRAGMA journal_mode = WAL;"
      "CREATE TABLE t1(a INTEGER PRIMARY KEY, b UNIQUE);"
@@ -1241,7 +1244,7 @@ static char *walthread5_thread(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */
  i64 nRow;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  nRow = execsql_i64(&err, &db, "SELECT count(*) FROM t1");
  closedb(&err, &db);

@@ -1254,7 +1257,7 @@ static void walthread5(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
      "PRAGMA wal_autocheckpoint = 0;"
      "PRAGMA page_size = 1024;"
@@ -1345,7 +1348,7 @@ static void cgt_pager_1(int nMs){
  Error err = {0};
  Sqlite db = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db,
      "PRAGMA cache_size = 2000;"
      "PRAGMA page_size = 1024;"
@@ -1374,7 +1377,7 @@ static char *dynamic_triggers_1(int iTid, void *pArg){
  int nDrop = 0;
  int nCreate = 0;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    int i;

@@ -1427,7 +1430,7 @@ static char *dynamic_triggers_2(int iTid, void *pArg){
  int nInsert = 0;
  int nDelete = 0;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    do {
      iVal = (iVal+1)%100;
@@ -1452,7 +1455,7 @@ static void dynamic_triggers(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
      "PRAGMA page_size = 1024;"
      "PRAGMA journal_mode = WAL;"
@@ -1492,6 +1495,7 @@ static void dynamic_triggers(int nMs){
 #include "tt3_lookaside1.c"
 #include "tt3_vacuum.c"
 #include "tt3_stress.c"
+#include "tt3_reuseschema.c"
 #include "tt3_shared.c"

 int main(int argc, char **argv){
@@ -1517,6 +1521,7 @@ int main(int argc, char **argv){
    { vacuum1,             "vacuum1", 10000 },
    { stress1,             "stress1", 10000 },
    { stress2,             "stress2", 60000 },
+    { reuse_schema_1,      "reuse_schema_1", 20000 },
    { shared1,             "shared1", 10000 },
  };
  static char *substArgv[] = { 0, "*", 0 };
@@ -70,7 +70,7 @@ static char *checkpoint_starvation_reader(int iTid, void *pArg){
  Error err = {0};
  Sqlite db = {0};

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    i64 iCount1, iCount2;
    sql_script(&err, &db, "BEGIN");
@@ -96,7 +96,7 @@ static void checkpoint_starvation_main(int nMs, CheckpointStarvationCtx *p){
  int nInsert = 0;
  int i;

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
      "PRAGMA page_size = 1024;"
      "PRAGMA journal_mode = WAL;"
@@ -19,7 +19,7 @@ static char *create_drop_index_thread(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */

  while( !timetostop(&err) ){
-    opendb(&err, &db, "test.db", 0);
+    opendb(&err, &db, "test.db", 0, 0);

    sql_script(&err, &db, 
      "DROP INDEX IF EXISTS i1;"
@@ -51,7 +51,7 @@ static void create_drop_index_1(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
     "CREATE TABLE t11(a, b, c, d);"
     "WITH data(x) AS (SELECT 1 UNION ALL SELECT x+1 FROM data WHERE x<100) "
@@ -22,7 +22,7 @@ static char *lookaside1_thread_reader(int iTid, void *pArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);

  while( !timetostop(&err) ){
    sqlite3_stmt *pStmt = 0;
@@ -47,7 +47,7 @@ static char *lookaside1_thread_writer(int iTid, void *pArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);

