Begin a series of changes designed to reduce the scope and frequency of

invalidating schemas.  Design goals are that the internal schema should
never be deleted out from under a prepared statement that is running and
that all prepared statements should be expired if the schema is invalidated.
At the same time, minimize the number of schema invalidations.  This change
merely revises the sqlite3ResetInternalSchema() function to use -1 as the
wildcard for "all" rather than 0, so that we can reset the main schema
independently of all the others.

FossilOrigin-Name: 6a8ad6e31e0d2b8a5ace38faf0efd805155ee5f3

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\srace\scondition\sin\sOP_ParseSchema.
-D 2011-04-02T09:44:43
+C Begin\sa\sseries\sof\schanges\sdesigned\sto\sreduce\sthe\sscope\sand\sfrequency\sof\ninvalidating\sschemas.\s\sDesign\sgoals\sare\sthat\sthe\sinternal\sschema\sshould\nnever\sbe\sdeleted\sout\sfrom\sunder\sa\sprepared\sstatement\sthat\sis\srunning\sand\nthat\sall\sprepared\sstatements\sshould\sbe\sexpired\sif\sthe\sschema\sis\sinvalidated.\nAt\sthe\ssame\stime,\sminimize\sthe\snumber\sof\sschema\sinvalidations.\s\sThis\schange\nmerely\srevises\sthe\ssqlite3ResetInternalSchema()\sfunction\sto\suse\s-1\sas\sthe\nwildcard\sfor\s"all"\srather\sthan\s0,\sso\sthat\swe\scan\sreset\sthe\smain\sschema\nindependently\sof\sall\sthe\sothers.
+D 2011-04-02T16:28:52.034
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 7a4d9524721d40ef9ee26f93f9bd6a51dba106f2
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -116,15 +116,15 @@ F sqlite3.1 6be1ad09113570e1fc8dcaff84c9b0b337db5ffc
 F sqlite3.pc.in ae6f59a76e862f5c561eb32a380228a02afc3cad
 F src/alter.c 280f5c04b11b492703a342222b3de0a999445280
 F src/analyze.c d0a673d303f611690fc7a3293aaefed57cccc5c8
-F src/attach.c 438ea6f6b5d5961c1f49b737f2ce0f14ce7c6877
+F src/attach.c 7cae2cf0c14762ce14c074a860ec52890a973a56
 F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
-F src/backup.c 537f89c7ef5021cb580f31f782e556ffffcb2ed1
+F src/backup.c b7529a6691f0fd534ae8ff622203c46a7f1b626b
 F src/bitvec.c af50f1c8c0ff54d6bdb7a80e2fceca5a93670bef
 F src/btmutex.c 96a12f50f7a17475155971a241d85ec5171573ff
 F src/btree.c 2b9c81ff64da339a67dda4f94c0d763627be0b67
 F src/btree.h 8d36f774ec4b1d0027b8966f8c03d9a72a518c14
 F src/btreeInt.h 20f73dc93b1eeb83afd7259fbc6bd7dcf2df7fe4
-F src/build.c 6c490fe14dedb094a202f559e3b29a276abffcf8
+F src/build.c 9dca3dc000b85753cff822c69151f88d913f3b3e
 F src/callback.c 5069f224882cbdccd559f591271d28d7f37745bc
 F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
 F src/ctime.c 52ff72f966cee3087e0138a3ec69371c22be3c01
@@ -143,7 +143,7 @@ F src/journal.c 552839e54d1bf76fb8f7abe51868b66acacf6a0e
 F src/legacy.c a199d7683d60cef73089e892409113e69c23a99f
 F src/lempar.c 7f026423f4d71d989e719a743f98a1cbd4e6d99e
 F src/loadext.c 8af9fcc75708d60b88636ccba38b4a7b3c155c3e
-F src/main.c c23c62e53d120c5eee086c0e2cc96cc9a691c50e
+F src/main.c 14c019b381b76ea378ee8629d1ed861a3899e075
 F src/malloc.c 92d59a007d7a42857d4e9454aa25b6b703286be1
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 00bd8265c81abb665c48fea1e0c234eb3b922206
@@ -170,8 +170,8 @@ F src/parse.y 12b7ebd61ea54f0e1b1083ff69cc2c8ce9353d58
 F src/pcache.c 09d38c44ab275db581f7a2f6ff8b9bc7f8c0faaa
 F src/pcache.h c683390d50f856d4cd8e24342ae62027d1bb6050
 F src/pcache1.c d548e31beafa792d1994b663a29a5303569efc4e
-F src/pragma.c 4221eb822d7cdb1fb69be555b189e15e5a24b6b5
-F src/prepare.c eb4944d9f7bfa13eb42a7416ed9aaed4de4d0bf3
+F src/pragma.c 672c5e453d6321fdcfd76ffe346d99cae54fcddb
+F src/prepare.c cec63cb151fcaeee00006ec5376698310caea56a
 F src/printf.c 585a36b6a963df832cfb69505afa3a34ed5ef8a1
 F src/random.c cd4a67b3953b88019f8cd4ccd81394a8ddfaba50
 F src/resolve.c 1c0f32b64f8e3f555fe1f732f9d6f501a7f05706
@@ -234,16 +234,16 @@ F src/trigger.c ec4813709e990a169b6923293e839fa5dfd64282
 F src/update.c 81911be16ece3c3e7716aa18565b4814ec41f8b9
 F src/utf.c d83650c3ea08f7407bd9d0839d9885241c209c60
 F src/util.c cd997077bad039efc0597eb027c929658f93c018
-F src/vacuum.c 924bd1bcee2dfb05376f79845bd3b4cec7b54b2f
-F src/vdbe.c a45a6a0daf2161797d50b3b5b8a3e0e4debf2d2b
+F src/vacuum.c 3b2b0998f4f277e4bc61469c2d78d8424d02899b
+F src/vdbe.c 6b15a8fb9bb5d5abd232fbc72cc6410c2fd70c1b
 F src/vdbe.h 4de0efb4b0fdaaa900cf419b35c458933ef1c6d2
 F src/vdbeInt.h e1c6254641168507d25b46affb6dfb53c782f553
 F src/vdbeapi.c a09ad9164cafc505250d5dd6b69660c960f1308c
-F src/vdbeaux.c 77921792f7ebae267490816deb6a9488f938fa85
+F src/vdbeaux.c e97565fb2fea822a2e853370c440b493ef09d7e7
 F src/vdbeblob.c c3ccb7c8732858c680f442932e66ad06bb036562
 F src/vdbemem.c 0498796b6ffbe45e32960d6a1f5adfb6e419883b
 F src/vdbetrace.c 3ba13bc32bdf16d2bdea523245fd16736bed67b5
-F src/vtab.c e1edca38c4c4310710635bb91bb3c87fdf60f21d
+F src/vtab.c 341ae69e949ce583c1729b0177f62ab821e8b42f
 F src/wal.c 7334009b396285b658a95a3b6bc6d2b016a1f794
 F src/wal.h 7a5fbb00114b7f2cd40c7e1003d4c41ce9d26840
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
@@ -926,7 +926,11 @@ F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/split-sqlite3c.tcl d9be87f1c340285a3e081eb19b4a247981ed290c
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 20afd81a4cf4d23962ec841bbd375f36a5156fb6
-R 25d34b3e2efbdd1c8e0ceadec6512306
-U dan
-Z 659aea6fa897bf521b0a686e5d197299
+P 71a799b02a3b3cf2e12758dea29fd2465bbec3e1
+R 5fca8a4df9fe5cb6d589b9d60d83b4fc
+T *bgcolor * #d3a8bc
+T *branch * schema-parse-refactor
+T *sym-schema-parse-refactor *
+T -sym-trunk *
+U drh
+Z 80e5b841d301ef316c4772ca966c9795

