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A new implementation of indexing with the IS operator that works correctly

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when the IS operator is in the WHERE clause and the operands are from 
opposite sides of a LEFT JOIN.

FossilOrigin-Name: 4541688b3f56f5cd3d5b299594b58c577ad633bb
This commit is contained in:
drh
2015-05-14 01:05:25 +00:00
parent 9be1870994
commit e8d0c61f0a
5 changed files with 63 additions and 40 deletions
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16
manifest
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@@ -1,5 +1,5 @@
C Simplified\simplementation\sof\sindexing\swith\sthe\sIS\soperator. C A\snew\simplementation\sof\sindexing\swith\sthe\sIS\soperator\sthat\sworks\scorrectly\nwhen\sthe\sIS\soperator\sis\sin\sthe\sWHERE\sclause\sand\sthe\soperands\sare\sfrom\s\nopposite\ssides\sof\sa\sLEFT\sJOIN.
D 2015-05-13T19:33:41.990 D 2015-05-14T01:05:25.274
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in edfc69769e613a6359c42c06ea1d42c3bece1736 F Makefile.in edfc69769e613a6359c42c06ea1d42c3bece1736
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -307,8 +307,8 @@ F src/vxworks.h c18586c8edc1bddbc15c004fa16aeb1e1342b4fb
F src/wal.c ce2cb2d06faab54d1bce3e739bec79e063dd9113 F src/wal.c ce2cb2d06faab54d1bce3e739bec79e063dd9113
F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
F src/walker.c c253b95b4ee44b21c406e2a1052636c31ea27804 F src/walker.c c253b95b4ee44b21c406e2a1052636c31ea27804
F src/where.c fa61aca146422a2a056aeb0381a6bb1c37d46c07 F src/where.c 64afb483fe8bede1e31e6c66bc532530a4600543
F src/whereInt.h 31d30e83621c21358d031510d5c6a3e474cd8bb7 F src/whereInt.h a6f5a762bc1b4b1c76e1cea79976b437ac35a435
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
F test/aggnested.test b35b4cd69fc913f90d39a575e171e1116c3a4bb7 F test/aggnested.test b35b4cd69fc913f90d39a575e171e1116c3a4bb7
@@ -1168,7 +1168,7 @@ F test/walthread.test de8dbaf6d9e41481c460ba31ca61e163d7348f8e
F test/where.test 1ff3d9f8da0a6c0dc5ccfd38d9225b2cdb5b6afb F test/where.test 1ff3d9f8da0a6c0dc5ccfd38d9225b2cdb5b6afb
F test/where2.test 23fdb5d8e756554aad4ca7ae03de9dd8367a2c6e F test/where2.test 23fdb5d8e756554aad4ca7ae03de9dd8367a2c6e
F test/where3.test 1ad55ba900bd7747f98b6082e65bd3e442c5004e F test/where3.test 1ad55ba900bd7747f98b6082e65bd3e442c5004e
F test/where4.test d8420ceeb8323a41ceff1f1841fc528e824e1ecf F test/where4.test a4603fa0d018bd4b9430dac840c9c522af421dd5
F test/where5.test fdf66f96d29a064b63eb543e28da4dfdccd81ad2 F test/where5.test fdf66f96d29a064b63eb543e28da4dfdccd81ad2
F test/where6.test 5da5a98cec820d488e82708301b96cb8c18a258b F test/where6.test 5da5a98cec820d488e82708301b96cb8c18a258b
F test/where7.test 5a4b0abc207d71da4deecd734ad8579e8dd40aa8 F test/where7.test 5a4b0abc207d71da4deecd734ad8579e8dd40aa8
@@ -1258,7 +1258,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P 24263d08b11c88416d270013bdaf5ff45125cb4d P 95b1f9bf14e490c6c6bba9ea78aeab712a44aab5
R 16be24e7bac77474bad7ab9d3d121f18 R 6e0cd1da1bcd5d739d5d402ab5201f6c
U drh U drh
Z 3bc6b705447a86373e017a72613abb32 Z 3608a708c2f560b3e002545b6da23dda

2
manifest.uuid
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@@ -1 +1 @@
95b1f9bf14e490c6c6bba9ea78aeab712a44aab5 4541688b3f56f5cd3d5b299594b58c577ad633bb

49
src/where.c
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@@ -417,7 +417,7 @@ static u16 operatorMask(int op){