  do{
    sql_script(&err, &db, 
@@ -68,7 +68,7 @@ static void lookaside1(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
     "CREATE TABLE t1(x PRIMARY KEY) WITHOUT ROWID;"
     "WITH data(x,y) AS ("
@@ -0,0 +1,73 @@
+/*
+** 2014 December 9
+**
+** 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.
+**
+*************************************************************************
+**
+**     reuse_schema_1
+*/
+
+
+static char *reuse_schema_thread(int iTid, void *pArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  int iRep = 0;
+
+  while( !timetostop(&err) ){
+    int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_SHARED_SCHEMA;
+    opendb(&err, &db, "test.db", 0, f);
+
+    execsql_i64(&err, &db, "SELECT count(*) FROM t1");
+    sql_script(&err, &db, "ATTACH 'test.db2' AS aux");
+    execsql_i64(&err, &db, "SELECT count(*) FROM t1");
+
+    closedb(&err, &db);
+    iRep++;
+  }
+
+  print_and_free_err(&err);
+  return sqlite3_mprintf("%d", iRep);
+}
+
+static void reuse_schema_1(int nMs){
+  Error err = {0};
+  Sqlite db = {0};
+  Threadset threads = {0};
+
+  opendb(&err, &db, "test.db", 1, 0);
+  sql_script(&err, &db, 
+     "CREATE TABLE t1(a, b, c, d);"
+     "WITH data(x) AS (SELECT 1 UNION ALL SELECT x+1 FROM data WHERE x<100) "
+     "INSERT INTO t1 SELECT x,x,x,x FROM data;"
+  );
+  closedb(&err, &db);
+  opendb(&err, &db, "test.db2", 1, 0);
+  sql_script(&err, &db, 
+#ifdef SQLITE_ENABLE_FTS5
+     "CREATE VIRTUAL TABLE t2 USING fts5(a, b, c, d);"
+#else
+     "CREATE TABLE t2(a, b, c, d);"
+#endif
+     "WITH data(x) AS (SELECT 1 UNION ALL SELECT x+1 FROM data WHERE x<100) "
+     "INSERT INTO t2 SELECT x*2,x*2,x*2,x*2 FROM data;"
+  );
+  closedb(&err, &db);
+
+  setstoptime(&err, nMs);
+
+  launch_thread(&err, &threads, reuse_schema_thread, 0);
+  launch_thread(&err, &threads, reuse_schema_thread, 0);
+  launch_thread(&err, &threads, reuse_schema_thread, 0);
+  launch_thread(&err, &threads, reuse_schema_thread, 0);
+  launch_thread(&err, &threads, reuse_schema_thread, 0);
+
+  join_all_threads(&err, &threads);
+  sqlite3_enable_shared_cache(0);
+  print_and_free_err(&err);
+}
@@ -21,7 +21,7 @@ static char *stress_thread_1(int iTid, void *pArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    sql_script(&err, &db, "CREATE TABLE IF NOT EXISTS t1(a PRIMARY KEY, b)");
    clear_error(&err, SQLITE_LOCKED);
@@ -40,7 +40,7 @@ static char *stress_thread_2(int iTid, void *pArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */
  while( !timetostop(&err) ){
-    opendb(&err, &db, "test.db", 0);
+    opendb(&err, &db, "test.db", 0, 0);
    sql_script(&err, &db, "SELECT * FROM sqlite_schema;");
    clear_error(&err, SQLITE_LOCKED);
    closedb(&err, &db);
@@ -59,7 +59,7 @@ static char *stress_thread_3(int iTid, void *pArg){
  int i1 = 0;
  int i2 = 0;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    sql_script(&err, &db, "SELECT * FROM t1 ORDER BY a;");
    i1++;
@@ -82,11 +82,11 @@ static char *stress_thread_4(int iTid, void *pArg){
  int i2 = 0;
  int iArg = PTR2INT(pArg);

