Merge changes from branch-3.35. Specifically, fixes for a running RBU with a cksumvfs VFS.

FossilOrigin-Name: ca62c36b7f45369679cdc7acfcce108f897d5f7a2ac74bd603b45a024fe5e5bc

Makefile.in

@@ -418,6 +418,7 @@ TESTSRC = \
   $(TOP)/src/test_quota.c \
   $(TOP)/src/test_rtree.c \
   $(TOP)/src/test_schema.c \
+  $(TOP)/src/test_schemapool.c \
   $(TOP)/src/test_server.c \
   $(TOP)/src/test_superlock.c \
   $(TOP)/src/test_syscall.c \
@@ -477,6 +478,7 @@ 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 \

Makefile.msc

@@ -1538,6 +1538,7 @@ TESTSRC = \
   $(TOP)\src\test_quota.c \
   $(TOP)\src\test_rtree.c \
   $(TOP)\src\test_schema.c \
+  $(TOP)\src\test_schemapool.c \
   $(TOP)\src\test_server.c \
   $(TOP)\src\test_superlock.c \
   $(TOP)\src\test_syscall.c \

VERSION

@@ -1 +1 @@
-3.35.3
+3.35.5

configure

@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for sqlite 3.35.3.
+# Generated by GNU Autoconf 2.69 for sqlite 3.35.5.
 #
 #
 # 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='3.35.3'
-PACKAGE_STRING='sqlite 3.35.3'
+PACKAGE_VERSION='3.35.5'
+PACKAGE_STRING='sqlite 3.35.5'
 PACKAGE_BUGREPORT=''
 PACKAGE_URL=''
 
@@ -1467,7 +1467,7 @@ 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 3.35.3 to adapt to many kinds of systems.
+\`configure' configures sqlite 3.35.5 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1532,7 +1532,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of sqlite 3.35.3:";;
+     short | recursive ) echo "Configuration of sqlite 3.35.5:";;
    esac
   cat <<\_ACEOF
 
@@ -1660,7 +1660,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-sqlite configure 3.35.3
+sqlite configure 3.35.5
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2079,7 +2079,7 @@ 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 3.35.3, which was
+It was created by sqlite $as_me 3.35.5, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -12378,7 +12378,7 @@ cat >>$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 3.35.3, which was
+This file was extended by sqlite $as_me 3.35.5, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -12444,7 +12444,7 @@ _ACEOF
 cat >>$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 3.35.3
+sqlite config.status 3.35.5
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 

doc/shared_schema.md

@@ -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_open_v2() API with the SQLITE_OPEN_SHARED_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_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_OPEN_SHARED_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_stat\[14\] tables do not exist.
+
+For SQLITE_OPEN_SHARED_SCHEMA connections, the
+SQLITE_DBSTATUS_SCHEMA_USED sqlite3_db_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.

ext/misc/cksumvfs.c

@@ -579,6 +579,18 @@ static int cksmFileControl(sqlite3_file *pFile, int op, void *pArg){
   }else if( op==SQLITE_FCNTL_CKPT_START || op==SQLITE_FCNTL_CKPT_DONE ){
     p->inCkpt = op==SQLITE_FCNTL_CKPT_START;
     if( p->pPartner ) p->pPartner->inCkpt = p->inCkpt;
+  }else if( op==SQLITE_FCNTL_CKSM_FILE ){
+    /* This VFS needs to obtain a pointer to the corresponding database
+    ** file handle from within xOpen() calls to open wal files. To do this,
+    ** it uses the sqlite3_database_file_object() API to obtain a pointer
+    ** to the file-handle used by SQLite to access the db file. This is
+    ** fine if cksmvfs happens to be the top-level VFS, but not if there
+    ** are one or more wrapper VFS. To handle this case, this file-control
+    ** is used to extract the cksmvfs file-handle from any wrapper file 
+    ** handle.  */
+    sqlite3_file **ppFile = (sqlite3_file**)pArg;
+    *ppFile = (sqlite3_file*)p;
+    return SQLITE_OK;
   }
   rc = pFile->pMethods->xFileControl(pFile, op, pArg);
   if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){
@@ -688,6 +700,8 @@ static int cksmOpen(
   if( rc ) goto cksm_open_done;
   if( flags & SQLITE_OPEN_WAL ){
     sqlite3_file *pDb = sqlite3_database_file_object(zName);
+    rc = pDb->pMethods->xFileControl(pDb, SQLITE_FCNTL_CKSM_FILE, (void*)&pDb);
+    assert( rc==SQLITE_OK );
     p->pPartner = (CksmFile*)pDb;
     assert( p->pPartner->pPartner==0 );
     p->pPartner->pPartner = p;

ext/rbu/rbu1.test

@@ -132,6 +132,11 @@ foreach {tn3 create_vfs destroy_vfs} {
   } {
     sqlite3rbu_destroy_vfs myrbu
   }
+  3 {
+    sqlite3_register_cksumvfs
+  } {
+    sqlite3_unregister_cksumvfs
+  }
 } {
 
   eval $create_vfs

ext/rbu/sqlite3rbu.c

@@ -1620,7 +1620,9 @@ char *rbuVacuumIndexStart(
       zSep = "";
       for(iCol=0; iCol<pIter->nCol; iCol++){
         const char *zQuoted = (const char*)sqlite3_column_text(pSel, iCol);
-        if( zQuoted[0]=='N' ){
+        if( zQuoted==0 ){
+          p->rc = SQLITE_NOMEM;
+        }else if( zQuoted[0]=='N' ){
           bFailed = 1;
           break;
         }
@@ -4992,28 +4994,14 @@ static int rbuVfsOpen(
       rbu_file *pDb = rbuFindMaindb(pRbuVfs, zName, 0);
       if( pDb ){
         if( pDb->pRbu && pDb->pRbu->eStage==RBU_STAGE_OAL ){
-          /* This call is to open a *-wal file. Intead, open the *-oal. This
-          ** code ensures that the string passed to xOpen() is terminated by a
-          ** pair of '\0' bytes in case the VFS attempts to extract a URI 
-          ** parameter from it.  */
-          const char *zBase = zName;
-          size_t nCopy;
-          char *zCopy;
+          /* This call is to open a *-wal file. Intead, open the *-oal. */
+          size_t nOpen;
           if( rbuIsVacuum(pDb->pRbu) ){
-            zBase = sqlite3_db_filename(pDb->pRbu->dbRbu, "main");
-            zBase = sqlite3_filename_wal(zBase);
-          }
-          nCopy = strlen(zBase);
-          zCopy = sqlite3_malloc64(nCopy+2);
-          if( zCopy ){
-            memcpy(zCopy, zBase, nCopy);
-            zCopy[nCopy-3] = 'o';
-            zCopy[nCopy] = '\0';
-            zCopy[nCopy+1] = '\0';
-            zOpen = (const char*)(pFd->zDel = zCopy);
-          }else{
-            rc = SQLITE_NOMEM;
+            zOpen = sqlite3_db_filename(pDb->pRbu->dbRbu, "main");
+            zOpen = sqlite3_filename_wal(zOpen);
           }
+          nOpen = strlen(zOpen);
+          ((char*)zOpen)[nOpen-3] = 'o';
           pFd->pRbu = pDb->pRbu;
         }
         pDb->pWalFd = pFd;

main.mk

@@ -343,6 +343,7 @@ TESTSRC = \
   $(TOP)/src/test_quota.c \
   $(TOP)/src/test_rtree.c \
   $(TOP)/src/test_schema.c \
+  $(TOP)/src/test_schemapool.c \
   $(TOP)/src/test_server.c \
   $(TOP)/src/test_sqllog.c \
   $(TOP)/src/test_superlock.c \
@@ -397,6 +398,7 @@ 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 \

