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Use the estimated number of rows computed for subqueries in the cost

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computations for outer queries.

FossilOrigin-Name: 56bbc539246a6dc9f1ae1edb898db7a4f6f6d322
This commit is contained in:
drh
2010-11-16 02:49:15 +00:00
parent 04098e6085
commit 95aa47b10a
7 changed files with 82 additions and 19 deletions
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20
src/select.c
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@@ -1433,6 +1433,8 @@ static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
VdbeComment((v, "LIMIT counter"));
if( n==0 ){
sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
}else{
if( p->nSelectRow > (double)n ) p->nSelectRow = (double)n;
}
}else{
sqlite3ExprCode(pParse, p->pLimit, iLimit);
@@ -1594,6 +1596,7 @@ static int multiSelect(
switch( p->op ){
case TK_ALL: {
int addr = 0;
int nLimit;
assert( !pPrior->pLimit );
pPrior->pLimit = p->pLimit;
pPrior->pOffset = p->pOffset;
@@ -1616,6 +1619,13 @@ static int multiSelect(
testcase( rc!=SQLITE_OK );
pDelete = p->pPrior;
p->pPrior = pPrior;
p->nSelectRow += pPrior->nSelectRow;
if( pPrior->pLimit
&& sqlite3ExprIsInteger(pPrior->pLimit, &nLimit)
&& p->nSelectRow > (double)nLimit
){
p->nSelectRow = (double)nLimit;
}
if( addr ){
sqlite3VdbeJumpHere(v, addr);
}
@@ -1688,6 +1698,7 @@ static int multiSelect(
pDelete = p->pPrior;
p->pPrior = pPrior;
p->pOrderBy = 0;
if( p->op==TK_UNION ) p->nSelectRow += pPrior->nSelectRow;
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
p->pOffset = pOffset;
@@ -1767,6 +1778,7 @@ static int multiSelect(
testcase( rc!=SQLITE_OK );
pDelete = p->pPrior;
p->pPrior = pPrior;
if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
p->pOffset = pOffset;
@@ -2353,6 +2365,7 @@ static int multiSelectOrderBy(
sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA);
p->nSelectRow += pPrior->nSelectRow;
}
/* Generate a subroutine to run when the results from select B
@@ -2360,6 +2373,7 @@ static int multiSelectOrderBy(
*/
if( op==TK_INTERSECT ){
addrEofB = addrEofA;
if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
}else{
VdbeNoopComment((v, "eof-B subroutine"));
addrEofB = sqlite3VdbeAddOp2(v, OP_If, regEofA, labelEnd);
@@ -3754,6 +3768,7 @@ int sqlite3Select(
explainSetInteger(pItem->iSelectId, pParse->iNextSelectId);
sqlite3Select(pParse, pSub, &dest);
pItem->isPopulated = 1;
pItem->pTab->nRowEst = (unsigned)pSub->nSelectRow;
}
if( /*pParse->nErr ||*/ db->mallocFailed ){
goto select_end;
@@ -3846,6 +3861,7 @@ int sqlite3Select(
/* Set the limiter.
*/
iEnd = sqlite3VdbeMakeLabel(v);
p->nSelectRow = (double)LARGEST_INT64;
computeLimitRegisters(pParse, p, iEnd);
/* Open a virtual index to use for the distinct set.
@@ -3869,6 +3885,7 @@ int sqlite3Select(
*/
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, 0);
if( pWInfo==0 ) goto select_end;
if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut;
/* If sorting index that was created by a prior OP_OpenEphemeral
** instruction ended up not being needed, then change the OP_OpenEphemeral
@@ -3913,6 +3930,9 @@ int sqlite3Select(
for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){
pItem->iAlias = 0;
}
if( p->nSelectRow>(double)100 ) p->nSelectRow = (double)100;
}else{
p->nSelectRow = (double)1;
}