}else if( op==TK_ISNULL ){ }else if( op==TK_ISNULL ){
c = WO_ISNULL; c = WO_ISNULL;
}else if( op==TK_IS ){ }else if( op==TK_IS ){
c = WO_EQ; /* IS works like ==, just without the IsNull tests */ c = WO_IS;
}else{ }else{
assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff ); assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
c = (u16)(WO_EQ<<(op-TK_EQ)); c = (u16)(WO_EQ<<(op-TK_EQ));
@@ -429,7 +429,7 @@ static u16 operatorMask(int op){
assert( op!=TK_LE || c==WO_LE ); assert( op!=TK_LE || c==WO_LE );
assert( op!=TK_GT || c==WO_GT ); assert( op!=TK_GT || c==WO_GT );
assert( op!=TK_GE || c==WO_GE ); assert( op!=TK_GE || c==WO_GE );
assert( op!=TK_IS || c==WO_EQ ); assert( op!=TK_IS || c==WO_IS );
return c; return c;
} }
@@ -490,11 +490,12 @@ static WhereTerm *whereScanNext(WhereScan *pScan){
continue; continue;
} }
} }
if( (pTerm->eOperator & WO_EQ)!=0 if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
&& (pX = pTerm->pExpr->pRight)->op==TK_COLUMN && (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
&& pX->iTable==pScan->aEquiv[0] && pX->iTable==pScan->aEquiv[0]
&& pX->iColumn==pScan->aEquiv[1] && pX->iColumn==pScan->aEquiv[1]
){ ){
testcase( pTerm->eOperator & WO_IS );
continue; continue;
} }
pScan->k = k+1; pScan->k = k+1;
@@ -596,9 +597,11 @@ static WhereTerm *findTerm(
WhereScan scan; WhereScan scan;
p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx); p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
op &= WO_EQ|WO_IS;
while( p ){ while( p ){
if( (p->prereqRight & notReady)==0 ){ if( (p->prereqRight & notReady)==0 ){
if( p->prereqRight==0 && (p->eOperator&WO_EQ)!=0 ){ if( p->prereqRight==0 && (p->eOperator&op)!=0 ){
testcase( p->eOperator & WO_IS );
return p; return p;
} }
if( pResult==0 ) pResult = p; if( pResult==0 ) pResult = p;
@@ -1679,7 +1682,7 @@ static int termCanDriveIndex(
){ ){
char aff; char aff;
if( pTerm->leftCursor!=pSrc->iCursor ) return 0; if( pTerm->leftCursor!=pSrc->iCursor ) return 0;
if( (pTerm->eOperator & WO_EQ)==0 ) return 0; if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) return 0;
if( (pTerm->prereqRight & notReady)!=0 ) return 0; if( (pTerm->prereqRight & notReady)!=0 ) return 0;
if( pTerm->u.leftColumn<0 ) return 0; if( pTerm->u.leftColumn<0 ) return 0;
aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity; aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity;
@@ -1955,7 +1958,7 @@ static sqlite3_index_info *allocateIndexInfo(
testcase( pTerm->eOperator & WO_IN ); testcase( pTerm->eOperator & WO_IN );
testcase( pTerm->eOperator & WO_ISNULL ); testcase( pTerm->eOperator & WO_ISNULL );
testcase( pTerm->eOperator & WO_ALL ); testcase( pTerm->eOperator & WO_ALL );
if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV))==0 ) continue; if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
if( pTerm->wtFlags & TERM_VNULL ) continue; if( pTerm->wtFlags & TERM_VNULL ) continue;
pIdxCons[j].iColumn = pTerm->u.leftColumn; pIdxCons[j].iColumn = pTerm->u.leftColumn;
pIdxCons[j].iTermOffset = i; pIdxCons[j].iTermOffset = i;
@@ -4104,16 +4107,18 @@ static Bitmask codeOneLoopStart(
Expr *pE, *pEAlt; Expr *pE, *pEAlt;
WhereTerm *pAlt; WhereTerm *pAlt;
if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
if( pTerm->eOperator!=(WO_EQUIV|WO_EQ) ) continue; if( (pTerm->eOperator&(WO_EQUIV|WO_EQ|WO_IS))<=WO_EQUIV ) continue;