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    if( iArg ){
      closedb(&err, &db);
-      opendb(&err, &db, "test.db", 0);
+      opendb(&err, &db, "test.db", 0, 0);
    }
    sql_script(&err, &db, 
        "WITH loop(i) AS (SELECT 1 UNION ALL SELECT i+1 FROM loop LIMIT 200) "
@@ -113,12 +113,12 @@ static char *stress_thread_5(int iTid, void *pArg){
  int i1 = 0;
  int i2 = 0;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    i64 i = (i1 % 4);
    if( iArg ){
      closedb(&err, &db);
-      opendb(&err, &db, "test.db", 0);
+      opendb(&err, &db, "test.db", 0, 0);
    }
    execsql(&err, &db, "DELETE FROM t1 WHERE (rowid % 4)==:i", &i);
    i1++;
@@ -265,7 +265,7 @@ static char *stress2_workload19(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */
  const char *zDb = (const char*)pArg;
  while( !timetostop(&err) ){
-    opendb(&err, &db, zDb, 0);
+    opendb(&err, &db, zDb, 0, 0);
    sql_script(&err, &db, "SELECT * FROM sqlite_schema;");
    clear_error(&err, SQLITE_LOCKED);
    closedb(&err, &db);
@@ -290,7 +290,7 @@ static char *stress2_thread_wrapper(int iTid, void *pArg){

  while( !timetostop(&err) ){
    int cnt;
-    opendb(&err, &db, pCtx->zDb, 0);
+    opendb(&err, &db, pCtx->zDb, 0, 0);
    for(cnt=0; err.rc==SQLITE_OK && cnt<STRESS2_TABCNT; cnt++){
      pCtx->xProc(&err, &db, i1);
      i2 += (err.rc==SQLITE_OK);
@@ -342,7 +342,7 @@ static void stress2(int nMs){
  Threadset threads = {0};

  /* To make sure the db file is empty before commencing */
-  opendb(&err, &db, zDb, 1);
+  opendb(&err, &db, zDb, 1, 0);
  sql_script(&err, &db, 
      "CREATE TABLE IF NOT EXISTS t0(x PRIMARY KEY, y, z);"
      "CREATE INDEX IF NOT EXISTS i0 ON t0(y);"
@@ -25,7 +25,7 @@ static char *vacuum1_thread_writer(int iTid, void *pArg){
  Sqlite db = {0};                /* SQLite database connection */
  i64 i = 0;

-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);
  while( !timetostop(&err) ){
    i++;

@@ -52,7 +52,7 @@ static char *vacuum1_thread_writer(int iTid, void *pArg){
 static char *vacuum1_thread_vacuumer(int iTid, void *pArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */
-  opendb(&err, &db, "test.db", 0);
+  opendb(&err, &db, "test.db", 0, 0);

  do{
    sql_script(&err, &db, "VACUUM");
@@ -69,7 +69,7 @@ static void vacuum1(int nMs){
  Sqlite db = {0};
  Threadset threads = {0};

-  opendb(&err, &db, "test.db", 1);
+  opendb(&err, &db, "test.db", 1, 0);
  sql_script(&err, &db, 
     "CREATE TABLE t1(x PRIMARY KEY, y BLOB);"
     "CREATE INDEX i1 ON t1(y);"
@@ -25,6 +25,14 @@ VERSION=`cat $TOP/VERSION`
 HASH=`sed 's/^\(..........\).*/\1/' $TOP/manifest.uuid`
 DATETIME=`grep '^D' $TOP/manifest | sed -e 's/[^0-9]//g' -e 's/\(............\).*/\1/'`

+# Verify that the version number in the TEA autoconf file is correct.
+# Fail with an error if not.
+#
+if grep $VERSION autoconf/tea/configure.ac
+then echo "TEA version number ok"
+else echo "TEA version number mismatch.  Should be $VERSION"; exit 1
+fi
+
 # If this script is given an argument of --snapshot, then generate a
 # snapshot tarball named for the current checkout SHA1 hash, rather than
 # the version number.
@@ -12,7 +12,7 @@

 # Flag meanings:
 set flagMeaning(NeedSchema) {Force schema load before running}
-set flagMeaning(ReadOnly)   {Read-only HEADER_VALUE}
+set flagMeaning(OneSchema)  {Only a single schema required}
 set flagMeaning(Result0)    {Acts as query when no argument}
 set flagMeaning(Result1)    {Acts as query when has one argument}
 set flagMeaning(SchemaReq)  {Schema required - "main" is default}
@@ -150,7 +150,7 @@ set pragma_def {
  ARG:  SQLITE_CellSizeCk

