Merge recent trunk enhancements into the bloom-filter branch.

FossilOrigin-Name: 11d97fb8be6b5155f38df130d7e828edd0f381e32f651458939b1cb9cb973fff

manifest

@@ -1,5 +1,5 @@
-C Merge\strunk\sfixes\sinto\sthe\sbloom-filter\sbranch.
+C Merge\srecent\strunk\senhancements\sinto\sthe\sbloom-filter\sbranch.
-D 2021-12-01T21:07:05.915
+D 2021-12-03T16:02:05.551
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -491,10 +491,10 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c 3014889fa06e20e6adfa0d07b60097eec1f6e5b06671625f476a714d2356513d
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 13b965a0f3cd57221e3b4e61e24452ec264a5b163de347b03b5039ddcd95cd54
+F src/btree.c 81feddbcc60d524518a7afc713b6dab0ad7caadb7370433f117c8c557dcdc889
 F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
 F src/btreeInt.h ee9348c4cb9077243b049edc93a82c1f32ca48baeabf2140d41362b9f9139ff7
-F src/build.c 179b11b07484497052096d88b953b9a6c22cbb0c23ba75c4347e9a99dae4a6c0
+F src/build.c 70759481a346322934332485381805c9ba9442bbe7959bf40bdc14140c832517
 F src/callback.c 106b585da1edd57d75fa579d823a5218e0bf37f191dbf7417eeb4a8a9a267dbc
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 8159d5f706551861c18ec6c8f6bdf105e15ea00367f05d9ab65d31a1077facc1
@@ -539,7 +539,7 @@ F src/os_win.c 77d39873836f1831a9b0b91894fec45ab0e9ca8e067dc8c549e1d1eca1566fe9
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c bc10c191d18bffd3d76eda5f162799e43a9f875ecfe7c4869f752e2ddef87ea2
 F src/pager.h 4bf9b3213a4b2bebbced5eaa8b219cf25d4a82f385d093cd64b7e93e5285f66f
-F src/parse.y 0bd7971a7489bbf6c3726f1b50da6e508bdff8fa493e9cc3f5a96b12cbb2361e
+F src/parse.y 761b5d30a7ea9bd2db3b3571438cfcceb5f7dbf4fcad6881c8de65bdda07135a
 F src/pcache.c 084e638432c610f95aea72b8509f0845d2791293f39d1b82f0c0a7e089c3bb6b
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 54881292a9a5db202b2c0ac541c5e3ef9a5e8c4f1c1383adb2601d5499a60e65
@@ -551,7 +551,7 @@ F src/random.c 097dc8b31b8fba5a9aca1697aeb9fd82078ec91be734c16bffda620ced7ab83c
 F src/resolve.c 4a1db4aadd802683db40ca2dbbb268187bd195f10cbdb7206dbd8ac988795571
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c a7a3d9f54eb24821ec5f67f2e5589b68a5d42d46fc5849d7376886777d93a85a
-F src/shell.c.in 975f268ef261773fcbed1e519dfa10c4f33e8b1cffc12120563e61857fff07c6
+F src/shell.c.in e7ee6517544d075d9f06ee2571567026b89cf9fbeef16a74918019b1cb425764
 F src/sqlite.h.in 5cd209ac7dc4180f0e19292846f40440b8488015849ca0110c70b906b57d68f0
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 8ff2fd2c166150b2e48639f5e506fb44e29f1a3f65031710b9e89d1c126ac839
@@ -637,10 +637,10 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c ed0398a7adf02c31e34aada42cc86c58f413a7afe5f741a5d373ad087abde028
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c 1b8a6c53c34c59c765190484d245c457bedc211325de4c75a2070432fd67e314
+F src/where.c c04c4108028513cf2f264505f2bc3e861c2ed96985d7a5feead4cf76fe057dc1
-F src/whereInt.h 23f990791dc428f0bbb31f8ef5026b78b6290272de86185f4822c85f4c774803
+F src/whereInt.h 83ae6f7d0fce8b5164d97698790e0005a909b3d06d73df86a4a6bb0d9411861e
 F src/wherecode.c 620e81077588a727876a86f87aab310c02fc4e4960691e48153d8a87ca1fa453
-F src/whereexpr.c 17bdbf4f5b490e70a18635498f0b910a558f953a9bf80af7f19cbde6e60e6825
+F src/whereexpr.c 19394cb463003e9cc9305730b1508b8817a22bb7247170d81234b691a7f05b89
 F src/window.c 5d3b397b0c026d0ff5890244ac41359e524c01ae31e78782e1ff418c3e271a9e
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test ce1aafc86e110685b324e9a763eab4f2a73f737842ec3b687bd965867de90627
@@ -1933,7 +1933,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 50ac4de1d7cbb586ea7969e1ae80ea8b021e194edc2fa7db19374b4ee9369bee a818ba2ed635b91e279dde44236fc7446a33db2b46c9409b67021248c01bf4e5
+P 0864bfbf079a98beaa484911edb17c3dc728e78eca231d4247b282fd824cc098 8029e6bab508bf0b8ec1df00a829c5d4de2a84d66dc56b9ff03da879ceef7788
-R 890b5445e197091ccaaa040621e42f1c
+R 62eaa6fad42f4285b48b7186b5cb4970
 U drh
-Z bba2c27b0261227719d25ee9783d113a
+Z 2d614121b81c56be6760e2166ceb6c54