if( pTerm->leftCursor!=iCur ) continue; if( pTerm->leftCursor!=iCur ) continue;
if( pLevel->iLeftJoin ) continue; if( pLevel->iLeftJoin ) continue;
pE = pTerm->pExpr; pE = pTerm->pExpr;
assert( !ExprHasProperty(pE, EP_FromJoin) ); assert( !ExprHasProperty(pE, EP_FromJoin) );
assert( (pTerm->prereqRight & pLevel->notReady)!=0 ); assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
pAlt = findTerm(pWC, iCur, pTerm->u.leftColumn, notReady, WO_EQ|WO_IN, 0); pAlt = findTerm(pWC, iCur, pTerm->u.leftColumn, notReady,
WO_EQ|WO_IN|WO_IS, 0);
if( pAlt==0 ) continue; if( pAlt==0 ) continue;
if( pAlt->wtFlags & (TERM_CODED) ) continue; if( pAlt->wtFlags & (TERM_CODED) ) continue;
testcase( (pAlt->eOperator & WO_EQ)!=0 && pAlt->pExpr->op==TK_IS ); testcase( pAlt->eOperator & WO_EQ );
testcase( pAlt->eOperator & WO_IS );
testcase( pAlt->eOperator & WO_IN ); testcase( pAlt->eOperator & WO_IN );
VdbeModuleComment((v, "begin transitive constraint")); VdbeModuleComment((v, "begin transitive constraint"));
pEAlt = sqlite3StackAllocRaw(db, sizeof(*pEAlt)); pEAlt = sqlite3StackAllocRaw(db, sizeof(*pEAlt));
@@ -4656,7 +4661,7 @@ static void whereLoopOutputAdjust(
/* In the absence of explicit truth probabilities, use heuristics to /* In the absence of explicit truth probabilities, use heuristics to
** guess a reasonable truth probability. */ ** guess a reasonable truth probability. */
pLoop->nOut--; pLoop->nOut--;
if( pTerm->eOperator&WO_EQ ){ if( pTerm->eOperator&(WO_EQ|WO_IS) ){
Expr *pRight = pTerm->pExpr->pRight; Expr *pRight = pTerm->pExpr->pRight;
testcase( pTerm->pExpr->op==TK_IS ); testcase( pTerm->pExpr->op==TK_IS );
if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){ if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){
@@ -4729,7 +4734,7 @@ static int whereLoopAddBtreeIndex(
}else if( pProbe->tnum<=0 || (pSrc->jointype & JT_LEFT)!=0 ){ }else if( pProbe->tnum<=0 || (pSrc->jointype & JT_LEFT)!=0 ){
opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE; opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE;
}else{ }else{
opMask = WO_EQ|WO_IN|WO_ISNULL|WO_GT|WO_GE|WO_LT|WO_LE; opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE|WO_ISNULL|WO_IS;
} }
if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE); if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE);
@@ -4792,7 +4797,7 @@ static int whereLoopAddBtreeIndex(
assert( nIn>0 ); /* RHS always has 2 or more terms... The parser assert( nIn>0 ); /* RHS always has 2 or more terms... The parser
** changes "x IN (?)" into "x=?". */ ** changes "x IN (?)" into "x=?". */
}else if( eOp & (WO_EQ) ){ }else if( eOp & (WO_EQ|WO_IS) ){
pNew->wsFlags |= WHERE_COLUMN_EQ; pNew->wsFlags |= WHERE_COLUMN_EQ;
if( iCol<0 || (nInMul==0 && pNew->u.btree.nEq==pProbe->nKeyCol-1) ){ if( iCol<0 || (nInMul==0 && pNew->u.btree.nEq==pProbe->nKeyCol-1) ){
if( iCol>=0 && pProbe->uniqNotNull==0 ){ if( iCol>=0 && pProbe->uniqNotNull==0 ){
@@ -4842,7 +4847,7 @@ static int whereLoopAddBtreeIndex(
whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew); whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew);
}else{ }else{
int nEq = ++pNew->u.btree.nEq; int nEq = ++pNew->u.btree.nEq;
assert( eOp & (WO_ISNULL|WO_EQ|WO_IN) ); assert( eOp & (WO_ISNULL|WO_EQ|WO_IN|WO_IS) );
assert( pNew->nOut==saved_nOut ); assert( pNew->nOut==saved_nOut );
if( pTerm->truthProb<=0 && iCol>=0 ){ if( pTerm->truthProb<=0 && iCol>=0 ){
@@ -4859,8 +4864,9 @@ static int whereLoopAddBtreeIndex(