manifest

@@ -1,13 +1,13 @@
-C Fix\san\sassert()\sthat\sin\spreupdate-hook\slogic\s(not\snormally\sbuilt)\sthat\ncan\sbe\sfalse\swhen\srunning\sVACUUM\son\sa\scorrupt\sdatabase\sfile\sunder\nPRAGMA\swritable_schema=ON.
-D 2021-03-21T18:23:48.037
+C Merge\schanges\sfrom\sbranch-3.35.\sSpecifically,\sfixes\sfor\sa\srunning\sRBU\swith\sa\scksumvfs\sVFS.
+D 2021-05-11T11:33:44.444
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
-F Makefile.in fe6cc1db11e02b308f3ab0ec2504344697b9eaaa410fa73f48d16a143462e5d3
+F Makefile.in b728d9ef199afe285761e560d8810e7ad4621129c3d47515c484e760d57970d1
 F Makefile.linux-gcc f609543700659711fbd230eced1f01353117621dccae7b9fb70daa64236c5241
-F Makefile.msc 6b5428cef2af1288e02faeb602dabe68fbf2de7bc8a8e29c7299778ee08cd35c
+F Makefile.msc 46c3221d59faccf0502eadd8e6dc69b44f65956b56f88caf74908ccc30010679
 F README.md 1514a365ffca3c138e00c5cc839906108a01011a6b082bad19b09781e3aa498a
-F VERSION 75575cade3e93b31a84ffcb0d40de856a49bd3e4c1028dff52432bfae9806adb
+F VERSION 0c32b05000702ccfdfb5fc72e16b0f965ed664d6cb4fec361196fd0d91eb52c9
 F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
 F art/sqlite370.eps aa97a671332b432a54e1d74ff5e8775be34200c2
 F art/sqlite370.ico af56c1d00fee7cd4753e8631ed60703ed0fc6e90
@@ -34,12 +34,13 @@ F autoconf/tea/win/rules.vc c511f222b80064096b705dbeb97060ee1d6b6d63
 F config.guess 883205ddf25b46f10c181818bf42c09da9888884af96f79e1719264345053bd6
 F config.h.in 6376abec766e9a0785178b1823b5a587e9f1ccbc
 F config.sub c2d0260f17f3e4bc0b6808fccf1b291cb5e9126c14fc5890efc77b9fd0175559
-F configure 174eed3b99edc1c897fe32638c5b4068d4abfb282dc545ccc3ee92a472f73d7a x
+F configure 64b2ab5ac52a8657cfdf97a2a1589441d0deaa859e0d2bbad5ff401829f71676 x
 F configure.ac 4e4b58b32f88c8da9914a2f2c3158f80e69907eccc019fcc7e3ba14ffd91c640
 F contrib/sqlitecon.tcl 210a913ad63f9f991070821e599d600bd913e0ad
 F doc/F2FS.txt c1d4a0ae9711cfe0e1d8b019d154f1c29e0d3abfe820787ba1e9ed7691160fcd
 F doc/lemon.html 1bb72ece6271df0d901d233551dd985f2c6ba30d09382cf2d321ed951ab57491
 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
@@ -291,7 +292,7 @@ F ext/misc/blobio.c a867c4c4617f6ec223a307ebfe0eabb45e0992f74dd47722b96f3e631c0e
 F ext/misc/btreeinfo.c d28ce349b40054eaa9473e835837bad7a71deec33ba13e39f963d50933bfa0f9
 F ext/misc/carray.c b75a0f207391038bf1540d3372f482a95c3613511c7c474db51ede1196321c7c
 F ext/misc/carray.h de74ac70b2338f416723f7d538026e8ec0b7f1d388319f8f140c9a4d7677f02e
-F ext/misc/cksumvfs.c 8dc4e1b718e374bed3a9b5c0a08da2922438002e33267311697768e06217b983
+F ext/misc/cksumvfs.c 2c6b07714f3be6c1200671c53aa781a86d2c472c0fcb2fff520375362eb94303
 F ext/misc/closure.c dbfd8543b2a017ae6b1a5843986b22ddf99ff126ec9634a2f4047cd14c85c243
 F ext/misc/completion.c 6dafd7f4348eecc7be9e920d4b419d1fb2af75d938cd9c59a20cfe8beb2f22b9
 F ext/misc/compress.c 3354c77a7c8e86e07d849916000cdac451ed96500bfb5bd83b20eb61eee012c9
@@ -340,7 +341,7 @@ F ext/misc/wholenumber.c a838d1bea913c514ff316c69695efbb49ea3b8cb37d22afc57f73b6
 F ext/misc/zipfile.c e35e035bc2765b1ccdcb15f9815c2112843fcbc8f36aa071f0e5935df7072228
 F ext/misc/zorder.c b0ff58fa643afa1d846786d51ea8d5c4b6b35aa0254ab5a82617db92f3adda64
 F ext/rbu/rbu.c b880ca5cb857d6d6f52e72eb7397813058ef48c78c5402cd04ff2b6b5437f622
-F ext/rbu/rbu1.test 221d9c18a5e600ac9ac6b1810d99d9f99163a7909ba61597876ab6e4d4beb3d6
+F ext/rbu/rbu1.test c62904bd9526dcdc3496a21199aaf14ae191bbadbf67f076bf16be6b3f2115c2
 F ext/rbu/rbu10.test 0a201c32202143f23c81c0144503da339786fc20acb7a2fda11601b65659f314
 F ext/rbu/rbu11.test 5c834cf491086b45e071eabf71f708febc143e86a384a92de69e0b1a4cace144
 F ext/rbu/rbu12.test 29f8b2118f6c96fac3755bd6d2b55c2db24f878b1f11fbfbe294f3a230a3dcdc
@@ -379,7 +380,7 @@ F ext/rbu/rbuvacuum.test 55e101e90168c2b31df6c9638fe73dc7f7cc666b6142266d1563697
 F ext/rbu/rbuvacuum2.test b8e5b51dc8b2c0153373d024c0936be3f66f9234acbd6d0baab0869d56b14e6b
 F ext/rbu/rbuvacuum3.test 8addd82e4b83b4c93fa47428eae4fd0dbf410f8512c186f38e348feb49ba03dc
 F ext/rbu/rbuvacuum4.test a78898e438a44803eb2bc897ba3323373c9f277418e2d6d76e90f2f1dbccfd10
-F ext/rbu/sqlite3rbu.c e6531884442b72f9e0ba47036fb5c4641ea817ff659a642b3984c10b8535b0fd
+F ext/rbu/sqlite3rbu.c badb52388467f58e67ef104c5276d1ac68b316a30f8ccb2f74eac733625ae236
 F ext/rbu/sqlite3rbu.h 1dc88ab7bd32d0f15890ea08d23476c4198d3da3056985403991f8c9cd389812
 F ext/rbu/test_rbu.c 03f6f177096a5f822d68d8e4069ad8907fe572c62ff2d19b141f59742821828a
 F ext/repair/README.md 92f5e8aae749a4dae14f02eea8e1bb42d4db2b6ce5e83dbcdd6b1446997e0c15
@@ -464,7 +465,7 @@ F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 8273bf49ba3b0c8559cb2774495390c31fd61c60
-F main.mk c6afb1c8bcacc4c3e320ab10259879bc927f0747401e184b64e8f4b78f057ab2
+F main.mk 723543d76167bf302cfc905d0267f6b6a0ab922bf77add04e1099c7766cb056f
 F mkso.sh fd21c06b063bb16a5d25deea1752c2da6ac3ed83
 F mptest/config01.test 3c6adcbc50b991866855f1977ff172eb6d901271
 F mptest/config02.test 4415dfe36c48785f751e16e32c20b077c28ae504
@@ -476,9 +477,9 @@ F spec.template 86a4a43b99ebb3e75e6b9a735d5fd293a24e90ca
 F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
-F src/alter.c 2d631213818b654faaf08755f26e934134c4769757ae9286981401cd6b571081
-F src/analyze.c 01c6c6765cb4d40b473b71d85535093730770bb186f2f473abac25f07fcdee5c
-F src/attach.c 9cbe761e464025694df8e6f6ee4d9f41432c3a255ca9443ccbb4130eeb87cf72
+F src/alter.c 82ed7c15c1ce2a3bebfa33b85865b0ac227f2b2a5944e495a17975904cd3b1d2
+F src/analyze.c 8b522a57784406d75f544e6d67f3fe7a7196702d3d954b7678bb4b4fe789e5a4
+F src/attach.c d176b64d15dfcb08ebd7b11d77cac1d5b08d4ec1e8bd9b59e2f0a84557f95ac9
 F src/auth.c 08954fdc4cc2da5264ba5b75cfd90b67a6fc7d1710a02ccf917c38eadec77853
 F src/backup.c 3014889fa06e20e6adfa0d07b60097eec1f6e5b06671625f476a714d2356513d
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
@@ -486,17 +487,17 @@ F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
 F src/btree.c cfd2a37794532d765e235a2550ad2732924a6d06b07a3bc9f6a71750e3b3cca1
 F src/btree.h 096cc53baa58be22b02c896d1cf933c38cfc6d65f9253c1367ece8cc88a24de5
 F src/btreeInt.h 7bc15a24a02662409ebcd6aeaa1065522d14b7fda71573a2b0568b458f514ae0
-F src/build.c 066c44421bf7b73c6fa47f6fb0c0fcf1357c10552bcf8f3f94c6ebede581cd01
-F src/callback.c d0b853dd413255d2e337b34545e54d888ea02f20da5ad0e63585b389624c4a6c
+F src/build.c 3a2960f823d1c1b8a379cbf9024e5fd45391db95caa7fbe9dd0dc2452ce36b2d
+F src/callback.c d8cdf5d697a31cf54a2b64bce9001fe24f3522a566f44c9fe1eb3a0c7e291c56
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
-F src/ctime.c 2a322b9a3d75771fb4d99e0702851f4f68dda982507a0f798eefb0712969a410
+F src/ctime.c 3552554374bfb39a48f8b0064e11cbcd7f2f5af46bc8136f31f7f79ef3851be5
 F src/date.c e0632f335952b32401482d099321bbf12716b29d6e72836b53ae49683ebae4bf
 F src/dbpage.c 8a01e865bf8bc6d7b1844b4314443a6436c07c3efe1d488ed89e81719047833a
 F src/dbstat.c 3aa79fc3aed7ce906e4ea6c10e85d657299e304f6049861fe300053ac57de36c
 F src/delete.c 73f57a9a183532c344a3135cf8f2a5589376e39183e0b5f562d6b61b2af0f4d8
-F src/expr.c d681f0b48b1e16173ad8e1e8f7323cda120a0c517cb7a3d5b329c4e2c57f18bd
+F src/expr.c cfab1113f9eba24f1d6d11b710577c9fcc9cc8e29ed60bd7ac7906be7481dda4
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
-F src/fkey.c e9063648396c58778f77583a678342fe4a9bc82436bf23c5f9f444f2df0fdaa4
+F src/fkey.c 6dcbab4ead1dbfdc19da70a8650e5734a5124765f75fb840100117a7a45980d2
 F src/func.c 479f6929be027eb0210cbdde9d3529c012facf082d64a6b854a9415940761e5e
 F src/global.c ed55af196a9b66e198aaeda3f5454c3aa7d7d050c6c938181fd044b70d180a81
 F src/hash.c 8d7dda241d0ebdafb6ffdeda3149a412d7df75102cecfc1021c98d6219823b19
@@ -506,7 +507,7 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c e36be69e3810902eaf7e171260c885bc9547b1d41616c868f1cc46e6a0a3b7fd
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 8c9c8cd2bd8eecdb06d9b6e89de7e9e65bae45cc8fc33609cc74023a5c296067
-F src/main.c 2a7ece3a67c646e5fe9984ffe0277d6a76f80ce9715bf2faa591d8cb66b9d913
+F src/main.c 05b648d678f1d4834628b6e76c692f5fa23f4860a0d1205a195944ca73dd2b21
 F src/malloc.c c1af4ac5a463648cd2953fd4ac679b3ba9022ce5ec794a60806150ad69dfd33a
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@ -535,23 +536,23 @@ F src/parse.y 2107aff88e361bbf8388fdede3fed20fda875f23ba7585ec83b20e3e16a95670