manifest.uuid

@@ -1 +1 @@
-0864bfbf079a98beaa484911edb17c3dc728e78eca231d4247b282fd824cc098
+11d97fb8be6b5155f38df130d7e828edd0f381e32f651458939b1cb9cb973fff

src/btree.c

@@ -2693,30 +2693,38 @@ static int removeFromSharingList(BtShared *pBt){
 ** MX_CELL_SIZE(pBt) bytes with a 4-byte prefix for a left-child
 ** pointer.
 */
-static void allocateTempSpace(BtShared *pBt){
+static SQLITE_NOINLINE int allocateTempSpace(BtShared *pBt){
-  if( !pBt->pTmpSpace ){
+  assert( pBt!=0 );
-    pBt->pTmpSpace = sqlite3PageMalloc( pBt->pageSize );
+  assert( pBt->pTmpSpace==0 );
-
+  /* This routine is called only by btreeCursor() when allocating the
-    /* One of the uses of pBt->pTmpSpace is to format cells before
+  ** first write cursor for the BtShared object */
-    ** inserting them into a leaf page (function fillInCell()). If
+  assert( pBt->pCursor!=0 && (pBt->pCursor->curFlags & BTCF_WriteFlag)!=0 );
-    ** a cell is less than 4 bytes in size, it is rounded up to 4 bytes
+  pBt->pTmpSpace = sqlite3PageMalloc( pBt->pageSize );
-    ** by the various routines that manipulate binary cells. Which
+  if( pBt->pTmpSpace==0 ){
-    ** can mean that fillInCell() only initializes the first 2 or 3
+    BtCursor *pCur = pBt->pCursor;
-    ** bytes of pTmpSpace, but that the first 4 bytes are copied from
+    pBt->pCursor = pCur->pNext;  /* Unlink the cursor */
-    ** it into a database page. This is not actually a problem, but it
+    memset(pCur, 0, sizeof(*pCur));
-    ** does cause a valgrind error when the 1 or 2 bytes of unitialized 
+    return SQLITE_NOMEM_BKPT;
-    ** data is passed to system call write(). So to avoid this error,
-    ** zero the first 4 bytes of temp space here.
-    **
-    ** Also:  Provide four bytes of initialized space before the
-    ** beginning of pTmpSpace as an area available to prepend the
-    ** left-child pointer to the beginning of a cell.
-    */
-    if( pBt->pTmpSpace ){
-      memset(pBt->pTmpSpace, 0, 8);
-      pBt->pTmpSpace += 4;
-    }
   }
+
+  /* One of the uses of pBt->pTmpSpace is to format cells before
+  ** inserting them into a leaf page (function fillInCell()). If
+  ** a cell is less than 4 bytes in size, it is rounded up to 4 bytes
+  ** by the various routines that manipulate binary cells. Which
+  ** can mean that fillInCell() only initializes the first 2 or 3
+  ** bytes of pTmpSpace, but that the first 4 bytes are copied from
+  ** it into a database page. This is not actually a problem, but it
+  ** does cause a valgrind error when the 1 or 2 bytes of unitialized 
+  ** data is passed to system call write(). So to avoid this error,
+  ** zero the first 4 bytes of temp space here.
+  **
+  ** Also:  Provide four bytes of initialized space before the
+  ** beginning of pTmpSpace as an area available to prepend the
+  ** left-child pointer to the beginning of a cell.
+  */
+  memset(pBt->pTmpSpace, 0, 8);
+  pBt->pTmpSpace += 4;
+  return SQLITE_OK;
 }
 