  NAME: default_cache_size
-  FLAG: NeedSchema Result0 SchemaReq NoColumns1
+  FLAG: NeedSchema Result0 SchemaReq NoColumns1 OneSchema
  COLS: cache_size
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS) && !defined(SQLITE_OMIT_DEPRECATED)

@@ -163,12 +163,12 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: page_count
-  FLAG: NeedSchema Result0 SchemaReq
+  FLAG: NeedSchema Result0 SchemaReq OneSchema
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: max_page_count
  TYPE: PAGE_COUNT
-  FLAG: NeedSchema Result0 SchemaReq
+  FLAG: NeedSchema Result0 SchemaReq OneSchema
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: locking_mode
@@ -176,7 +176,7 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: journal_mode
-  FLAG: NeedSchema Result0 SchemaReq
+  FLAG: NeedSchema Result0 SchemaReq OneSchema
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: journal_size_limit
@@ -184,18 +184,18 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: cache_size
-  FLAG: NeedSchema Result0 SchemaReq NoColumns1
+  FLAG: NeedSchema Result0 SchemaReq NoColumns1 OneSchema
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: mmap_size
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: auto_vacuum
-  FLAG: NeedSchema Result0 SchemaReq NoColumns1
+  FLAG: NeedSchema Result0 SchemaReq NoColumns1 OneSchema
  IF:   !defined(SQLITE_OMIT_AUTOVACUUM)

  NAME: incremental_vacuum
-  FLAG: NeedSchema NoColumns
+  FLAG: NeedSchema NoColumns OneSchema
  IF:   !defined(SQLITE_OMIT_AUTOVACUUM)

  NAME: temp_store
@@ -215,7 +215,7 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS) && SQLITE_ENABLE_LOCKING_STYLE

  NAME: synchronous
-  FLAG: NeedSchema Result0 SchemaReq NoColumns1
+  FLAG: NeedSchema Result0 SchemaReq NoColumns1 OneSchema
  IF:   !defined(SQLITE_OMIT_PAGER_PRAGMAS)

  NAME: table_info
@@ -238,7 +238,7 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)

  NAME: stats
-  FLAG: NeedSchema Result0 SchemaReq
+  FLAG: NeedSchema Result0 SchemaReq OneSchema
  COLS: tbl idx wdth hght flgs
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS) && defined(SQLITE_DEBUG)

@@ -290,7 +290,7 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)

  NAME: foreign_key_list
-  FLAG: NeedSchema Result1 SchemaOpt
+  FLAG: NeedSchema Result1 SchemaOpt OneSchema
  COLS: id seq table from to on_update on_delete match
  IF:   !defined(SQLITE_OMIT_FOREIGN_KEY)

@@ -336,14 +336,14 @@ set pragma_def {

  NAME: data_version
  TYPE: HEADER_VALUE
-  ARG:  BTREE_DATA_VERSION
-  FLAG: ReadOnly Result0
+  ARG:  BTREE_DATA_VERSION|PRAGMA_HEADER_VALUE_READONLY
+  FLAG: Result0
  IF:   !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)

  NAME: freelist_count
  TYPE: HEADER_VALUE
-  ARG:  BTREE_FREE_PAGE_COUNT
-  FLAG: ReadOnly Result0
+  ARG:  BTREE_FREE_PAGE_COUNT|PRAGMA_HEADER_VALUE_READONLY
+  FLAG: Result0
  IF:   !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)

  NAME: application_id
@@ -357,7 +357,7 @@ set pragma_def {
  IF:   !defined(SQLITE_OMIT_COMPILEOPTION_DIAGS)

  NAME: wal_checkpoint
-  FLAG: NeedSchema
+  FLAG: NeedSchema OneSchema
  COLS: busy log checkpointed
  IF:   !defined(SQLITE_OMIT_WAL)

@@ -516,6 +516,12 @@ foreach f [lsort [array names allflags]] {
  set fv [expr {$fv*2}]
 }