 F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 388304fd2d91c39591080b5e0f3c62cfba87db20370e7e0554062bfb29740e9f
-F src/pragma.c eb42cb9bec189cf18cef5d8fcae56e13bb73ef2b019b198fb48740ced81bce95
-F src/pragma.h 8dc78ab7e9ec6ce3ded8332810a2066f1ef6267e2e03cd7356ee00276125c6cf
-F src/prepare.c e21b54489b5c73b06ada15e6fc79b5c6f64b06701924a6ca98944ae59e06256f
+F src/pragma.c 300dcb000f9ac0ac35c913f5e232234275e5007d25147a6915e4ae06b4afd662
+F src/pragma.h ce2b135cde481eeb198af0dfc4781d58528ce80b17580a2b747b8fd4bc969e44
+F src/prepare.c c8797eefce2ae0249ff595c2f3626c4ce88bafe7135e417c4db4db046b0470de
 F src/printf.c 2b03a80d7c11bb422115dca175a18bf430e9c9dbaa0eee63b758f0c022f8f34f
 F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
-F src/resolve.c dd47248c2c914feb0d4428c27d782e2723971d32cfa5536f49306d080df4d45a
+F src/resolve.c fec151c9c33a6fa2e93d10b4e8cd4084a7c773df36fb3ec6788eb89ae493a1a4
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c 734cf12e42f81f2fe461e41214e6552375e55b62a802784a4f0066ac592e7f4a
-F src/shell.c.in aa28256887d049badaf93aa30ab5c76a2ec88143a674d685c0e739056702e5c3
-F src/sqlite.h.in 3426a080ea1f222a73e3bd91e7eacbd30570a0117c03d42c6dde606f33e5e318
+F src/shell.c.in 8f658734fb8b7205c20f6b0bf7d02886887df60000d261f0c0b478511f4b6cd7
+F src/sqlite.h.in 4cb58c05f4483125c961d39989c63448ff34b9460abb9bf8f07234028b851887
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 61b38c073d5e1e96a3d45271b257aef27d0d13da2bea5347692ae579475cd95e
-F src/sqliteInt.h 0f81c7eb3a40dda0b74d0acdc8f3b134346b40be780b1fe5cc24dd294a928d1a
+F src/sqliteInt.h 5cbcb97dd2a283121c59756904a912ab7f484f1755f101936f287ba3f4a45599
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
-F src/status.c 4b8bc2a6905163a38b739854a35b826c737333fab5b1f8e03fa7eb9a4799c4c1
+F src/status.c d0956e57c71160155f620a3efeb1e5c05a3f8b9a897dd09c5263268e5d237579
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
-F src/tclsqlite.c 986b6391f02cd9b53c1d688be55899f6ffddeb8e8014cd83c1b73ff912579a71
+F src/tclsqlite.c f4dd32d001c2be33371dca87e30117352f02dad59a2e5428c97f08703360a169
 F src/test1.c cff43d8e21be543b77651b4d2caf49bd6488fee220f8540ecd9f71d13169dbd1
 F src/test2.c 3efb99ab7f1fc8d154933e02ae1378bac9637da5
 F src/test3.c 61798bb0d38b915067a8c8e03f5a534b431181f802659a6616f9b4ff7d872644
@@ -567,7 +568,7 @@ F src/test_backup.c bf5da90c9926df0a4b941f2d92825a01bbe090a0
 F src/test_bestindex.c 78809f11026f18a93fcfd798d9479cba37e1201c830260bf1edc674b2fa9b857
 F src/test_blob.c ae4a0620b478548afb67963095a7417cd06a4ec0a56adb453542203bfdcb31ce
 F src/test_btree.c 8b2dc8b8848cf3a4db93f11578f075e82252a274
-F src/test_config.c 98698f5242be88af75eaac54adde573471d5ed2f6484e0dac034cb1e763a551a
+F src/test_config.c c7625911811828ba7065c4c789d68a61835f42239d5bd7f4a08aba7c44ccded9
 F src/test_delete.c e2fe07646dff6300b48d49b2fee2fe192ed389e834dd635e3b3bac0ce0bf9f8f
 F src/test_demovfs.c 86142ba864d4297d54c5b2e972e74f3141ae4b30f05b3a95824184ed2d3d7f91
 F src/test_devsym.c aff2255ea290d7718da08af30cdf18e470ff7325a5eff63e0057b1496ed66593
@@ -591,11 +592,12 @@ F src/test_quota.c 6cb9297115b551f433a9ad1741817a9831abed99
 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_server.c a2615049954cbb9cfb4a62e18e2f0616e4dc38fe
 F src/test_sqllog.c 540feaea7280cd5f926168aee9deb1065ae136d0bbbe7361e2ef3541783e187a
 F src/test_superlock.c 4839644b9201da822f181c5bc406c0b2385f672e
 F src/test_syscall.c 1073306ba2e9bfc886771871a13d3de281ed3939
-F src/test_tclsh.c eeafce33ad2136d57e5dec10f1e9a4347447eb72ffd504a1c7b9c6bfe2e71578
+F src/test_tclsh.c 6cbaaf30c4fed76c7b35baa42c521fd225c49563ff580f736d77def9e216b31b
 F src/test_tclvar.c 33ff42149494a39c5fbb0df3d25d6fafb2f668888e41c0688d07273dcb268dfc
 F src/test_thread.c 269ea9e1fa5828dba550eb26f619aa18aedbc29fd92f8a5f6b93521fbb74a61c
 F src/test_vdbecov.c f60c6f135ec42c0de013a1d5136777aa328a776d33277f92abac648930453d43
@@ -606,25 +608,25 @@ F src/test_windirent.h 90dfbe95442c9762357fe128dc7ae3dc199d006de93eb33ba3972e0a9
 F src/test_window.c cdae419fdcea5bad6dcd9368c685abdad6deb59e9fc8b84b153de513d394ba3f
 F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
 F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
-F src/tokenize.c 0b9c82fa628b5adce93e2bcaf935a24d43eb83344fb51551f7835526d0693fc4
+F src/tokenize.c 8cf83b4b95d09c949e2e4d8f99c0f4bcd955436ef28164f4d4b5f334edaca176
 F src/treeview.c c6260e1fa5f41c361b2409edc9b0050bcaef5bc4d6abc467fbc45f0d7ccf3d84
-F src/trigger.c 861c3ec2c5b0fc830bdf82470454a9324fad70cbaa96d2e208fb54577c9e8d28
+F src/trigger.c 1f4c4ad419bf5ef5e7fa13f0df6db89d8b95f38aa29271e1db9281e55d1fb867
 F src/update.c 0f5a61f0787199983530a33f6fffe4f52742f35fcdf6ccfad1078b1a8bc17723
 F src/upsert.c df8f1727d62b5987c4fd302cd4d7c0c84ae57cd65683c5a34a740dfe24039235
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
 F src/util.c 41c7a72da1df47864faa378a1c720b38adb288c6838cb6be5594511b6287a048
-F src/vacuum.c 492422c1463c076473bae1858799c7a0a5fe87a133d1223239447c422cd26286
-F src/vdbe.c 5001a0d3003d3664615dd7ac3cedab1d51e2391b5bdd0878f40a41fdcd942e13
-F src/vdbe.h 25dabb25c7e157b84e59260cfb5b466c3ac103ede9f36f4db371332c47601abe
+F src/vacuum.c 724188c5afbba905b310e8d8e78530956d16e6d60a3ba8a1105d05732d7d8601
+F src/vdbe.c 6d43029157d517ce761c4902d2b543fb8d537dfdd7a8561f95cbe0dd21d4a04d
+F src/vdbe.h bfde0b0f429a0ba4203e5319780a6a1c8b2a809c5cd6baa9ae22e257a657b8b3
 F src/vdbeInt.h 000d9ab1ea4cb55a80de15e28f3f595645b4fddef34bca4347fb3db8031d9041
 F src/vdbeapi.c 4a43e303ec3354c785f453e881521969378e85628278ab74ba4a9df790c0d93b
-F src/vdbeaux.c 1b3eaa3a70d9d1877266e8ade0d0c3b2b4c6cf77d393d94dbcbd522b9bfefc15
-F src/vdbeblob.c 253ed82894924c362a7fa3079551d3554cd1cdace39aa833da77d3bc67e7c1b1
+F src/vdbeaux.c 0e12765d38149f203a8e2dc9a79411df0bfa8c0d066acd3b8125effba8009522
+F src/vdbeblob.c 40028e015fe557a945c99edb6cbf844ea96d853c3e8ac4eb5c1e49bff59f154e
 F src/vdbemem.c 947f2a65910edb4014dc981d33e414a68c51f169f9df8c4c493a0ba840b6eb1f
 F src/vdbesort.c f5b5e473a7cee44e47a94817b042fd7172cf3aa2c0a7928a8339d612bcfdec5a
 F src/vdbetrace.c 666c6fd9f1b62be6999e072a45b913e3c2c3518bc60dfd4d54fe304130acb724
 F src/vdbevtab.c f99b275366c5fc5e2d99f734729880994ab9500bdafde7fae3b02d562b9d323c
-F src/vtab.c 032a0165c147fda16927e6a3230e90c068d4af93f887ce94e26f678fe48e5e4c
+F src/vtab.c b194210339673cf8a60285f1d87ef2a8055eff32782375ffec842fc6bbacc41a
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 69e770e96fd56cc21608992bf2c6f1f3dc5cf2572d0495c6a643b06c3a679f14
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
@@ -632,8 +634,8 @@ F src/walker.c d42d6c80ea363ef689a462e65eefcfe87deab924c50de5baa37ecb6af7d7ddaa
 F src/where.c 10d06b16670a1d2a992d52a9f08e49426d38a08fb0a7ae5f7f62fd023d560e1e
 F src/whereInt.h 446e5e8018f83358ef917cf32d8e6a86dc8430113d0b17e720f1839d3faa44c4
 F src/wherecode.c e57a8690311a75d06e723e8d379f9831de04aba300e07174d236e32a7f9c7a13
-F src/whereexpr.c 53452fe2fb07be2f4cb17f55cc721416fae0092c00717f106faf289c990b6494
-F src/window.c 7e89ac4b6cd6bb9b7772234a625d19c39b530f4ac06e43688a8b7e6a1ab512a2
+F src/whereexpr.c d8cafcf6781cf871082f04d7540862cf0fe30cb381dd1b2145a380376364fe8e
+F src/window.c 32b03808aff2e7263889cce0cbcb2a68efefc2a9d5187514ddb6a2a1046dc7f5
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test ce1aafc86e110685b324e9a763eab4f2a73f737842ec3b687bd965867de90627
 F test/affinity3.test eecb0dabee4b7765a8465439d5e99429279ffba23ca74a7eae270a452799f9e7
@@ -649,7 +651,7 @@ F test/alterauth.test 63442ba61ceb0c1eeb63aac1f4f5cebfa509d352276059d27106ae256b
 F test/alterauth2.test 794ac5cef251819fe364b4fe20f12f86e9c5d68070513c7fd26c17cb244c89af
 F test/altercol.test 3456f7cc4196ef8f7d82d245d6e91940eb12bc95c36c91ac4b512f6b5c9a4fa9
 F test/altercorrupt.test 584d707a80e106952d6382790c8919bcf9f0db678ed3a1c09fd98b7f9d1d3a10
-F test/alterdropcol.test 596623cb8a72d9570bfb8417b0f302810efe007873796f03c17a9e9ff28dade1
+F test/alterdropcol.test 7c5199c930d3db8621672265db0cc05bfa87867bae1ee5362f3cf4eaf36c06ba
 F test/alterdropcol2.test 527fce683b200d620f560f666c44ae33e22728e990a10a48a543280dfd4b4d41
 F test/alterlegacy.test f38c6d06cda39e1f7b955bbce57f2e3ef5b7cb566d3d1234502093e228c15811
 F test/altermalloc.test 167a47de41b5c638f5f5c6efb59784002b196fff70f98d9b4ed3cd74a3fb80c9
@@ -882,7 +884,7 @@ F test/exclusive.test 7ff63be7503990921838d5c9f77f6e33e68e48ed1a9d48cd28745bf650