 /*
@@ -4457,10 +4465,6 @@ static int btreeCursor(
   assert( pBt->pPage1 && pBt->pPage1->aData );
   assert( wrFlag==0 || (pBt->btsFlags & BTS_READ_ONLY)==0 );
 
-  if( wrFlag ){
-    allocateTempSpace(pBt);
-    if( pBt->pTmpSpace==0 ) return SQLITE_NOMEM_BKPT;
-  }
   if( iTable<=1 ){
     if( iTable<1 ){
       return SQLITE_CORRUPT_BKPT;
@@ -4477,19 +4481,25 @@ static int btreeCursor(
   pCur->pKeyInfo = pKeyInfo;
   pCur->pBtree = p;
   pCur->pBt = pBt;
-  pCur->curFlags = wrFlag ? BTCF_WriteFlag : 0;
+  pCur->curFlags = 0;
-  pCur->curPagerFlags = wrFlag ? 0 : PAGER_GET_READONLY;
   /* If there are two or more cursors on the same btree, then all such
   ** cursors *must* have the BTCF_Multiple flag set. */
   for(pX=pBt->pCursor; pX; pX=pX->pNext){
     if( pX->pgnoRoot==iTable ){
       pX->curFlags |= BTCF_Multiple;
-      pCur->curFlags |= BTCF_Multiple;
+      pCur->curFlags = BTCF_Multiple;
     }
   }
+  pCur->eState = CURSOR_INVALID;
   pCur->pNext = pBt->pCursor;
   pBt->pCursor = pCur;
-  pCur->eState = CURSOR_INVALID;
+  if( wrFlag ){
+    pCur->curFlags |= BTCF_WriteFlag;
+    pCur->curPagerFlags = 0;
+    if( pBt->pTmpSpace==0 ) return allocateTempSpace(pBt);
+  }else{
+    pCur->curPagerFlags = PAGER_GET_READONLY;
+  }
   return SQLITE_OK;
 }
 static int btreeCursorWithLock(

src/build.c

@@ -4406,13 +4406,13 @@ void sqlite3CreateIndex(
       /* Add an entry in sqlite_schema for this index
       */
       sqlite3NestedParse(pParse, 
-          "INSERT INTO %Q." LEGACY_SCHEMA_TABLE " VALUES('index',%Q,%Q,#%d,%Q);",
+         "INSERT INTO %Q." LEGACY_SCHEMA_TABLE " VALUES('index',%Q,%Q,#%d,%Q);",
-          db->aDb[iDb].zDbSName,
+         db->aDb[iDb].zDbSName,
-          pIndex->zName,
+         pIndex->zName,
-          pTab->zName,
+         pTab->zName,
-          iMem,
+         iMem,
-          zStmt
+         zStmt
-          );
+      );
       sqlite3DbFree(db, zStmt);
 