&& ((eOp & WO_IN)==0 || !ExprHasProperty(pTerm->pExpr, EP_xIsSelect)) && ((eOp & WO_IN)==0 || !ExprHasProperty(pTerm->pExpr, EP_xIsSelect))
){ ){
Expr *pExpr = pTerm->pExpr; Expr *pExpr = pTerm->pExpr;
if( (eOp & (WO_EQ|WO_ISNULL))!=0 ){ if( (eOp & (WO_EQ|WO_ISNULL|WO_IS))!=0 ){
testcase( (eOp & WO_EQ)!=0 && pExpr->op==TK_IS ); testcase( eOp & WO_EQ );
testcase( eOp & WO_IS );
testcase( eOp & WO_ISNULL ); testcase( eOp & WO_ISNULL );
rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut); rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut);
}else{ }else{
@@ -5697,9 +5703,9 @@ static i8 wherePathSatisfiesOrderBy(
if( pOBExpr->op!=TK_COLUMN ) continue; if( pOBExpr->op!=TK_COLUMN ) continue;
if( pOBExpr->iTable!=iCur ) continue; if( pOBExpr->iTable!=iCur ) continue;
pTerm = findTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn, pTerm = findTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
~ready, WO_EQ|WO_ISNULL, 0); ~ready, WO_EQ|WO_ISNULL|WO_IS, 0);
if( pTerm==0 ) continue; if( pTerm==0 ) continue;
if( (pTerm->eOperator&WO_EQ)!=0 && pOBExpr->iColumn>=0 ){ if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
const char *z1, *z2; const char *z1, *z2;
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr); pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
if( !pColl ) pColl = db->pDfltColl; if( !pColl ) pColl = db->pDfltColl;
@@ -5739,7 +5745,7 @@ static i8 wherePathSatisfiesOrderBy(
/* Skip over == and IS NULL terms */ /* Skip over == and IS NULL terms */
if( j<pLoop->u.btree.nEq if( j<pLoop->u.btree.nEq
&& pLoop->nSkip==0 && pLoop->nSkip==0
&& ((i = pLoop->aLTerm[j]->eOperator) & (WO_EQ|WO_ISNULL))!=0 && ((i = pLoop->aLTerm[j]->eOperator) & (WO_EQ|WO_ISNULL|WO_IS))!=0
){ ){
if( i & WO_ISNULL ){ if( i & WO_ISNULL ){
testcase( isOrderDistinct ); testcase( isOrderDistinct );
@@ -6312,8 +6318,9 @@ static int whereShortCut(WhereLoopBuilder *pBuilder){
pLoop = pBuilder->pNew; pLoop = pBuilder->pNew;
pLoop->wsFlags = 0; pLoop->wsFlags = 0;
pLoop->nSkip = 0; pLoop->nSkip = 0;
pTerm = findTerm(pWC, iCur, -1, 0, WO_EQ, 0); pTerm = findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IS, 0);
if( pTerm ){ if( pTerm ){
testcase( pTerm->eOperator & WO_IS );
pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW; pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW;
pLoop->aLTerm[0] = pTerm; pLoop->aLTerm[0] = pTerm;
pLoop->nLTerm = 1; pLoop->nLTerm = 1;
@@ -6328,10 +6335,10 @@ static int whereShortCut(WhereLoopBuilder *pBuilder){
|| pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace)
) continue; ) continue;
for(j=0; j<pIdx->nKeyCol; j++){ for(j=0; j<pIdx->nKeyCol; j++){
pTerm = findTerm(pWC, iCur, pIdx->aiColumn[j], 0, WO_EQ, pIdx); pTerm = findTerm(pWC, iCur, pIdx->aiColumn[j], 0, WO_EQ|WO_IS, pIdx);
if( pTerm==0 ) break; if( pTerm==0 ) break;
testcase( pTerm->eOperator & WO_IS );
pLoop->aLTerm[j] = pTerm; pLoop->aLTerm[j] = pTerm;
testcase( pTerm->pExpr->op==TK_IS );
} }
if( j!=pIdx->nKeyCol ) continue; if( j!=pIdx->nKeyCol ) continue;
pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED; pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED;

21
src/whereInt.h
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@@ -429,21 +429,22 @@ struct WhereInfo {
** OR-ed combination of these values can be used when searching for ** OR-ed combination of these values can be used when searching for