 F test/exclusive2.test 984090e8e9d1b331d2e8111daf6e5d61dda0bef7
 F test/exec.test e949714dc127eaa5ecc7d723efec1ec27118fdd7
 F test/exists.test 79a75323c78f02bbe9c251ea502a092f9ef63dac
-F test/exists2.test 3e5726d6a67ebd4bd3466db58be424c09156c1f276c7594abb260cbf6ad494d3
+F test/exists2.test 47970f2ce98826519cc38ce502b718641755b30a93d9b89915019ba1e770f361
 F test/existsfault.test 74f7edc713f5a335e7ff47adf503067bf05c6f8630f88b2a19c24f0fa5486ab8
 F test/expr.test 26cd01e8485bc48c8aa6a1add598e9ce1e706b4eb4f3f554e0b0223022e8c2cf
 F test/expr2.test c27327ae9c017a7ff6280123f67aff496f912da74d78c888926d68b46ec75fd8
@@ -1225,7 +1227,7 @@ F test/notify1.test 669b2b743618efdc18ca4b02f45423d5d2304abf
 F test/notify2.test 2ecabaa1305083856b7c39cf32816b612740c161
 F test/notify3.test 10ff25cde502e72a92053a2f215d64bece4ef934
 F test/notnull.test a37b663d5bb728d66fc182016613fb8e4a0a4bbf3d75b8876a7527f7d4ed3f18
-F test/notnull2.test 965a893619751255e59c911a8c58504b3174a3788b1458b7c7365b232209711b
+F test/notnull2.test d5e27e7eb9ff80c587998088a3c40dcc9e4faa71c7ec27a41b4435b0f3b8fdc9
 F test/notnullfault.test 6126e31300632070ca6021698393c7fcf61ab4791bc2aa1d6d704242c0fcd4f8
 F test/null.test b7ff206a1c60fe01aa2abd33ef9ea83c93727d993ca8a613de86e925c9f2bc6f
 F test/nulls1.test 82c5bc33148405f21205865abf13c786084438d573a4ac4e87e11b6091cde526
@@ -1295,7 +1297,14 @@ F test/releasetest.tcl fb76d8fcc95ac29d6356cd9e52b726ab9e43a24082897618dfbcb7c2b
 F test/releasetest_data.tcl 3d41ddb3f04f474ac9d925485da24ce6576ff0ebc4c7201c8a340bc09846c261
 F test/resetdb.test 8062cf10a09d8c048f8de7711e94571c38b38168db0e5877ba7561789e5eeb2b
 F test/resolver01.test f4022acafda7f4d40eca94dbf16bc5fc4ac30ceb
-F test/returning1.test 209b910c132cb2015bb1159f852c7124778004963c09095c42c3d2442110c56c
+F test/returning1.test ce2192b40045cc94d53ac5ec5789a72a3ade233a6ea6e29666e296d151b59479
+F test/reuse1.test faa2ce5ff566d936b8a10d9e22ba2ee66a54ce89fdcf8aef561df6b15b0ff3d3
+F test/reuse2.test 5dd9c98579358f0d5a90d25e36dd6e678a03e23446b6c7f2630a8da22ae7ca94
+F test/reuse3.test 876d15c42d61b1f6ab718cd8169912514ad314d7fe1cd9788080aa62168ba0d1
+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 bc868d57899dc6972e2b4483faae0e03365a0556941474eec487ae21d8d38bb6
 F test/rollbackfault.test 0e646aeab8840c399cfbfa43daab46fd609cf04a
@@ -1336,7 +1345,7 @@ F test/securedel2.test 2d54c28e46eb1fd6902089958b20b1b056c6f1c5
 F test/select1.test 3d23f66bf9ba77570acfe2ca5f1540ece17037cc64ab1a00efec9758ac29c268
 F test/select2.test 352480e0e9c66eda9c3044e412abdf5be0215b56
 F test/select3.test c49fbb758903f3718e2de5aa4655eda4838131cbea24a86db908f8b6889aa68c
-F test/select4.test e8a2502e3623f3058871030599a48abb35789d2244d5b380ecf3696873fdd4a4
+F test/select4.test f0684d3da3bccacbe2a1ebadf6fb49d9df6f53acb4c6ebc228a88d0d6054cc7b
 F test/select5.test df9ec0d218cedceb4fe7b63262025b547b50a55e59148c6f40b60ca25f1d4546
 F test/select6.test 319d45e414cdd321bf17cfacedaf19e3935ad64dac357c53f1492338c6e9b801
 F test/select7.test f659f231489349e8c5734e610803d7654207318f
@@ -1440,7 +1449,7 @@ F test/tabfunc01.test 5ca6d004157a3e886a55a9387b960cc0db41acd88753eb597ff409ec6c
 F test/table.test eb3463b7add9f16a5bb836badf118cf391b809d09fdccd1f79684600d07ec132
 F test/tableapi.test ecbcc29c4ab62c1912c3717c48ea5c5e59f7d64e4a91034e6148bd2b82f177f4
 F test/tableopts.test dba698ba97251017b7c80d738c198d39ab747930
-F test/tclsqlite.test 79a473f5797e317c08f2c4f8192edb3eea6a67329b1087453328b66a7cb31070
+F test/tclsqlite.test 9ad3f8d337ae8e460b25d82094ff1b4f180afc3ca73856ec5a90ac215f43906c
 F test/tempdb.test 4cdaa23ddd8acb4d79cbb1b68ccdfd09b0537aaba909ca69a876157c2a2cbd08
 F test/tempdb2.test 353864e96fd3ae2f70773d0ffbf8b1fe48589b02c2ec05013b540879410c3440
 F test/tempfault.test 0c0d349c9a99bf5f374655742577f8712c647900
@@ -1459,7 +1468,7 @@ F test/thread2.test f35d2106452b77523b3a2b7d1dcde2e5ee8f9e46
 F test/thread_common.tcl 334639cadcb9f912bf82aa73f49efd5282e6cadd
 F test/threadtest1.c 6029d9c5567db28e6dc908a0c63099c3ba6c383b
 F test/threadtest2.c a70a8e94bef23339d34226eb9521015ef99f4df8
-F test/threadtest3.c e63013af10cf236c7610eb06d33bde08c861806dc64be811940ff4d9ddd34a4f
+F test/threadtest3.c e58f0e1b6a3e4ccb24f831650c296e800f6299cc258793f6fc372591f416cb93
 F test/threadtest4.c c1e67136ceb6c7ec8184e56ac61db28f96bd2925
 F test/time-wordcount.sh 8e0b0f8109367827ad5d58f5cc849705731e4b90
 F test/tkt-02a8e81d44.test 6c80d9c7514e2a42d4918bf87bf6bc54f379110c
@@ -1632,12 +1641,13 @@ F test/triggerF.test 5d76f0a8c428ff87a4d5ed52da06f6096a2c787a1e21b846111dfac4123
 F test/triggerG.test 2b816093c91ba73c733cfa8aedcc210ad819d72a98b1da30768a3c56505233e9
 F test/triggerupfrom.test d25961fa70a99b6736193da7b49a36d8c1d28d56188f0be6406d4366315cd6e4
 F test/trustschema1.test 4e970aef0bfe0cee139703cc7209d0e0f07725d999b180ba50770f49edef1494
-F test/tt3_checkpoint.c 9e75cf7c1c364f52e1c47fd0f14c4340a9db0fe1
-F test/tt3_index.c 39eec10a35f57672225be4d182862152896dee4a
-F test/tt3_lookaside1.c 0377e202c3c2a50d688cb65ba203afeda6fafeb9
+F test/tt3_checkpoint.c 9a7fe00e07700af027769d83ef67ab727927ae6c865ecdc71fe8011194200c53
+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 1753f45917699c9c1f66b64c717a717c9379f776
+F test/tt3_stress.c 077e817ac1168443b075fedb44e92db84bb4dc5bd3b6fe1aba25c94ac280b231
+F test/tt3_vacuum.c ca42adcf8a671abbe34338b828464269e21758a6b4857b889dabfd39a3206d98
 F test/types.test bf816ce73c7dfcfe26b700c19f97ef4050d194ff
 F test/types2.test 1aeb81976841a91eef292723649b5c4fe3bc3cac
 F test/types3.test 99e009491a54f4dc02c06bdbc0c5eea56ae3e25a
@@ -1761,7 +1771,7 @@ F test/whereK.test f8e3cf26a8513ecc7f514f54df9f0572c046c42b
 F test/whereL.test 1afe47227f093dc0547236491fb37529b7be9724b8575925a321001b80e6a23a
 F test/wherefault.test 1374c3aa198388925246475f84ad4cd5f9528864
 F test/wherelfault.test 9012e4ef5259058b771606616bd007af5d154e64cc25fa9fd4170f6411db44e3
-F test/wherelimit.test daa0fd9122c5745cc459ec40b8d3c16ce13ce8382b5b847e7cfff4b871260cbf
+F test/wherelimit.test afb46397c6d7e964e6e294ba3569864a0c570fe3807afc634236c2b752372f31
 F test/wherelimit2.test 657a3f24aadee62d058c5091ea682dc4af4b95ffe32f137155be49799a58e721
 F test/win32heap.test 10fd891266bd00af68671e702317726375e5407561d859be1aa04696f2aeee74
 F test/win32lock.test fbf107c91d8f5512be5a5b87c4c42ab9fdd54972
@@ -1780,7 +1790,7 @@ F test/window7.tcl 6a1210f05d40ec89c22960213a22cd3f98d4e2f2eb20646c83c8c30d4d761
 F test/window7.test 1d31276961ae7801edc72173edaf7593e3cbc79c06d1f1f09e20d8418af403cd
 F test/window8.tcl f2711aa3571e4e6b0dad98db8d95fd6cb8d9db0c92bbdf535f153b07606a1ce2
 F test/window8.test c4331b27a6f66d69fa8f8bab10cc731db1a81d293ae108a68f7c3487fa94e65b
-F test/window9.test 4d8c875b73febdbac9b8f2b52ec132b98f48261cdafd6b08db62bc6d8ff913fc
+F test/window9.test 349c71eab4288a1ffc19e2f65872ec2c37e6cf8a1dda2ad300364b7450ae4836
 F test/windowA.test 6d63dc1260daa17141a55007600581778523a8b420629f1282d2acfc36af23be
 F test/windowB.test 6e601f8178ba8ba28b2f19e74fe613815084bb4a8d2ad942defc7d42e191e521
 F test/windowerr.tcl f5acd6fbc210d7b5546c0e879d157888455cd4a17a1d3f28f07c1c8a387019e0
@@ -1843,7 +1853,7 @@ F tool/mkmsvcmin.tcl 6ecab9fe22c2c8de4d82d4c46797bda3d2deac8e763885f5a38d0c44a89
 F tool/mkopcodec.tcl d1b6362bd3aa80d5520d4d6f3765badf01f6c43c
 F tool/mkopcodeh.tcl 352a4319c0ad869eb26442bf7c3b015aa15594c21f1cce5a6420dbe999367c21
 F tool/mkopts.tcl 680f785fdb09729fd9ac50632413da4eadbdf9071535e3f26d03795828ab07fa
-F tool/mkpragmatab.tcl ae5585ae76ca26e4d6ccd5ea9cdebaf5efefb318bf989497a0e846cd711d9ab1
+F tool/mkpragmatab.tcl 37381569b5a5cd3269e3fdbc08829eb1a5f7c2a8e59ee7be8995127e5ef99e0d
 F tool/mkshellc.tcl 70a9978e363b0f3280ca9ce1c46d72563ff479c1930a12a7375e3881b7325712
 F tool/mksourceid.c 36aa8020014aed0836fd13c51d6dc9219b0df1761d6b5f58ff5b616211b079b9
 F tool/mkspeedsql.tcl a1a334d288f7adfe6e996f2e712becf076745c97
@@ -1910,7 +1920,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 71e4da136bd1b5b75a699d69fbaaaec0f9dd1a87e2a9d049a55154892b06647b
-R ae0fc23b03fdb5a4ca6eb2481f79c620
-U drh
-Z 141b5de06b8eca068d7463542c326267
+P 35d1c9a5f846a513a42a0cc9240c3e9a8f3073fa16c88e70b3b9357d8d5adee8 ce8b589e4c7b14ae5f84d47da91931bae109f027490f4b23e0837fde3b037127
+R 54da8ddc61748361e968710a82a15126
+U dan
+Z e72237889cab318d06a88e762bfc81d9