       /* Fill the index with data and reparse the schema. Code an OP_Expire

src/parse.y

@@ -236,7 +236,7 @@ columnname(A) ::= nm(A) typetoken(Y). {sqlite3AddColumn(pParse,A,Y);}
 //
 %token ABORT ACTION AFTER ANALYZE ASC ATTACH BEFORE BEGIN BY CASCADE CAST.
 %token CONFLICT DATABASE DEFERRED DESC DETACH EACH END EXCLUSIVE EXPLAIN FAIL.
-%token OR AND NOT IS MATCH LIKE_KW BETWEEN IN ISNULL NOTNULL NE EQ.
+%token OR AND NOT MATCH LIKE_KW BETWEEN IS IN ISNULL NOTNULL NE EQ.
 %token GT LE LT GE ESCAPE.
 
 // The following directive causes tokens ABORT, AFTER, ASC, etc. to

src/shell.c.in

@@ -8941,16 +8941,8 @@ static int do_meta_command(char *zLine, ShellState *p){
     char *zNewFilename = 0;  /* Name of the database file to open */
     int iName = 1;           /* Index in azArg[] of the filename */
     int newFlag = 0;         /* True to delete file before opening */
-    /* Close the existing database */
+    int openMode = SHELL_OPEN_UNSPEC;
-    session_close_all(p, -1);
+
-    close_db(p->db);
-    p->db = 0;
-    p->pAuxDb->zDbFilename = 0;
-    sqlite3_free(p->pAuxDb->zFreeOnClose);
-    p->pAuxDb->zFreeOnClose = 0;
-    p->openMode = SHELL_OPEN_UNSPEC;
-    p->openFlags = 0;
-    p->szMax = 0;
     /* Check for command-line arguments */
     for(iName=1; iName<nArg; iName++){
       const char *z = azArg[iName];
@@ -8958,19 +8950,19 @@ static int do_meta_command(char *zLine, ShellState *p){
         newFlag = 1;
 #ifdef SQLITE_HAVE_ZLIB
       }else if( optionMatch(z, "zip") ){
-        p->openMode = SHELL_OPEN_ZIPFILE;
+        openMode = SHELL_OPEN_ZIPFILE;
 #endif
       }else if( optionMatch(z, "append") ){
-        p->openMode = SHELL_OPEN_APPENDVFS;
+        openMode = SHELL_OPEN_APPENDVFS;
       }else if( optionMatch(z, "readonly") ){
-        p->openMode = SHELL_OPEN_READONLY;
+        openMode = SHELL_OPEN_READONLY;
       }else if( optionMatch(z, "nofollow") ){
         p->openFlags |= SQLITE_OPEN_NOFOLLOW;
 #ifndef SQLITE_OMIT_DESERIALIZE
       }else if( optionMatch(z, "deserialize") ){
-        p->openMode = SHELL_OPEN_DESERIALIZE;
+        openMode = SHELL_OPEN_DESERIALIZE;
       }else if( optionMatch(z, "hexdb") ){
-        p->openMode = SHELL_OPEN_HEXDB;
+        openMode = SHELL_OPEN_HEXDB;
       }else if( optionMatch(z, "maxsize") && iName+1<nArg ){
         p->szMax = integerValue(azArg[++iName]);
 #endif /* SQLITE_OMIT_DESERIALIZE */
@@ -8986,6 +8978,18 @@ static int do_meta_command(char *zLine, ShellState *p){
         zNewFilename = sqlite3_mprintf("%s", z);
       }
     }
+
+    /* Close the existing database */
+    session_close_all(p, -1);
+    close_db(p->db);
+    p->db = 0;
+    p->pAuxDb->zDbFilename = 0;
+    sqlite3_free(p->pAuxDb->zFreeOnClose);
+    p->pAuxDb->zFreeOnClose = 0;
+    p->openMode = openMode;
+    p->openFlags = 0;
+    p->szMax = 0;
+
     /* If a filename is specified, try to open it first */
     if( zNewFilename || p->openMode==SHELL_OPEN_HEXDB ){
       if( newFlag && !p->bSafeMode ) shellDeleteFile(zNewFilename);