+puts $fd "\n/* For PragTyp_HEADER_VALUE pragmas the Pragma.iArg value is set"
+puts $fd "** to the index of the header field to access (always 10 or less)."
+puts $fd "** Ored with HEADER_VALUE_READONLY if the field is read only. */"
+puts $fd "#define PRAGMA_HEADER_VALUE_READONLY 0x0100"
+puts $fd "#define PRAGMA_HEADER_VALUE_MASK 0x00FF\n"
+
 # Sort the column lists so that longer column lists occur first
 #
 proc colscmp {a b} {
@@ -0,0 +1,79 @@
+#!/usr/bin/tclsh
+#
+# Run this script from the top of the source tree in order to confirm that
+# various aspects of the source tree are up-to-date.  Items checked include:
+#
+#     *    Makefile.msc and autoconf/Makefile.msc agree
+#     *    src/ctime.tcl is consistent with tool/mkctimec.tcl
+#     *    VERSION agrees with autoconf/tea/configure.ac
+#     *    src/pragma.h agrees with tool/mkpragmatab.tcl
+#
+# Other tests might be added later.  
+#
+# Error messages are printed and the process exists non-zero if problems
+# are found.  If everything is ok, no output is generated and the process
+# exits with 0.
+#
+
+# Read an entire file.
+#
+proc readfile {filename} {
+  set fd [open $filename rb]
+  set txt [read $fd]
+  close $fd
+  return $txt
+}
+
+# Find the root of the tree.
+#
+set ROOT [file dir [file dir [file normalize $argv0]]]
+cd $ROOT
+
+# Name of the TCL interpreter
+#
+set TCLSH [info nameofexe]
+
+######################### autoconf/tea/configure.ac ###########################
+
+set confac [readfile $ROOT/autoconf/tea/configure.ac]
+set vers [readfile $ROOT/VERSION]
+set pattern {AC_INIT([sqlite],[}
+append pattern [string trim $vers]
+append pattern {])}
+if {[string first $pattern $confac]<=0} {
+  puts "ERROR: ./autoconf/tea/configure.ac does not agree with ./VERSION"
+  exit 1
+}
+
+######################### autoconf/Makefile.msc ###############################
+
+set f1 [readfile $ROOT/autoconf/Makefile.msc]
+exec mv $ROOT/autoconf/Makefile.msc $ROOT/autoconf/Makefile.msc.tmp
+exec $TCLSH $ROOT/tool/mkmsvcmin.tcl
+set f2 [readfile $ROOT/autoconf/Makefile.msc]
+exec mv $ROOT/autoconf/Makefile.msc.tmp $ROOT/autoconf/Makefile.msc
+if {$f1 != $f2} {
+  puts "ERROR: ./autoconf/Makefile.msc does not agree with ./Makefile.msc"
+}
+
+######################### src/pragma.h ########################################
+
+set f1 [readfile $ROOT/src/pragma.h]
+exec mv $ROOT/src/pragma.h $ROOT/src/pragma.h.tmp
+exec $TCLSH $ROOT/tool/mkpragmatab.tcl
+set f2 [readfile $ROOT/src/pragma.h]
+exec mv $ROOT/src/pragma.h.tmp $ROOT/src/pragma.h
+if {$f1 != $f2} {
+  puts "ERROR: ./src/pragma.h does not agree with ./tool/mkpragmatab.tcl"
+}
+
+######################### src/ctime.c ########################################
+
+set f1 [readfile $ROOT/src/ctime.c]
+exec mv $ROOT/src/ctime.c $ROOT/src/ctime.c.tmp
+exec $TCLSH $ROOT/tool/mkctimec.tcl
+set f2 [readfile $ROOT/src/ctime.c]
+exec mv $ROOT/src/ctime.c.tmp $ROOT/src/ctime.c
+if {$f1 != $f2} {
+  puts "ERROR: ./src/ctime.c does not agree with ./tool/mkctimec.tcl"
+}
@@ -1 +1 @@
 .43.0
 .43.2