manifest.uuid

@@ -1 +1 @@
-6bb2134027a12801de8e0c73482d94682f902024800a7e426614f65a2fe4f64c
+ca62c36b7f45369679cdc7acfcce108f897d5f7a2ac74bd603b45a024fe5e5bc

src/alter.c

@@ -87,8 +87,8 @@ 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);
   }
 }
 
@@ -1931,33 +1931,44 @@ void sqlite3AlterDropColumn(Parse *pParse, SrcList *pSrc, Token *pName){
     sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite);
     addr = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v);
     reg = ++pParse->nMem;
-    pParse->nMem += pTab->nCol;
     if( HasRowid(pTab) ){
       sqlite3VdbeAddOp2(v, OP_Rowid, iCur, reg);
+      pParse->nMem += pTab->nCol;
     }else{
       pPk = sqlite3PrimaryKeyIndex(pTab);
+      pParse->nMem += pPk->nColumn;
+      for(i=0; i<pPk->nKeyCol; i++){
+        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, reg+i+1);
+      }
+      nField = pPk->nKeyCol;
     }
+    regRec = ++pParse->nMem;
     for(i=0; i<pTab->nCol; i++){
       if( i!=iCol && (pTab->aCol[i].colFlags & COLFLAG_VIRTUAL)==0 ){
         int regOut;
         if( pPk ){
           int iPos = sqlite3TableColumnToIndex(pPk, i);
           int iColPos = sqlite3TableColumnToIndex(pPk, iCol);
+          if( iPos<pPk->nKeyCol ) continue;
           regOut = reg+1+iPos-(iPos>iColPos);
         }else{
           regOut = reg+1+nField;
         }
-        sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, i, regOut);
+        if( i==pTab->iPKey ){
+          sqlite3VdbeAddOp2(v, OP_Null, 0, regOut);
+        }else{
+          sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, i, regOut);
+        }
         nField++;
       }
     }
-    regRec = reg + pTab->nCol;
     sqlite3VdbeAddOp3(v, OP_MakeRecord, reg+1, nField, regRec);
     if( pPk ){
       sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iCur, regRec, reg+1, pPk->nKeyCol);
     }else{
       sqlite3VdbeAddOp3(v, OP_Insert, iCur, regRec, reg);
     }
+    sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
 
     sqlite3VdbeAddOp2(v, OP_Next, iCur, addr+1); VdbeCoverage(v);
     sqlite3VdbeJumpHere(v, addr);

src/analyze.c

@@ -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
         );

src/attach.c

@@ -205,14 +205,14 @@ 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) ){
@@ -312,6 +312,7 @@ static void detachFunc(
     pEntry = sqliteHashNext(pEntry);
   }
 
+  (void)sqlite3SchemaDisconnect(db, i, 0);
   sqlite3BtreeClose(pDb->pBt);
   pDb->pBt = 0;
   pDb->pSchema = 0;

src/build.c

@@ -325,6 +325,39 @@ 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
@@ -350,59 +383,41 @@ 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, &ALT_TEMP_SCHEMA_TABLE[7])==0
-         || sqlite3StrICmp(zName+7, &ALT_SCHEMA_TABLE[7])==0
-         || sqlite3StrICmp(zName+7, &DFLT_SCHEMA_TABLE[7])==0
-        ){
-          p = sqlite3HashFind(&db->aDb[1].pSchema->tblHash, 
-                              DFLT_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, &ALT_SCHEMA_TABLE[7])==0 ){
-          p = sqlite3HashFind(&db->aDb[i].pSchema->tblHash,
-                              DFLT_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, ALT_SCHEMA_TABLE)==0 ){
+      zName = DFLT_SCHEMA_TABLE;
+      continue;
     }
-    if( p==0 && sqlite3StrNICmp(zName, "sqlite_", 7)==0 ){
-      if( sqlite3StrICmp(zName+7, &ALT_SCHEMA_TABLE[7])==0 ){
-        p = sqlite3HashFind(&db->aDb[0].pSchema->tblHash, DFLT_SCHEMA_TABLE);
-      }else if( sqlite3StrICmp(zName+7, &ALT_TEMP_SCHEMA_TABLE[7])==0 ){
-        p = sqlite3HashFind(&db->aDb[1].pSchema->tblHash, 
-                            DFLT_TEMP_SCHEMA_TABLE);
-      }
+    if( sqlite3StrICmp(zName, ALT_TEMP_SCHEMA_TABLE)==0 ){
+      zName = DFLT_TEMP_SCHEMA_TABLE;
+      continue;
     }
+    if( sqlite3StrICmp(zName, DFLT_SCHEMA_TABLE)!=0 ) break;
+    if( sqlite3_stricmp(zDatabase, db->aDb[1].zDbSName)!=0 ) break;
+    zName = DFLT_TEMP_SCHEMA_TABLE;
   }
-  return p;
+  return 0;
 }
 
 /*
@@ -427,6 +442,7 @@ 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;
@@ -443,8 +459,18 @@ Table *sqlite3LocateTable(
       if( pMod==0 && sqlite3_strnicmp(zName, "pragma_", 7)==0 ){
         pMod = sqlite3PragmaVtabRegister(db, zName);
       }
-      if( pMod && sqlite3VtabEponymousTableInit(pParse, pMod) ){
-        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++;
+        }
+        if( sqlite3VtabEponymousTableInit(pParse, pMod) ){
+          Table *pEpoTab = pMod->pEpoTab;
+          assert( IsSharedSchema(db) || pEpoTab->pSchema==db->aDb[0].pSchema );
+          pEpoTab->pSchema = db->aDb[0].pSchema;  /* For SHARED_SCHEMA mode */
+          return pEpoTab;
+        }
       }
     }
 #endif
@@ -454,7 +480,7 @@ 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);
@@ -613,11 +639,10 @@ 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);
       }
     }
   }
@@ -630,16 +655,17 @@ 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);
@@ -1135,7 +1161,7 @@ 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);
@@ -2641,7 +2667,7 @@ 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);
   }
 
@@ -3171,7 +3197,7 @@ 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]);
@@ -3183,6 +3209,7 @@ 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.
@@ -3631,7 +3658,7 @@ 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) ){
@@ -4127,7 +4154,7 @@ 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);
       }
@@ -4276,6 +4303,7 @@ 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;

src/callback.c

@@ -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->magic!=SQLITE_MAGIC_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.
@@ -513,15 +570,317 @@ 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);

src/ctime.c

@@ -301,6 +301,9 @@ static const char * const sqlite3azCompileOpt[] = {
 #if SQLITE_ENABLE_SESSION
   "ENABLE_SESSION",
 #endif
+#if SQLITE_ENABLE_SHARED_SCHEMA
+  "ENABLE_SHARED_SCHEMA",
+#endif
 #if SQLITE_ENABLE_SNAPSHOT
   "ENABLE_SNAPSHOT",
 #endif

src/expr.c

@@ -958,8 +958,8 @@ Expr *sqlite3ExprAnd(Parse *pParse, Expr *pLeft, Expr *pRight){
   }else if( (ExprAlwaysFalse(pLeft) || ExprAlwaysFalse(pRight)) 
          && !IN_RENAME_OBJECT
   ){
-    sqlite3ExprDelete(db, pLeft);
-    sqlite3ExprDelete(db, pRight);
+    sqlite3ExprDeferredDelete(pParse, pLeft);
+    sqlite3ExprDeferredDelete(pParse, pRight);
     return sqlite3Expr(db, TK_INTEGER, "0");
   }else{
     return sqlite3PExpr(pParse, TK_AND, pLeft, pRight);
@@ -1156,6 +1156,22 @@ void sqlite3ExprDelete(sqlite3 *db, Expr *p){
   if( p ) sqlite3ExprDeleteNN(db, p);
 }
 
+
+/*
+** Arrange to cause pExpr to be deleted when the pParse is deleted.
+** This is similar to sqlite3ExprDelete() except that the delete is
+** deferred untilthe pParse is deleted.
+**
+** The pExpr might be deleted immediately on an OOM error.
+**
+** The deferred delete is (currently) implemented by adding the
+** pExpr to the pParse->pConstExpr list with a register number of 0.
+*/
+void sqlite3ExprDeferredDelete(Parse *pParse, Expr *pExpr){
+  pParse->pConstExpr = 
+      sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+}
+
 /* Invoke sqlite3RenameExprUnmap() and sqlite3ExprDelete() on the
 ** expression.
 */
@@ -5781,8 +5797,7 @@ static int agginfoPersistExprCb(Walker *pWalker, Expr *pExpr){
         pExpr = sqlite3ExprDup(db, pExpr, 0);
         if( pExpr ){
           pAggInfo->aCol[iAgg].pCExpr = pExpr;
-          pParse->pConstExpr = 
-             sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+          sqlite3ExprDeferredDelete(pParse, pExpr);
         }
       }
     }else{
@@ -5791,8 +5806,7 @@ static int agginfoPersistExprCb(Walker *pWalker, Expr *pExpr){
         pExpr = sqlite3ExprDup(db, pExpr, 0);
         if( pExpr ){
           pAggInfo->aFunc[iAgg].pFExpr = pExpr;
-          pParse->pConstExpr = 
-             sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+          sqlite3ExprDeferredDelete(pParse, pExpr);
         }
       }
     }

src/fkey.c

@@ -1416,9 +1416,9 @@ void sqlite3FkDelete(sqlite3 *db, Table *pTab){
   FKey *pFKey;                    /* Iterator variable */
   FKey *pNext;                    /* Copy of pFKey->pNextFrom */
 
-  assert( db==0 || IsVirtual(pTab)
-         || sqlite3SchemaMutexHeld(db, 0, pTab->pSchema) );
   for(pFKey=pTab->pFKey; pFKey; pFKey=pNext){
+    assert( db==0 || IsVirtual(pTab)
+         || sqlite3SchemaMutexHeld(db, 0, pTab->pSchema) );
 