src/where.c

@@ -234,7 +234,12 @@ whereOrInsert_done:
 Bitmask sqlite3WhereGetMask(WhereMaskSet *pMaskSet, int iCursor){
   int i;
   assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 );
-  for(i=0; i<pMaskSet->n; i++){
+  assert( pMaskSet->n>0 || pMaskSet->ix[0]<0 );
+  assert( iCursor>=-1 );
+  if( pMaskSet->ix[0]==iCursor ){
+    return 1;
+  }
+  for(i=1; i<pMaskSet->n; i++){
     if( pMaskSet->ix[i]==iCursor ){
       return MASKBIT(i);
     }
@@ -419,16 +424,16 @@ static WhereTerm *whereScanInit(
   if( pIdx ){
     int j = iColumn;
     iColumn = pIdx->aiColumn[j];
-    if( iColumn==XN_EXPR ){
+    if( iColumn==pIdx->pTable->iPKey ){
-      pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
-      pScan->zCollName = pIdx->azColl[j];
-      pScan->aiColumn[0] = XN_EXPR;
-      return whereScanInitIndexExpr(pScan);
-    }else if( iColumn==pIdx->pTable->iPKey ){
       iColumn = XN_ROWID;
     }else if( iColumn>=0 ){
       pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
       pScan->zCollName = pIdx->azColl[j];
+    }else if( iColumn==XN_EXPR ){
+      pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
+      pScan->zCollName = pIdx->azColl[j];
+      pScan->aiColumn[0] = XN_EXPR;
+      return whereScanInitIndexExpr(pScan);
     }
   }else if( iColumn==XN_EXPR ){
     return 0;
@@ -4876,12 +4881,6 @@ WhereInfo *sqlite3WhereBegin(
   if( pOrderBy && pOrderBy->nExpr>=BMS ) pOrderBy = 0;
   sWLB.pOrderBy = pOrderBy;
 
-  /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
-  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
-  if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){
-    wctrlFlags &= ~WHERE_WANT_DISTINCT;
-  }
-
   /* The number of tables in the FROM clause is limited by the number of
   ** bits in a Bitmask 
   */
@@ -4928,6 +4927,10 @@ WhereInfo *sqlite3WhereBegin(
   memset(&pWInfo->a[0], 0, sizeof(WhereLoop)+nTabList*sizeof(WhereLevel));
   assert( pWInfo->eOnePass==ONEPASS_OFF );  /* ONEPASS defaults to OFF */
   pMaskSet = &pWInfo->sMaskSet;
+  pMaskSet->n = 0;
+  pMaskSet->ix[0] = -99; /* Initialize ix[0] to a value that can never be
+                         ** a valid cursor number, to avoid an initial
+                         ** test for pMaskSet->n==0 in sqlite3WhereGetMask() */
   sWLB.pWInfo = pWInfo;
   sWLB.pWC = &pWInfo->sWC;
   sWLB.pNew = (WhereLoop*)(((char*)pWInfo)+nByteWInfo);
@@ -4940,7 +4943,6 @@ WhereInfo *sqlite3WhereBegin(
   /* Split the WHERE clause into separate subexpressions where each
   ** subexpression is separated by an AND operator.
   */
-  initMaskSet(pMaskSet);
   sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo);
   sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND);
     
