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Enhance the query planner so that it is able to use indexed expressions

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to help fulfill an ORDER BY clause.

FossilOrigin-Name: 668fc1ebaf426f9eed3ed7865e41f1023dafebfb
This commit is contained in:
drh
2015-09-24 18:47:59 +00:00
parent 76226dd28d
commit dae26fe518
4 changed files with 63 additions and 13 deletions
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23
src/where.c
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@@ -2421,18 +2421,25 @@ static int indexMightHelpWithOrderBy(
int iCursor
){
ExprList *pOB;
ExprList *aColExpr;
int ii, jj;
if( pIndex->bUnordered ) return 0;
if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
for(ii=0; ii<pOB->nExpr; ii++){
Expr *pExpr = sqlite3ExprSkipCollate(pOB->a[ii].pExpr);
if( pExpr->op!=TK_COLUMN ) return 0;
if( pExpr->iTable==iCursor ){
if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){
if( pExpr->iColumn<0 ) return 1;
for(jj=0; jj<pIndex->nKeyCol; jj++){
if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1;
}
}else if( (aColExpr = pIndex->aColExpr)!=0 ){
for(jj=0; jj<pIndex->nKeyCol; jj++){
if( pIndex->aiColumn[jj]!=(-2) ) continue;
if( sqlite3ExprCompare(pExpr,aColExpr->a[jj].pExpr,iCursor)==0 ){
return 1;
}
}
}
}
return 0;
@@ -3264,9 +3271,15 @@ static i8 wherePathSatisfiesOrderBy(
testcase( wctrlFlags & WHERE_GROUPBY );
testcase( wctrlFlags & WHERE_DISTINCTBY );
if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0;
if( pOBExpr->op!=TK_COLUMN ) continue;
if( pOBExpr->iTable!=iCur ) continue;
if( pOBExpr->iColumn!=iColumn ) continue;
if( iColumn>=(-1) ){
if( pOBExpr->op!=TK_COLUMN ) continue;
if( pOBExpr->iTable!=iCur ) continue;
if( pOBExpr->iColumn!=iColumn ) continue;
}else{
if( sqlite3ExprCompare(pOBExpr,pIndex->aColExpr->a[j].pExpr,iCur) ){
continue;
}
}
if( iColumn>=0 ){
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
if( !pColl ) pColl = db->pDfltColl;