     /* Remove the FK from the fkeyHash hash table. */
     if( !db || db->pnBytesFreed==0 ){

src/main.c

@@ -1159,6 +1159,17 @@ 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);
@@ -1327,6 +1338,7 @@ void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
       sqlite3BtreeClose(pDb->pBt);
       pDb->pBt = 0;
       if( j!=1 ){
+        sqlite3SchemaDisconnect(db, j, 0);
         pDb->pSchema = 0;
       }
     }
@@ -3683,7 +3695,7 @@ 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;
@@ -3693,7 +3705,7 @@ 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 ){
@@ -3703,14 +3715,29 @@ 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 || pTab->pSelect ){
     pTab = 0;
     goto error_out;
@@ -3783,6 +3810,7 @@ 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;
 }

src/pragma.c

@@ -471,7 +471,13 @@ 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 */
@@ -1905,9 +1911,10 @@ 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 */

src/pragma.h

@@ -55,12 +55,19 @@
 #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
@@ -155,7 +162,7 @@ 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
@@ -176,7 +183,7 @@ 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
@@ -237,21 +244,21 @@ 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",
   /* ePragTyp:  */ PragTyp_DATABASE_LIST,
-  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_Result0|PragFlg_OneSchema,
   /* ColNames:  */ 41, 3,
   /* iArg:      */ 0 },
 #endif
 #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:  */ 49, 1,
   /* iArg:      */ 0 },
 #endif
@@ -288,7 +295,7 @@ 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
@@ -304,9 +311,9 @@ 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",
@@ -346,7 +353,7 @@ 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
@@ -377,7 +384,7 @@ 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",
@@ -415,7 +422,7 @@ 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",
@@ -443,7 +450,7 @@ 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",
@@ -542,14 +549,14 @@ 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:  */ 27, 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
@@ -633,7 +640,7 @@ static const PragmaName aPragmaName[] = {
   /* iArg:      */ 0 },
  {/* zName:     */ "wal_checkpoint",
   /* ePragTyp:  */ PragTyp_WAL_CHECKPOINT,
-  /* ePragFlg:  */ PragFlg_NeedSchema,
+  /* ePragFlg:  */ PragFlg_NeedSchema|PragFlg_OneSchema,
   /* ColNames:  */ 44, 3,
   /* iArg:      */ 0 },
 #endif

src/prepare.c

@@ -38,6 +38,11 @@ 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] : "?";
@@ -48,6 +53,28 @@ 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.
@@ -71,6 +98,15 @@ 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 */
+);
 
 
 /*
@@ -136,7 +172,11 @@ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
     db->init.orphanTrigger = 0;
     db->init.azInit = 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;
@@ -148,7 +188,12 @@ 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 
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+               && (rc&0xFF)!=SQLITE_LOCKED 
+               && (rc&0xFF)!=SQLITE_IOERR
+#endif
+        ){
           corruptSchema(pData, argv, sqlite3_errmsg(db));
         }
       }
@@ -178,6 +223,12 @@ 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;
 }
 
@@ -205,10 +256,28 @@ 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
@@ -229,6 +298,7 @@ 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;
@@ -239,7 +309,6 @@ 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);
@@ -394,6 +463,10 @@ 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.
@@ -415,6 +488,35 @@ 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
@@ -425,8 +527,12 @@ 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) );
@@ -436,20 +542,19 @@ 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;
 }
 
 /*
@@ -461,11 +566,12 @@ 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;
     }
   }
@@ -491,6 +597,10 @@ 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. */
@@ -780,6 +890,7 @@ static int sqlite3LockAndPrepare(
 ){
   int rc;
   int cnt = 0;
+  int bReleaseSchema = 0;
 
 #ifdef SQLITE_ENABLE_API_ARMOR
   if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
@@ -789,6 +900,7 @@ 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
@@ -798,7 +910,11 @@ static int sqlite3LockAndPrepare(
     assert( rc==SQLITE_OK || *ppStmt==0 );
   }while( rc==SQLITE_ERROR_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;

src/resolve.c

@@ -376,15 +376,19 @@ static int lookupName(
       if( pParse->pTriggerTab!=0 ){
         int op = pParse->eTriggerOp;
         assert( op==TK_DELETE || op==TK_UPDATE || op==TK_INSERT );
-        if( op!=TK_DELETE && zTab && sqlite3StrICmp("new",zTab) == 0 ){
+        if( pParse->bReturning ){
+          if( (pNC->ncFlags & NC_UBaseReg)!=0
+           && (zTab==0 || sqlite3StrICmp(zTab,pParse->pTriggerTab->zName)==0)
+          ){
+            pExpr->iTable = op!=TK_DELETE;
+            pTab = pParse->pTriggerTab;
+          }
+        }else if( op!=TK_DELETE && zTab && sqlite3StrICmp("new",zTab) == 0 ){
           pExpr->iTable = 1;
           pTab = pParse->pTriggerTab;
         }else if( op!=TK_INSERT && zTab && sqlite3StrICmp("old",zTab)==0 ){
           pExpr->iTable = 0;
           pTab = pParse->pTriggerTab;
-        }else if( pParse->bReturning && (pNC->ncFlags & NC_UBaseReg)!=0 ){
-          pExpr->iTable = op!=TK_DELETE;
-          pTab = pParse->pTriggerTab;
         }
       }
 #endif /* SQLITE_OMIT_TRIGGER */

src/shell.c.in

@@ -1152,13 +1152,14 @@ struct 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
 */
@@ -4054,6 +4055,12 @@ 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
 #ifndef SQLITE_NOHAVE_SYSTEM
   ".shell CMD ARGS...       Run CMD ARGS... in a system shell",
 #endif
@@ -4590,6 +4597,11 @@ static void open_db(ShellState *p, int openFlags){
             SQLITE_OPEN_READONLY|p->openFlags, 0);
         break;
       }
+      case SHELL_OPEN_SHAREDSCHEMA: {
+        sqlite3_open_v2(p->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(p->zDbFilename, &p->db,
@@ -6783,6 +6795,237 @@ static char *shellMPrintf(int *pRc, const char *zFmt, ...){
   }
   return z;
 }
+static int sharedSchemaFix(ShellState *pState, const char *zDb, int eFix){
+  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], eFix);
+      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;
+}
 
 /*
 ** When running the ".recover" command, each output table, and the special
@@ -8710,6 +8953,8 @@ static int do_meta_command(char *zLine, ShellState *p){
         p->openMode = SHELL_OPEN_APPENDVFS;
       }else if( optionMatch(z, "readonly") ){
         p->openMode = SHELL_OPEN_READONLY;
+      }else if( optionMatch(z, "sharedschema") ){
+        p->openMode = SHELL_OPEN_SHAREDSCHEMA;
       }else if( optionMatch(z, "nofollow") ){
         p->openFlags |= SQLITE_OPEN_NOFOLLOW;
 #ifdef SQLITE_ENABLE_DESERIALIZE
@@ -9728,6 +9973,13 @@ 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
+
 #ifndef SQLITE_NOHAVE_SYSTEM
   if( c=='s'
    && (strncmp(azArg[0], "shell", n)==0 || strncmp(azArg[0],"system",n)==0)
@@ -11058,6 +11310,8 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
 #endif
     }else if( strcmp(z,"-readonly")==0 ){
       data.openMode = SHELL_OPEN_READONLY;
+    }else if( strcmp(z,"-sharedschema")==0 ){
+      data.openMode = SHELL_OPEN_SHAREDSCHEMA;
     }else if( strcmp(z,"-nofollow")==0 ){
       data.openFlags = SQLITE_OPEN_NOFOLLOW;
 #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_HAVE_ZLIB)
@@ -11175,6 +11429,8 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
 #endif
     }else if( strcmp(z,"-readonly")==0 ){
       data.openMode = SHELL_OPEN_READONLY;
+    }else if( strcmp(z,"-sharedschema")==0 ){
+      data.openMode = SHELL_OPEN_SHAREDSCHEMA;
     }else if( strcmp(z,"-nofollow")==0 ){
       data.openFlags |= SQLITE_OPEN_NOFOLLOW;
     }else if( strcmp(z,"-ascii")==0 ){

src/sqlite.h.in

@@ -574,10 +574,11 @@ int sqlite3_exec(
 #define SQLITE_OPEN_NOFOLLOW         0x01000000  /* Ok for sqlite3_open_v2() */
 
 /* 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
 **
@@ -1128,6 +1129,10 @@ struct sqlite3_io_methods {
 ** file to the database file, but before the *-shm file is updated to
 ** record the fact that the pages have been checkpointed.
 ** </ul>
+**
+** <li>[[SQLITE_FCNTL_CKSM_FILE]]
+** Used by the cksmvfs VFS module only.
+** </ul>
 */
 #define SQLITE_FCNTL_LOCKSTATE               1
 #define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
@@ -1167,6 +1172,8 @@ struct sqlite3_io_methods {
 #define SQLITE_FCNTL_CKPT_DONE              37
 #define SQLITE_FCNTL_RESERVE_BYTES          38
 #define SQLITE_FCNTL_CKPT_START             39
+#define SQLITE_FCNTL_EXTERNAL_READER        40
+#define SQLITE_FCNTL_CKSM_FILE              41
 
 /* deprecated names */
 #define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE

src/sqliteInt.h

@@ -1141,6 +1141,7 @@ 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;
@@ -1277,6 +1278,10 @@ 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
 };
 
 /*
@@ -1308,6 +1313,9 @@ 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
 };
 
 /*
@@ -1631,6 +1639,12 @@ 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.
 */
@@ -1711,6 +1725,9 @@ 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
@@ -2164,6 +2181,9 @@ 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
@@ -3454,7 +3474,6 @@ struct Parse {
   AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
   Parse *pToplevel;    /* Parse structure for main program (or NULL) */
   Table *pTriggerTab;  /* Table triggers are being coded for */
-  Parse *pParentParse; /* Parent parser if this parser is nested */
   union {
     int addrCrTab;         /* Address of OP_CreateBtree on CREATE TABLE */
     Returning *pReturning; /* The RETURNING clause */
@@ -3621,6 +3640,9 @@ 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
 };
 
 /*
@@ -3732,6 +3754,7 @@ 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;
 
@@ -4290,6 +4313,7 @@ Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*, int);
 void sqlite3ExprFunctionUsable(Parse*,Expr*,FuncDef*);
 void sqlite3ExprAssignVarNumber(Parse*, Expr*, u32);
 void sqlite3ExprDelete(sqlite3*, Expr*);
+void sqlite3ExprDeferredDelete(Parse*, Expr*);
 void sqlite3ExprUnmapAndDelete(Parse*, Expr*);
 ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
 ExprList *sqlite3ExprListAppendVector(Parse*,ExprList*,IdList*,Expr*);
@@ -4796,6 +4820,29 @@ 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)
+# 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);

src/status.c

@@ -288,11 +288,24 @@ 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;
       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;
 
