diff options
Diffstat (limited to 'src/where.c')
| -rw-r--r-- | src/where.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/src/where.c b/src/where.c index fe76f2c96..a4506602a 100644 --- a/src/where.c +++ b/src/where.c @@ -5561,15 +5561,15 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){ ** Except, if the first solver() call generated a full-table scan in an outer ** loop then stop this analysis at the first full-scan, since the second ** solver() run might try to swap that full-scan for another in order to -** get the output into the correct order. In other words, we do *not* want -** to inhibit a rewrites like this: +** get the output into the correct order. In other words, we allow a +** rewrite like this: ** ** First Solver() Second Solver() ** |-- SCAN t1 |-- SCAN t2 ** |-- SEARCH t2 `-- SEARCH t1 ** `-- SORT USING B-TREE ** -** Rather, the purpose of this routine is to inhibit rewrites such as: +** The purpose of this routine is to disallow rewrites such as: ** ** First Solver() Second Solver() ** |-- SEARCH t1 |-- SCAN t2 <--- bad! @@ -5581,6 +5581,9 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){ */ static SQLITE_NOINLINE void whereInterstageHeuristic(WhereInfo *pWInfo){ int i; +#ifdef WHERETRACE_ENABLED + int once = 0; +#endif for(i=0; i<pWInfo->nLevel; i++){ WhereLoop *p = pWInfo->a[i].pWLoop; if( p==0 ) break; @@ -5590,7 +5593,19 @@ static SQLITE_NOINLINE void whereInterstageHeuristic(WhereInfo *pWInfo){ WhereLoop *pLoop; for(pLoop=pWInfo->pLoops; pLoop; pLoop=pLoop->pNextLoop){ if( pLoop->iTab!=iTab ) continue; - if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0 ) continue; + if( (pLoop->wsFlags & (WHERE_CONSTRAINT|WHERE_AUTO_INDEX))!=0 ){ + /* Auto-index and index-constrained loops allowed to remain */ + continue; + } +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace & 0x80 ){ + if( once==0 ){ + sqlite3DebugPrintf("Loops disabled by interstage heuristic:\n"); + once = 1; + } + sqlite3WhereLoopPrint(pLoop, &pWInfo->sWC); + } +#endif /* WHERETRACE_ENABLED */ pLoop->prereq = ALLBITS; /* Prevent 2nd solver() from using this one */ } }else{ |