@@ -4948,7 +4950,9 @@ WhereInfo *sqlite3WhereBegin(
   */
   if( nTabList==0 ){
     if( pOrderBy ) pWInfo->nOBSat = pOrderBy->nExpr;
-    if( wctrlFlags & WHERE_WANT_DISTINCT ){
+    if( (wctrlFlags & WHERE_WANT_DISTINCT)!=0
+     && OptimizationEnabled(db, SQLITE_DistinctOpt)
+    ){
       pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
     }
     ExplainQueryPlan((pParse, 0, "SCAN CONSTANT ROW"));
@@ -5009,7 +5013,12 @@ WhereInfo *sqlite3WhereBegin(
   }
 
   if( wctrlFlags & WHERE_WANT_DISTINCT ){
-    if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
+    if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){
+      /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
+      ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
+      wctrlFlags &= ~WHERE_WANT_DISTINCT;
+      pWInfo->wctrlFlags &= ~WHERE_WANT_DISTINCT;
+    }else if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
       /* The DISTINCT marking is pointless.  Ignore it. */
       pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
     }else if( pOrderBy==0 ){

src/whereInt.h

@@ -293,11 +293,11 @@ struct WhereScan {
   WhereClause *pWC;          /* WhereClause currently being scanned */
   const char *zCollName;     /* Required collating sequence, if not NULL */
   Expr *pIdxExpr;            /* Search for this index expression */
-  char idxaff;               /* Must match this affinity, if zCollName!=NULL */
-  unsigned char nEquiv;      /* Number of entries in aiCur[] and aiColumn[] */
-  unsigned char iEquiv;      /* Next unused slot in aiCur[] and aiColumn[] */
-  u32 opMask;                /* Acceptable operators */
   int k;                     /* Resume scanning at this->pWC->a[this->k] */
+  u32 opMask;                /* Acceptable operators */
+  char idxaff;               /* Must match this affinity, if zCollName!=NULL */
+  unsigned char iEquiv;      /* Current slot in aiCur[] and aiColumn[] */
+  unsigned char nEquiv;      /* Number of entries in aiCur[] and aiColumn[] */
   int aiCur[11];             /* Cursors in the equivalence class */
   i16 aiColumn[11];          /* Corresponding column number in the eq-class */
 };
@@ -378,11 +378,6 @@ struct WhereMaskSet {
   int ix[BMS];                  /* Cursor assigned to each bit */
 };
 
-/*
-** Initialize a WhereMaskSet object
-*/
-#define initMaskSet(P)  (P)->n=0
-
 /*
 ** This object is a convenience wrapper holding all information needed
 ** to construct WhereLoop objects for a particular query.