@@ -314,7 +327,14 @@ 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;
       sqlite3BtreeLeaveAll(db);
 

src/tclsqlite.c

@@ -3666,6 +3666,9 @@ 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;
 }
@@ -3797,6 +3800,16 @@ 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;

src/test_config.c

@@ -770,6 +770,12 @@ 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), \

src/test_schemapool.c

@@ -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;
+}
+

src/test_tclsh.c

@@ -77,6 +77,7 @@ 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);

src/tokenize.c

@@ -564,6 +564,7 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   int lastTokenParsed = -1;       /* type of the previous token */
   sqlite3 *db = pParse->db;       /* The database connection */
   int mxSqlLen;                   /* Max length of an SQL string */
+  Parse *pParentParse = db->pParse;
 #ifdef sqlite3Parser_ENGINEALWAYSONSTACK
   yyParser sEngine;    /* Space to hold the Lemon-generated Parser object */
 #endif
@@ -599,7 +600,6 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   assert( pParse->pNewTrigger==0 );
   assert( pParse->nVar==0 );
   assert( pParse->pVList==0 );
-  pParse->pParentParse = db->pParse;
   db->pParse = pParse;
   while( 1 ){
     n = sqlite3GetToken((u8*)zSql, &tokenType);
@@ -714,8 +714,7 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
     sqlite3DeleteTrigger(db, pParse->pNewTrigger);
   }
   sqlite3DbFree(db, pParse->pVList);
-  db->pParse = pParse->pParentParse;
-  pParse->pParentParse = 0;
+  db->pParse = pParentParse;
   assert( nErr==0 || pParse->rc!=SQLITE_OK );
   return nErr;
 }

src/trigger.c

@@ -62,11 +62,26 @@ Trigger *sqlite3TriggerList(Parse *pParse, Table *pTab){
   }
   pList = pTab->pTrigger;
   if( pTmpSchema!=pTab->pSchema ){
+    sqlite3 *db = pParse->db;
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+    char *zSchema = 0;
+    if( IsSharedSchema(db) ){
+      zSchema = db->aDb[sqlite3SchemaToIndex(db, pTab->pSchema)].zDbSName;
+    }
+#endif
+    assert( sqlite3SchemaMutexHeld(db, 0, pTmpSchema) );
     while( p ){
       Trigger *pTrig = (Trigger *)sqliteHashData(p);
+#ifdef SQLITE_ENABLE_SHARED_SCHEMA
+      if( ( (zSchema==0 && pTrig->pTabSchema==pTab->pSchema)
+         || (zSchema!=0 && 0==sqlite3StrICmp(pTrig->zTabSchema, zSchema)) 
+          ) && 0==sqlite3StrICmp(pTrig->table, pTab->zName)
+      ){
+#else 
       if( pTrig->pTabSchema==pTab->pSchema
        && 0==sqlite3StrICmp(pTrig->table, pTab->zName)
       ){
+#endif
         pTrig->pNext = pList;
         pList = pTrig;
       }else if( pTrig->op==TK_RETURNING ){
@@ -249,6 +264,12 @@ 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;
@@ -355,7 +376,7 @@ 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);
   }
 
@@ -573,6 +594,9 @@ 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);
@@ -644,6 +668,7 @@ 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
@@ -823,6 +848,25 @@ SrcList *sqlite3TriggerStepSrc(
   return pSrc;
 }
 
+/*
+** Return true if the pExpr term from the RETURNING clause argument
+** list is of the form "*".  Raise an error if the terms if of the
+** form "table.*".
+*/
+static int isAsteriskTerm(
+  Parse *pParse,      /* Parsing context */
+  Expr *pTerm         /* A term in the RETURNING clause */
+){
+  assert( pTerm!=0 );
+  if( pTerm->op==TK_ASTERISK ) return 1;
+  if( pTerm->op!=TK_DOT ) return 0;
+  assert( pTerm->pRight!=0 );
+  assert( pTerm->pLeft!=0 );
+  if( pTerm->pRight->op!=TK_ASTERISK ) return 0;
+  sqlite3ErrorMsg(pParse, "RETURNING may not use \"TABLE.*\" wildcards");
+  return 1;
+}
+
 /* The input list pList is the list of result set terms from a RETURNING
 ** clause.  The table that we are returning from is pTab.
 **
@@ -840,7 +884,8 @@ static ExprList *sqlite3ExpandReturning(
 
   for(i=0; i<pList->nExpr; i++){
     Expr *pOldExpr = pList->a[i].pExpr;
-    if( ALWAYS(pOldExpr!=0) && pOldExpr->op==TK_ASTERISK ){
+    if( NEVER(pOldExpr==0) ) continue;
+    if( isAsteriskTerm(pParse, pOldExpr) ){
       int jj;
       for(jj=0; jj<pTab->nCol; jj++){
         Expr *pNewExpr;
@@ -1068,7 +1113,9 @@ static TriggerPrg *codeRowTrigger(
   Parse *pSubParse;           /* Parse context for sub-vdbe */
   int iEndTrigger = 0;        /* Label to jump to if WHEN is false */
 
-  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
+  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger)
+       || IsSharedSchema(pParse->db)
+  );
   assert( pTop->pVdbe );
 
   /* Allocate the TriggerPrg and SubProgram objects. To ensure that they
@@ -1176,7 +1223,9 @@ static TriggerPrg *getRowTrigger(
   Parse *pRoot = sqlite3ParseToplevel(pParse);
   TriggerPrg *pPrg;
 
-  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) );
+  assert( pTrigger->zName==0 || pTab==tableOfTrigger(pTrigger) 
+       || IsSharedSchema(pParse->db)
+  );
 
   /* 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

src/vacuum.c

@@ -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);

src/vdbe.c

@@ -3559,13 +3559,6 @@ case OP_Transaction: {
    && (iMeta!=pOp->p3
       || db->aDb[pOp->p1].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.
@@ -3582,6 +3575,13 @@ 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;
   }

src/vdbe.h

@@ -223,7 +223,7 @@ 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);

src/vdbeaux.c

@@ -471,8 +471,10 @@ 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);

src/vdbeblob.c

@@ -131,7 +131,9 @@ int sqlite3_blob_open(
   char *zErr = 0;
   Table *pTab;
   Incrblob *pBlob = 0;
+  Parse *pParentParse = db->pParse;
   Parse sParse;
+  int bUnlock;            /* True to unlock reusable schemas before returning */
 
 #ifdef SQLITE_ENABLE_API_ARMOR
   if( ppBlob==0 ){
@@ -148,11 +150,13 @@ int sqlite3_blob_open(
 
   sqlite3_mutex_enter(db->mutex);
 
+  bUnlock = sqlite3LockReusableSchema(db);
   pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
   do {
     memset(&sParse, 0, sizeof(Parse));
     if( !pBlob ) goto blob_open_out;
     sParse.db = db;
+    db->pParse = &sParse;
     sqlite3DbFree(db, zErr);
     zErr = 0;
 
@@ -331,6 +335,8 @@ int sqlite3_blob_open(
   } while( (++nAttempt)<SQLITE_MAX_SCHEMA_RETRY && rc==SQLITE_SCHEMA );
 
 blob_open_out:
+  db->pParse = pParentParse;
+  sqlite3UnlockReusableSchema(db, bUnlock);
   if( rc==SQLITE_OK && db->mallocFailed==0 ){
     *ppBlob = (sqlite3_blob *)pBlob;
   }else{

src/vtab.c

@@ -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->pVTable; pVtab && pVtab->db!=db; pVtab=pVtab->pNext);
   return pVtab;
 }
@@ -489,7 +507,7 @@ 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;
@@ -563,6 +581,7 @@ static int vtabCallConstructor(
   char *zModuleName;
   int iDb;
   VtabCtx *pCtx;
+  int nByte;                      /* Bytes of space to allocate */
 
   /* Check that the virtual-table is not already being initialized */
   for(pCtx=db->pVtabCtx; pCtx; pCtx=pCtx->pPrior){
@@ -579,7 +598,11 @@ 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);
@@ -587,6 +610,10 @@ 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);
@@ -629,12 +656,22 @@ 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->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.  */
-      pVTable->pNext = pTab->pVTable;
-      pTab->pVTable = pVTable;
+      ** into the linked list headed by pTab->pVTable. 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 */
+      {
+        pVTable->pNext = pTab->pVTable;
+        pTab->pVTable = pVTable;
+      }
 
       for(iCol=0; iCol<pTab->nCol; iCol++){
         char *zType = sqlite3ColumnType(&pTab->aCol[iCol], "");
@@ -688,6 +725,7 @@ int sqlite3VtabCallConnect(Parse *pParse, Table *pTab){
 
   assert( pTab );
   if( !IsVirtual(pTab) || sqlite3GetVTable(db, pTab) ){
+    assert( !IsVirtual(pTab) || pTab->nCol>0 );
     return SQLITE_OK;
   }
 

src/whereexpr.c

@@ -511,6 +511,7 @@ static void whereCombineDisjuncts(
   int op;                /* Operator for the combined expression */
   int idxNew;            /* Index in pWC of the next virtual term */
 
+  if( (pOne->wtFlags | pTwo->wtFlags) & TERM_VNULL ) return;
   if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
   if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
   if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
@@ -1216,6 +1217,7 @@ static void exprAnalyzeExists(
 #endif
   if( pSel->pPrior ) return;
   if( pSel->pWhere==0 ) return;
+  if( pSel->pLimit ) return;
   if( 0==exprAnalyzeExistsFindEq(pSel, 0, 0) ) return;
 
   pDup = sqlite3ExprDup(db, pExpr, 0);

src/window.c

@@ -1469,6 +1469,7 @@ static void windowCheckValue(Parse *pParse, int reg, int eCond){
     VdbeCoverageIf(v, eCond==2);
   }
   sqlite3VdbeAddOp3(v, aOp[eCond], regZero, sqlite3VdbeCurrentAddr(v)+2, reg);
+  sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC);
   VdbeCoverageNeverNullIf(v, eCond==0); /* NULL case captured by */
   VdbeCoverageNeverNullIf(v, eCond==1); /*   the OP_MustBeInt */
   VdbeCoverageNeverNullIf(v, eCond==2);

test/alterdropcol.test

@@ -276,4 +276,44 @@ do_catchsql_test 6.1 {
   ALTER TABLE t2 DROP COLUMN z;
 } {1 {database disk image is malformed}}
 