manifest.uuid

@@ -1 +1 @@
-71a799b02a3b3cf2e12758dea29fd2465bbec3e1
+6a8ad6e31e0d2b8a5ace38faf0efd805155ee5f3

src/attach.c

@@ -200,7 +200,7 @@ static void attachFunc(
       db->aDb[iDb].pBt = 0;
       db->aDb[iDb].pSchema = 0;
     }
-    sqlite3ResetInternalSchema(db, 0);
+    sqlite3ResetInternalSchema(db, -1);
     db->nDb = iDb;
     if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
       db->mallocFailed = 1;
@@ -272,7 +272,7 @@ static void detachFunc(
   sqlite3BtreeClose(pDb->pBt);
   pDb->pBt = 0;
   pDb->pSchema = 0;
-  sqlite3ResetInternalSchema(db, 0);
+  sqlite3ResetInternalSchema(db, -1);
   return;
 
 detach_error:

src/backup.c

@@ -401,7 +401,7 @@ int sqlite3_backup_step(sqlite3_backup *p, int nPage){
       int nDestTruncate;
   
       if( p->pDestDb ){
-        sqlite3ResetInternalSchema(p->pDestDb, 0);
+        sqlite3ResetInternalSchema(p->pDestDb, -1);
       }
 
       /* Set nDestTruncate to the final number of pages in the destination

src/build.c

@@ -393,26 +393,34 @@ void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){
 ** if there were schema changes during the transaction or if a
 ** schema-cookie mismatch occurs.
 **
-** If iDb==0 then reset the internal schema tables for all database
-** files.  If iDb>=1 then reset the internal schema for only the
+** If iDb<0 then reset the internal schema tables for all database
+** files.  If iDb>=0 then reset the internal schema for only the
 ** single file indicated.
 */
 void sqlite3ResetInternalSchema(sqlite3 *db, int iDb){
   int i, j;
-  assert( iDb>=0 && iDb<db->nDb );
+  assert( iDb<db->nDb );
 