** particular WhereTerms within a WhereClause. ** particular WhereTerms within a WhereClause.
*/ */
#define WO_IN 0x001 #define WO_IN 0x0001
#define WO_EQ 0x002 /* Used for both == and IS */ #define WO_EQ 0x0002
#define WO_LT (WO_EQ<<(TK_LT-TK_EQ)) #define WO_LT (WO_EQ<<(TK_LT-TK_EQ))
#define WO_LE (WO_EQ<<(TK_LE-TK_EQ)) #define WO_LE (WO_EQ<<(TK_LE-TK_EQ))
#define WO_GT (WO_EQ<<(TK_GT-TK_EQ)) #define WO_GT (WO_EQ<<(TK_GT-TK_EQ))
#define WO_GE (WO_EQ<<(TK_GE-TK_EQ)) #define WO_GE (WO_EQ<<(TK_GE-TK_EQ))
#define WO_MATCH 0x040 #define WO_MATCH 0x0040
#define WO_ISNULL 0x080 #define WO_IS 0x0080
#define WO_OR 0x100 /* Two or more OR-connected terms */ #define WO_ISNULL 0x0100
#define WO_AND 0x200 /* Two or more AND-connected terms */ #define WO_OR 0x0200 /* Two or more OR-connected terms */
#define WO_EQUIV 0x400 /* Of the form A==B, both columns */ #define WO_AND 0x0400 /* Two or more AND-connected terms */
#define WO_NOOP 0x800 /* This term does not restrict search space */ #define WO_EQUIV 0x0800 /* Of the form A==B, both columns */
#define WO_NOOP 0x1000 /* This term does not restrict search space */
#define WO_ALL 0xfff /* Mask of all possible WO_* values */ #define WO_ALL 0x1fff /* Mask of all possible WO_* values */
#define WO_SINGLE 0x0ff /* Mask of all non-compound WO_* values */ #define WO_SINGLE 0x01ff /* Mask of all non-compound WO_* values */
/* /*
** These are definitions of bits in the WhereLoop.wsFlags field. ** These are definitions of bits in the WhereLoop.wsFlags field.

15
test/where4.test
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@@ -57,6 +57,10 @@ proc count sql {
do_test where4-1.1 { do_test where4-1.1 {
count {SELECT rowid FROM t1 WHERE w IS NULL} count {SELECT rowid FROM t1 WHERE w IS NULL}
} {7 2} } {7 2}
do_test where4-1.1b {
unset -nocomplain null
count {SELECT rowid FROM t1 WHERE w IS $null}
} {7 2}
do_test where4-1.2 { do_test where4-1.2 {
count {SELECT rowid FROM t1 WHERE +w IS NULL} count {SELECT rowid FROM t1 WHERE +w IS NULL}
} {7 6} } {7 6}
@@ -143,6 +147,17 @@ do_test where4-3.2 {
SELECT * FROM t2 LEFT JOIN t3 ON a=x WHERE y IS NULL; SELECT * FROM t2 LEFT JOIN t3 ON a=x WHERE y IS NULL;
} }
} {2 2 {} 3 {} {}} } {2 2 {} 3 {} {}}
do_test where4-3.3 {
execsql {
SELECT * FROM t2 LEFT JOIN t3 ON a=x WHERE NULL is y;
}
} {2 2 {} 3 {} {}}
do_test where4-3.4 {
unset -nocomplain null
execsql {
SELECT * FROM t2 LEFT JOIN t3 ON a=x WHERE y IS $null;
}
} {2 2 {} 3 {} {}}
# Ticket #2189. Probably the same bug as #2177. # Ticket #2189. Probably the same bug as #2177.
# #