+# 2021-04-06 dbsqlfuzz crash-331c5c29bb76257b198f1318eef3288f9624c8ce
+reset_db
+do_execsql_test 7.0 {
+  CREATE TABLE t1(a, b, c, PRIMARY KEY(a COLLATE nocase, a)) WITHOUT ROWID;
+  INSERT INTO t1 VALUES(1, 2, 3);
+  INSERT INTO t1 VALUES(4, 5, 6);
+}
+do_execsql_test 7.1 {
+  ALTER TABLE t1 DROP COLUMN c;                
+}
+do_execsql_test 7.2 {
+  SELECT sql FROM sqlite_schema;
+} {{CREATE TABLE t1(a, b, PRIMARY KEY(a COLLATE nocase, a)) WITHOUT ROWID}}
+do_execsql_test 7.3 {
+  SELECT * FROM t1;
+} {1 2 4 5}
+
+foreach {tn wo} {
+  1 {}
+  2 {WITHOUT ROWID}
+} {
+  reset_db
+  do_execsql_test 9.$tn.0 "
+    CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c) $wo;
+  "
+  do_execsql_test 9.$tn.1 {
+    WITH s(i) AS (
+        SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<50000
+    )
+    INSERT INTO t1(a, b, c) SELECT i, 123, 456 FROM s;
+  }
+  do_execsql_test 9.$tn.2 {
+    ALTER TABLE t1 DROP COLUMN b;
+  }
+
+  do_execsql_test 9.$tn.3 {
+    SELECT count(*), c FROM t1 GROUP BY c;
+  } {50000 456}
+}
+
 finish_test

test/exists2.test

@@ -164,6 +164,12 @@ do_execsql_test 2.7a {
   four one
 }
 
+do_execsql_test 2.7b {
+  SELECT a FROM t3 WHERE EXISTS (SELECT 1 FROM t4 WHERE (a,x)=(c,y) LIMIT 1)
+} {
+  four one
+}
+
 # EXISTS clauses using vector expressions in the WHERE clause.
 #
 reset_db

test/notnull2.test

@@ -97,5 +97,17 @@ do_execsql_test 2.1 {
   SELECT * FROM (SELECT a, b FROM t1) LEFT JOIN t3 ON a IS NULL;
 }
 
+
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE t0(c0 PRIMARY KEY);
+  INSERT INTO t0(c0) VALUES (0);
+}
+do_execsql_test 3.1 {
+  SELECT * FROM t0 WHERE ((c0 NOT NULL) AND 1) OR (c0 == NULL);
+} {0}
+
 finish_test
 

test/returning1.test

@@ -115,5 +115,74 @@ do_execsql_test 5.5 {
   UPDATE t2 SET b='123' WHERE b='abc' RETURNING (SELECT b FROM t1);
 } {123}
 
+# Ticket 132994c8b1063bfb
+reset_db
+do_catchsql_test 6.0 {
+  CREATE TABLE t1(id INTEGER PRIMARY KEY);
+  CREATE TABLE t2(x INT, y INT);
+  INSERT INTO t1 VALUES(1),(2),(4),(9);
+  INSERT INTO t2 VALUES(3,7), (4,25), (5,99);
+  UPDATE t1 SET id=id+y FROM t2 WHERE t1.id=t2.x RETURNING t2.*;
+} {1 {RETURNING may not use "TABLE.*" wildcards}}
+do_catchsql_test 6.1 {
+  UPDATE t1 SET id=id+y FROM t2 WHERE t1.id=t2.x RETURNING *, '|';
+  SELECT * FROM t1 ORDER BY id;
+} {0 {29 | 1 2 9 29}}
+
+# Forum https://sqlite.org/forum/forumpost/85aef8bc01
+# Do not silently ignore nonsense table names in the RETURNING clause.
+# Raise an error.
+#
+reset_db
+do_execsql_test 7.1 {
+  CREATE TABLE t1(a INT, b INT);
+  CREATE TABLE t2(x INT, y INT);
+  INSERT INTO t1(a,b) VALUES(1,2);
+  INSERT INTO t2(x,y) VALUES(1,30);
+} {}
+do_catchsql_test 7.2 {
+  UPDATE t1 SET b=b+1 RETURNING new.b;
+} {1 {no such column: new.b}}
+do_catchsql_test 7.3 {
+  UPDATE t1 SET b=b+1 RETURNING old.b;
+} {1 {no such column: old.b}}
+do_catchsql_test 7.4 {
+  UPDATE t1 SET b=b+1 RETURNING another.b;
+} {1 {no such column: another.b}}
+do_catchsql_test 7.5 {
+  UPDATE t1 SET b=b+y FROM t2 WHERE t2.x=t1.a RETURNING t2.x;
+} {1 {no such column: t2.x}}
+do_catchsql_test 7.6 {
+  UPDATE t1 SET b=b+y FROM t2 WHERE t2.x=t1.a RETURNING t1.b;
+} {0 32}
+
+# This is goofy:  The RETURNING clause does not honor the alias
+# for the table being modified.  This might change in the future.
+#
+do_catchsql_test 7.7 {
+  UPDATE t1 AS alias SET b=123 RETURNING alias.b;
+} {1 {no such column: alias.b}}
+do_catchsql_test 7.8 {
+  UPDATE t1 AS alias SET b=alias.b+1000 RETURNING t1.b;
+} {0 1032}
+
+# Forum: https://sqlite.org/forum/info/34c81d83c9177f46
+reset_db
+do_execsql_test 8.1 {
+  CREATE TABLE t1(a);
+  CREATE TABLE t2(b,c);
+  INSERT INTO t1 VALUES(1);
+  INSERT INTO t2 VALUES(3,40);
+} {}
+do_catchsql_test 8.2 {
+  INSERT INTO t1 VALUES(3) RETURNING a, (SELECT c FROM t2 WHERE new.a=t2.b) AS x;
+} {1 {no such column: new.a}}
+do_catchsql_test 8.3 {
+  INSERT INTO t1 VALUES(3) RETURNING a, (SELECT c FROM t2 WHERE old.a=t2.b) AS x;
+} {1 {no such column: old.a}}
+do_catchsql_test 8.4 {
+  INSERT INTO t1 VALUES(3) RETURNING a, (SELECT c FROM t2 WHERE t1.a=t2.b) AS x;
+} {0 {3 40}}
+
 finish_test
 

test/reuse1.test

@@ -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
+
+

test/reuse2.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;
+} {}
+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=1 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=2 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=6 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
+

test/reuse3.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 {vtable constructor failed: schemapool}}
+
+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 && $N2==0)
+} {1}
+
+do_test 6.3 {
+  execsql { SELECT * FROM main.t1 }
+  set N1 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  set N2 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
+  expr {$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
+

test/reuse4.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
+

test/reuse5.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
+

test/reuse6.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
+

test/reusefault.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
+

test/select4.test

@@ -1025,5 +1025,19 @@ do_execsql_test select4-18.3 {
    WHERE abs(z1.aa)=z2.aa AND z1.aa=123;
 } {123}
 
+# 2021-03-31 Fix an assert() problem in the logic at the end of sqlite3Select()
+# that validates AggInfo.  The checks to ensure that AggInfo.aCol[].pCExpr
+# references a valid expression was looking at an expression that had been
+# deleted by the truth optimization in sqlite3ExprAnd() which was invoked by
+# the push-down optimization.  This is harmless in delivery builds, as that code
+# only runs with SQLITE_DEBUG.  But it should still be fixed.  The problem
+# was discovered by dbsqlfuzz (crash-dece7b67a3552ed7e571a7bda903afd1f7bd9b21)
+#
+reset_db
+do_execsql_test select4-19.1 {
+  CREATE TABLE t1(x);
+  INSERT INTO t1 VALUES(99);
+  SELECT sum((SELECT 1 FROM (SELECT 2 WHERE x IS NULL) WHERE 0)) FROM t1;
+} {{}}
 
 finish_test

test/tclsqlite.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?"
 }

test/threadtest3.c

@@ -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 */
@@ -520,11 +520,14 @@ 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 ){
@@ -926,7 +929,7 @@ 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)",
@@ -965,7 +968,7 @@ 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) ){
     usleep(500*1000);
     execsql(&err, &db, "PRAGMA wal_checkpoint");
@@ -984,7 +987,7 @@ 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);"
@@ -1017,7 +1020,7 @@ 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);
@@ -1047,7 +1050,7 @@ 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);
 
@@ -1067,7 +1070,7 @@ 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;
@@ -1104,7 +1107,7 @@ 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);"
@@ -1127,7 +1130,7 @@ 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);
   }
@@ -1142,7 +1145,7 @@ 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(
@@ -1162,7 +1165,7 @@ 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);"
@@ -1182,7 +1185,7 @@ 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);
 
@@ -1195,7 +1198,7 @@ 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;"
@@ -1286,7 +1289,7 @@ 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;"
@@ -1315,7 +1318,7 @@ 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;
 
@@ -1368,7 +1371,7 @@ 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;
@@ -1393,7 +1396,7 @@ 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;"
@@ -1433,6 +1436,7 @@ 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){
@@ -1458,6 +1462,7 @@ 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 };

test/tt3_checkpoint.c

@@ -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;"

test/tt3_index.c

@@ -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) "

test/tt3_lookaside1.c

@@ -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 ("

test/tt3_reuseschema.c

@@ -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);
+}

test/tt3_stress.c

@@ -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);"

test/tt3_vacuum.c

@@ -23,7 +23,7 @@
 static char *vacuum1_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);
   i64 i = 0;
 
   while( !timetostop(&err) ){
@@ -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);"

test/wherelimit.test

@@ -237,8 +237,8 @@ ifcapable {update_delete_limit} {
   } {11}
   create_test_data 6
   do_test wherelimit-3.2 {
-    execsql {UPDATE t1 SET y=1 WHERE x=1 RETURNING x, old.y, '|' LIMIT 5}
-  } {1 1 | 1 2 | 1 3 | 1 4 | 1 5 |}
+    execsql {UPDATE t1 SET y=1 WHERE x=1 RETURNING x, y, '|' LIMIT 5}
+  } {1 1 | 1 1 | 1 1 | 1 1 | 1 1 |}
   do_test wherelimit-3.2cnt {
     execsql {SELECT count(*) FROM t1 WHERE y=1}
   } {10}

test/window9.test

@@ -265,4 +265,21 @@ do_execsql_test 8.4 {
   FROM v1;
 } {0.0 0.0}
 
+#--------------------------------------------------------------------------
+reset_db
+do_execsql_test 9.0 {
+  CREATE TABLE t1(a, b, c);
+  INSERT INTO t1 VALUES(NULL,'bb',356);
+  INSERT INTO t1 VALUES('CB','aa',158);
+  INSERT INTO t1 VALUES('BB','aa',399);
+  INSERT INTO t1 VALUES('FF','bb',938);
+}
+
+do_catchsql_test 9.1 {
+  SELECT sum(c) OVER (
+    ORDER BY c RANGE BETWEEN 0 PRECEDING AND '-700' PRECEDING
+  )
+  FROM t1
+} {1 {frame ending offset must be a non-negative number}}
+
 finish_test

tool/mkpragmatab.tcl

@@ -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
@@ -232,7 +232,7 @@ 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)
 
@@ -256,7 +256,7 @@ set pragma_def {
   IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
 
   NAME: database_list
-  FLAG: NeedSchema Result0
+  FLAG: NeedSchema Result0 OneSchema
   COLS: seq name file
   IF:   !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
 
@@ -284,7 +284,7 @@ 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)
 
@@ -330,14 +330,14 @@ 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
@@ -351,7 +351,7 @@ 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)
 
@@ -510,6 +510,12 @@ 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} {