src/whereexpr.c

@@ -1070,10 +1070,13 @@ static void exprAnalyze(
   if( db->mallocFailed ){
     return;
   }
+  assert( pWC->nTerm > idxTerm );
   pTerm = &pWC->a[idxTerm];
   pMaskSet = &pWInfo->sMaskSet;
   pExpr = pTerm->pExpr;
+  assert( pExpr!=0 ); /* Because malloc() has not failed */
   assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
+  pMaskSet->bVarSelect = 0;
   prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
   op = pExpr->op;
   if( op==TK_IN ){
@@ -1084,14 +1087,28 @@ static void exprAnalyze(
     }else{
       pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
     }
-  }else if( op==TK_ISNULL ){
+    prereqAll = prereqLeft | pTerm->prereqRight;
-    pTerm->prereqRight = 0;
   }else{
     pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
+    if( pExpr->pLeft==0
+     || ExprHasProperty(pExpr, EP_xIsSelect|EP_IfNullRow)
+     || pExpr->x.pList!=0
+    ){
+      prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
+    }else{
+      prereqAll = prereqLeft | pTerm->prereqRight;
+    }
   }
-  pMaskSet->bVarSelect = 0;
-  prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
   if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
+
+#ifdef SQLITE_DEBUG
+  if( prereqAll!=sqlite3WhereExprUsageNN(pMaskSet, pExpr) ){
+    printf("\n*** Incorrect prereqAll computed for:\n");
+    sqlite3TreeViewExpr(0,pExpr,0);
+    abort();
+  }
+#endif
+
   if( ExprHasProperty(pExpr, EP_FromJoin) ){
     Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
     prereqAll |= x;
@@ -1525,17 +1542,25 @@ void sqlite3WhereClauseInit(
 ** sqlite3WhereClauseInit().
 */
 void sqlite3WhereClauseClear(WhereClause *pWC){
-  int i;
-  WhereTerm *a;
   sqlite3 *db = pWC->pWInfo->pParse->db;
-  for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
+  if( pWC->nTerm>0 ){
-    if( a->wtFlags & TERM_DYNAMIC ){
+    WhereTerm *a = pWC->a;
-      sqlite3ExprDelete(db, a->pExpr);
+    WhereTerm *aLast = &pWC->a[pWC->nTerm-1];
-    }
+    while(1){
-    if( a->wtFlags & TERM_ORINFO ){
+      if( a->wtFlags & TERM_DYNAMIC ){
-      whereOrInfoDelete(db, a->u.pOrInfo);
+        sqlite3ExprDelete(db, a->pExpr);
-    }else if( a->wtFlags & TERM_ANDINFO ){
+      }
-      whereAndInfoDelete(db, a->u.pAndInfo);
+      if( a->wtFlags & (TERM_ORINFO|TERM_ANDINFO) ){
+        if( a->wtFlags & TERM_ORINFO ){
+          assert( (a->wtFlags & TERM_ANDINFO)==0 );
+          whereOrInfoDelete(db, a->u.pOrInfo);
+        }else{
+          assert( (a->wtFlags & TERM_ANDINFO)!=0 );
+          whereAndInfoDelete(db, a->u.pAndInfo);
+        }
+      }
+      if( a==aLast ) break;
+      a++;
     }
   }
   if( pWC->a!=pWC->aStatic ){
@@ -1548,15 +1573,38 @@ void sqlite3WhereClauseClear(WhereClause *pWC){
 ** These routines walk (recursively) an expression tree and generate
 ** a bitmask indicating which tables are used in that expression
 ** tree.
+**
+** sqlite3WhereExprUsage(MaskSet, Expr) ->
+**
+**       Return a Bitmask of all tables referenced by Expr.  Expr can be
+**       be NULL, in which case 0 is returned.
+**
+** sqlite3WhereExprUsageNN(MaskSet, Expr) ->
+**
+**       Same as sqlite3WhereExprUsage() except that Expr must not be
+**       NULL.  The "NN" suffix on the name stands for "Not Null".
+**
+** sqlite3WhereExprListUsage(MaskSet, ExprList) ->
+**
+**       Return a Bitmask of all tables referenced by every expression
+**       in the expression list ExprList.  ExprList can be NULL, in which
+**       case 0 is returned.
+**
+** sqlite3WhereExprUsageFull(MaskSet, ExprList) ->
+**
+**       Internal use only.  Called only by sqlite3WhereExprUsageNN() for
+**       complex expressions that require pushing register values onto
+**       the stack.  Many calls to sqlite3WhereExprUsageNN() do not need
+**       the more complex analysis done by this routine.  Hence, the
+**       computations done by this routine are broken out into a separate
+**       "no-inline" function to avoid the stack push overhead in the
+**       common case where it is not needed.
 */
-Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
+static SQLITE_NOINLINE Bitmask sqlite3WhereExprUsageFull(
+  WhereMaskSet *pMaskSet,
+  Expr *p
+){
   Bitmask mask;
-  if( p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){
-    return sqlite3WhereGetMask(pMaskSet, p->iTable);
-  }else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
-    assert( p->op!=TK_IF_NULL_ROW );
-    return 0;
-  }
   mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;
   if( p->pLeft ) mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pLeft);
   if( p->pRight ){
@@ -1578,6 +1626,15 @@ Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
 #endif
   return mask;
 }
+Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
+  if( p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){
+    return sqlite3WhereGetMask(pMaskSet, p->iTable);
+  }else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
+    assert( p->op!=TK_IF_NULL_ROW );
+    return 0;
+  }
+  return sqlite3WhereExprUsageFull(pMaskSet, p);
+}
 Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
   return p ? sqlite3WhereExprUsageNN(pMaskSet,p) : 0;
 }