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Fix the skip-ahead-distinct optimization so that it works with indexes that

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have repeated columns with different collating sequences.

FossilOrigin-Name: ce1e2b88777e00a82c04abe5ba35eec81b5f324e462f099cd00b21054f369688
This commit is contained in:
drh
2017-04-13 21:29:02 +00:00
parent c04ea80f64
commit 172806e489
5 changed files with 58 additions and 48 deletions
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46
src/where.c
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@@ -3532,6 +3532,8 @@ static i8 wherePathSatisfiesOrderBy(
if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){
if( pLoop->u.vtab.isOrdered ) obSat = obDone;
break;
}else{
pLoop->u.btree.nIdxCol = 0;
}
iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
@@ -3677,6 +3679,7 @@ static i8 wherePathSatisfiesOrderBy(
if( !pColl ) pColl = db->pDfltColl;
if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue;
}
if( pLoop->u.btree.nIdxCol<=j ) pLoop->u.btree.nIdxCol = j+1;
isMatch = 1;
break;
}
@@ -4850,53 +4853,20 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
if( pLevel->op!=OP_Noop ){
#ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
int addrSeek = 0;
int n = -1;
int j, k, op;
int r1 = pParse->nMem+1;
Index *pIdx;
int n;
if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED
&& (pLoop->wsFlags & WHERE_INDEXED)!=0
&& OptimizationEnabled(db, SQLITE_SkipAhead)
&& (pIdx = pLoop->u.btree.pIndex)->hasStat1
&& pIdx->aiRowLogEst[(n = pLoop->u.btree.nIdxCol)-1]>=36
){
/* This is the Skip-ahead optimization. When doing a DISTINCT query
** that has WHERE_DISTINCT_ORDERED, use OP_SkipGT/OP_SkipLT to skip
** over all duplicate entries, rather than visiting all duplicates
** using OP_Next/OP_Prev. */
ExprList *pX = pWInfo->pResultSet;
for(j=0; j<pX->nExpr; j++){
Expr *pE = sqlite3ExprSkipCollate(pX->a[j].pExpr);
if( pE->op==TK_COLUMN ){
if( pE->iTable==pLevel->iIdxCur ){
k = pE->iColumn+1;
}else{
if( pE->iTable!=pLevel->iTabCur ) continue;
k = 1+sqlite3ColumnOfIndex(pIdx, pE->iColumn);
}
if( k>n ) n = k;
}
#ifdef SQLITE_DEBUG
/* Any expressions in the result-set that match columns of the
** index should have already been transformed to TK_COLUMN
** operations by whereIndexExprTrans(). */
else if( pIdx->aColExpr ){
for(k=0; k<pIdx->nKeyCol; k++){
Expr *pI = pIdx->aColExpr->a[k].pExpr;
assert( pI==0 || sqlite3ExprCompare(pE, pI, pE->iTable)!=0 );
}
}
#endif
}
}
/* TUNING: Only try to skip ahead using OP_Seek if we expect to
** skip over 11 or more rows. Otherwise, OP_Next is just as fast.
*/
assert( 36==sqlite3LogEst(12) );
if( n>0 && pIdx->aiRowLogEst[n]>=36 ){
int r1 = pParse->nMem+1;
int j, op;
for(j=0; j<n; j++){
sqlite3VdbeAddOp3(v, OP_Column, pLevel->iIdxCur, j, r1+j);
}
pParse->nMem += n;
pParse->nMem += n+1;
op = pLevel->op==OP_Prev ? OP_SeekLT : OP_SeekGT;
addrSeek = sqlite3VdbeAddOp4Int(v, op, pLevel->iIdxCur, 0, r1, n);
VdbeCoverageIf(v, op==OP_SeekLT);