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Proposed optimization to the IS NULL and NOT NULL operators that avoids

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loading the entire content of larges strings and BLOBs.  Response to
[forum:/info/3c08d4715dc05b00|forum post 3c08d4715dc05b00].

FossilOrigin-Name: 45f171565442f9fd6574fb93ae7abe83c168b20be68af42531bc55571450d3ab
This commit is contained in:
drh
2022-10-13 12:47:33 +00:00
parent 1ffb6be119
commit e995d2c226
6 changed files with 33 additions and 13 deletions
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2
src/expr.c
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@@ -5241,6 +5241,7 @@ void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
assert( TK_ISNULL==OP_IsNull ); testcase( op==TK_ISNULL );
assert( TK_NOTNULL==OP_NotNull ); testcase( op==TK_NOTNULL );
r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
sqlite3VdbeTypeofColumn(v, r1);
sqlite3VdbeAddOp2(v, op, r1, dest);
VdbeCoverageIf(v, op==TK_ISNULL);
VdbeCoverageIf(v, op==TK_NOTNULL);
@@ -5415,6 +5416,7 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
case TK_ISNULL:
case TK_NOTNULL: {
r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
sqlite3VdbeTypeofColumn(v, r1);
sqlite3VdbeAddOp2(v, op, r1, dest);
testcase( op==TK_ISNULL ); VdbeCoverageIf(v, op==TK_ISNULL);
testcase( op==TK_NOTNULL ); VdbeCoverageIf(v, op==TK_NOTNULL);

4
src/pragma.c
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@@ -1791,9 +1791,7 @@ void sqlite3Pragma(
|| pTab->iPKey==mxCol) ) mxCol--;
if( mxCol>=0 ){
sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, mxCol, 3);
if( sqlite3VdbeGetLastOp(v)->opcode==OP_Column ){
sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
}
sqlite3VdbeTypeofColumn(v, 3);
}
if( !isQuick ){

1
src/vdbe.h
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@@ -228,6 +228,7 @@ void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
void sqlite3VdbeTypeofColumn(Vdbe*, int);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
void sqlite3VdbeJumpHereOrPopInst(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);

16
src/vdbeaux.c
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@@ -1155,6 +1155,22 @@ void sqlite3VdbeChangeP5(Vdbe *p, u16 p5){
if( p->nOp>0 ) p->aOp[p->nOp-1].p5 = p5;
}
/*
** If the previous opcode is an OP_Column that delivers results
** into register iDest, then add the OPFLAG_TYPEOF flag to that
** opcode.
*/
void sqlite3VdbeTypeofColumn(Vdbe *p, int iDest){
if( p->nOp>0 ){
VdbeOp *pOp = &p->aOp[p->nOp-1];
if( pOp->opcode==OP_Column && pOp->p3==iDest ){
pOp->p5 |= OPFLAG_TYPEOFARG;
}
}else{
assert( p->db->mallocFailed );
}
}
/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.