-  if( iDb==0 ){
-    sqlite3BtreeEnterAll(db);
+  if( iDb>=0 ){
+    /* Case 1:  Reset the single schema identified by iDb */
+    Db *pDb = &db->aDb[iDb];
+    if( pDb->pSchema ){
+      assert(iDb==1 || (pDb->pBt && sqlite3BtreeHoldsMutex(pDb->pBt)));
+      sqlite3SchemaFree(pDb->pSchema);
+    }
+    return;
   }
-  for(i=iDb; i<db->nDb; i++){
+  /* Case 2 (from here to the end): Reset all schemas for all attached
+  ** databases. */
+  assert( iDb<0 );
+  sqlite3BtreeEnterAll(db);
+  for(i=0; i<db->nDb; i++){
     Db *pDb = &db->aDb[i];
     if( pDb->pSchema ){
       assert(i==1 || (pDb->pBt && sqlite3BtreeHoldsMutex(pDb->pBt)));
       sqlite3SchemaFree(pDb->pSchema);
     }
-    if( iDb>0 ) return;
   }
-  assert( iDb==0 );
   db->flags &= ~SQLITE_InternChanges;
   sqlite3VtabUnlockList(db);
   sqlite3BtreeLeaveAll(db);

src/main.c

@@ -687,7 +687,7 @@ int sqlite3_close(sqlite3 *db){
   }
   sqlite3_mutex_enter(db->mutex);
 
-  sqlite3ResetInternalSchema(db, 0);
+  sqlite3ResetInternalSchema(db, -1);
 
   /* If a transaction is open, the ResetInternalSchema() call above
   ** will not have called the xDisconnect() method on any virtual
@@ -730,7 +730,7 @@ int sqlite3_close(sqlite3 *db){
       }
     }
   }
-  sqlite3ResetInternalSchema(db, 0);
+  sqlite3ResetInternalSchema(db, -1);
 
   /* Tell the code in notify.c that the connection no longer holds any
   ** locks and does not require any further unlock-notify callbacks.
@@ -821,7 +821,7 @@ void sqlite3RollbackAll(sqlite3 *db){
 
   if( db->flags&SQLITE_InternChanges ){
     sqlite3ExpirePreparedStatements(db);
-    sqlite3ResetInternalSchema(db, 0);
+    sqlite3ResetInternalSchema(db, -1);
   }
 
   /* Any deferred constraint violations have now been resolved. */

src/pragma.c

@@ -115,7 +115,7 @@ static int invalidateTempStorage(Parse *pParse){
     }
     sqlite3BtreeClose(db->aDb[1].pBt);
     db->aDb[1].pBt = 0;
-    sqlite3ResetInternalSchema(db, 0);
+    sqlite3ResetInternalSchema(db, -1);
   }
   return SQLITE_OK;
 }

src/prepare.c

@@ -338,7 +338,7 @@ static int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){
   }
   if( db->mallocFailed ){
     rc = SQLITE_NOMEM;
-    sqlite3ResetInternalSchema(db, 0);
+    sqlite3ResetInternalSchema(db, -1);
   }
   if( rc==SQLITE_OK || (db->flags&SQLITE_RecoveryMode)){
     /* Black magic: If the SQLITE_RecoveryMode flag is set, then consider
@@ -613,7 +613,7 @@ static int sqlite3Prepare(
     schemaIsValid(pParse);
   }
   if( pParse->rc==SQLITE_SCHEMA ){
-    sqlite3ResetInternalSchema(db, 0);
+    sqlite3ResetInternalSchema(db, -1);
   }
   if( db->mallocFailed ){
     pParse->rc = SQLITE_NOMEM;

src/vacuum.c

@@ -335,8 +335,9 @@ end_of_vacuum:
     pDb->pSchema = 0;
   }
 
-  sqlite3ResetInternalSchema(db, 0);
+  sqlite3ResetInternalSchema(db, -1);
 
   return rc;
 }
+
 #endif  /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */

src/vdbe.c

@@ -2649,7 +2649,7 @@ case OP_Savepoint: {
         }
         if( p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
           sqlite3ExpirePreparedStatements(db);
-          sqlite3ResetInternalSchema(db, 0);
+          sqlite3ResetInternalSchema(db, -1);
           db->flags = (db->flags | SQLITE_InternChanges);
         }
       }
@@ -5946,7 +5946,7 @@ vdbe_error_halt:
   sqlite3VdbeHalt(p);
   if( rc==SQLITE_IOERR_NOMEM ) db->mallocFailed = 1;
   rc = SQLITE_ERROR;
-  if( resetSchemaOnFault ) sqlite3ResetInternalSchema(db, 0);
+  if( resetSchemaOnFault ) sqlite3ResetInternalSchema(db, -1);
 
   /* This is the only way out of this procedure.  We have to
   ** release the mutexes on btrees that were acquired at the

src/vdbeaux.c

@@ -2191,7 +2191,7 @@ int sqlite3VdbeHalt(Vdbe *p){
   
     /* Rollback or commit any schema changes that occurred. */
     if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){
-      sqlite3ResetInternalSchema(db, 0);
+      sqlite3ResetInternalSchema(db, -1);
       db->flags = (db->flags | SQLITE_InternChanges);
     }
 

src/vtab.c

@@ -48,7 +48,7 @@ static int createModule(
     if( pDel==pMod ){
       db->mallocFailed = 1;
     }
-    sqlite3ResetInternalSchema(db, 0);
+    sqlite3ResetInternalSchema(db, -1);
   }else if( xDestroy ){
     xDestroy(pAux);
   }