diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/where.c | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/src/where.c b/src/where.c index d32997d06..ae9bf85fa 100644 --- a/src/where.c +++ b/src/where.c @@ -4065,6 +4065,7 @@ WhereInfo *sqlite3WhereBegin( Bitmask m; /* Bitmask value for j or bestJ */ int isOptimal; /* Iterator for optimal/non-optimal search */ int nUnconstrained; /* Number tables without INDEXED BY */ + Bitmask notIndexed; /* Mask of tables that cannot use an index */ memset(&bestPlan, 0, sizeof(bestPlan)); bestPlan.rCost = SQLITE_BIG_DBL; @@ -4107,8 +4108,9 @@ WhereInfo *sqlite3WhereBegin( ** costlier approach. */ nUnconstrained = 0; + notIndexed = 0; for(isOptimal=(iFrom<nTabList-1); isOptimal>=0; isOptimal--){ - Bitmask mask; /* Mask of tables not yet ready */ + Bitmask mask; /* Mask of tables not yet ready */ for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){ int doNotReorder; /* True if this table should not be reordered */ WhereCost sCost; /* Cost information from best[Virtual]Index() */ @@ -4137,28 +4139,43 @@ WhereInfo *sqlite3WhereBegin( } assert( isOptimal || (sCost.used¬Ready)==0 ); + /* If an INDEXED BY clause is present, then the plan must use that + ** index if it uses any index at all */ + assert( pTabItem->pIndex==0 + || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 + || sCost.plan.u.pIdx==pTabItem->pIndex ); + + if( isOptimal && (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){ + notIndexed |= m; + } + /* Conditions under which this table becomes the best so far: ** ** (1) The table must not depend on other tables that have not ** yet run. ** ** (2) A full-table-scan plan cannot supercede another plan unless - ** the full-table-scan is an optimal plan. + ** it is an "optimal" plan as defined above. ** - ** (3) The plan cost must be lower than prior plans or else the - ** cost must be the same and the number of rows must be lower. - ** - ** (4) All tables have an INDEXED BY clause or this table lacks an + ** (3) All tables have an INDEXED BY clause or this table lacks an ** INDEXED BY clause or this table uses the specific - ** index specified by its INDEXED BY clause. + ** index specified by its INDEXED BY clause. This rule ensures + ** that a best-so-far is always selected even if an impossible + ** combination of INDEXED BY clauses are given. The error + ** will be detected and relayed back to the application later. + ** The NEVER() comes about because rule (2) above prevents + ** An indexable full-table-scan from reaching rule (3). + ** + ** (4) The plan cost must be lower than prior plans or else the + ** cost must be the same and the number of rows must be lower. */ if( (sCost.used¬Ready)==0 /* (1) */ - && (bestJ<0 || isOptimal /* (2) */ + && (bestJ<0 || (notIndexed&m)!=0 /* (2) */ || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0) - && (bestJ<0 || sCost.rCost<bestPlan.rCost /* (3) */ + && (nUnconstrained==0 || pTabItem->pIndex==0 /* (3) */ + || NEVER((sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0)) + && (bestJ<0 || sCost.rCost<bestPlan.rCost /* (4) */ || (sCost.rCost<=bestPlan.rCost && sCost.nRow<bestPlan.nRow)) - && (nUnconstrained==0 || pTabItem->pIndex==0 /* (4) */ - || pTabItem->pIndex==sCost.plan.u.pIdx) ){ WHERETRACE(("... best so far with cost=%g and nRow=%g\n", sCost.rCost, sCost.nRow)); |