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Make sure that disabling the covering index scan optimization does not

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prevent a covering index from being used to satisfy an ORDER BY clause.

FossilOrigin-Name: e8b7ea8202c443bfc8a978588c7d2cfaa14a8fea
This commit is contained in:
drh
2013-06-13 17:28:22 +00:00
parent bbe8b24b8d
commit 53cfbe92d1
3 changed files with 18 additions and 15 deletions
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19
src/where.c
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@@ -445,7 +445,6 @@ struct WhereInfo {
#define WHERE_ONEROW 0x00001000 /* Selects no more than one row */
#define WHERE_MULTI_OR 0x00002000 /* OR using multiple indices */
#define WHERE_TEMP_INDEX 0x00004000 /* Uses an ephemeral index */
#define WHERE_COVER_SCAN 0x00008000 /* Full scan of a covering index */
/* Convert a WhereCost value (10 times log2(X)) into its integer value X.
@@ -3614,8 +3613,7 @@ static Bitmask codeOneLoopStart(
pLevel->op = OP_Next;
}
pLevel->p1 = iIdxCur;
if( (pLoop->wsFlags & (WHERE_COLUMN_EQ | WHERE_COLUMN_RANGE |
WHERE_COLUMN_NULL | WHERE_COLUMN_IN))==0 ){
if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){
pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
}else{
assert( pLevel->p5==0 );
@@ -4375,6 +4373,7 @@ static int indexMightHelpWithOrderBy(
int iCol;
int ii;
if( pIndex->bUnordered ) return 0;
if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
iCol = pIndex->aiColumn[0];
for(ii=0; ii<pOB->nExpr; ii++){
@@ -4503,6 +4502,8 @@ static int whereLoopAddBtree(
pNew->prereq = mExtra;
pNew->u.btree.pIndex = pProbe;
b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor);
/* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 );
if( pProbe->tnum<=0 ){
/* Integer primary key index */
pNew->wsFlags = WHERE_IPK;
@@ -4523,11 +4524,13 @@ static int whereLoopAddBtree(
pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;
/* Full scan via index */
if( (m==0 || b)
&& pProbe->bUnordered==0
&& (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
&& sqlite3GlobalConfig.bUseCis
&& OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan)
if( b
|| ( m==0
&& pProbe->bUnordered==0
&& (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
&& sqlite3GlobalConfig.bUseCis
&& OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan)
)
){
pNew->iSortIdx = b ? iSortIdx : 0;
pNew->nOut = rSize;