diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/plan/planagg.c | 42 |
1 files changed, 32 insertions, 10 deletions
diff --git a/src/backend/optimizer/plan/planagg.c b/src/backend/optimizer/plan/planagg.c index 16d71af183d..80d01c02946 100644 --- a/src/backend/optimizer/plan/planagg.c +++ b/src/backend/optimizer/plan/planagg.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.32 2007/04/27 22:05:47 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.33 2007/10/13 00:58:03 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -22,6 +22,7 @@ #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/planmain.h" +#include "optimizer/predtest.h" #include "optimizer/subselect.h" #include "parser/parse_clause.h" #include "parser/parse_expr.h" @@ -35,6 +36,7 @@ typedef struct Oid aggfnoid; /* pg_proc Oid of the aggregate */ Oid aggsortop; /* Oid of its sort operator */ Expr *target; /* expression we are aggregating on */ + Expr *notnulltest; /* expression for "target IS NOT NULL" */ IndexPath *path; /* access path for index scan */ Cost pathcost; /* estimated cost to fetch first row */ bool nulls_first; /* null ordering direction matching index */ @@ -285,8 +287,23 @@ build_minmax_path(PlannerInfo *root, RelOptInfo *rel, MinMaxAggInfo *info) IndexPath *best_path = NULL; Cost best_cost = 0; bool best_nulls_first = false; + NullTest *ntest; + List *allquals; ListCell *l; + /* Build "target IS NOT NULL" expression for use below */ + ntest = makeNode(NullTest); + ntest->nulltesttype = IS_NOT_NULL; + ntest->arg = copyObject(info->target); + info->notnulltest = (Expr *) ntest; + + /* + * Build list of existing restriction clauses plus the notnull test. + * We cheat a bit by not bothering with a RestrictInfo node for the + * notnull test --- predicate_implied_by() won't care. + */ + allquals = list_concat(list_make1(ntest), rel->baserestrictinfo); + foreach(l, rel->indexlist) { IndexOptInfo *index = (IndexOptInfo *) lfirst(l); @@ -302,8 +319,13 @@ build_minmax_path(PlannerInfo *root, RelOptInfo *rel, MinMaxAggInfo *info) if (index->relam != BTREE_AM_OID) continue; - /* Ignore partial indexes that do not match the query */ - if (index->indpred != NIL && !index->predOK) + /* + * Ignore partial indexes that do not match the query --- unless + * their predicates can be proven from the baserestrict list plus + * the IS NOT NULL test. In that case we can use them. + */ + if (index->indpred != NIL && !index->predOK && + !predicate_implied_by(index->indpred, allquals)) continue; /* @@ -441,7 +463,6 @@ make_agg_subplan(PlannerInfo *root, MinMaxAggInfo *info) Plan *iplan; TargetEntry *tle; SortClause *sortcl; - NullTest *ntest; /* * Generate a suitably modified query. Much of the work here is probably @@ -487,7 +508,7 @@ make_agg_subplan(PlannerInfo *root, MinMaxAggInfo *info) * basic indexscan, but we have to convert it to a Plan and attach a LIMIT * node above it. * - * Also we must add a "WHERE foo IS NOT NULL" restriction to the + * Also we must add a "WHERE target IS NOT NULL" restriction to the * indexscan, to be sure we don't return a NULL, which'd be contrary to * the standard behavior of MIN/MAX. XXX ideally this should be done * earlier, so that the selectivity of the restriction could be included @@ -497,6 +518,9 @@ make_agg_subplan(PlannerInfo *root, MinMaxAggInfo *info) * The NOT NULL qual has to go on the actual indexscan; create_plan might * have stuck a gating Result atop that, if there were any pseudoconstant * quals. + * + * We can skip adding the NOT NULL qual if it's redundant with either + * an already-given WHERE condition, or a clause of the index predicate. */ plan = create_plan(&subroot, (Path *) info->path); @@ -508,11 +532,9 @@ make_agg_subplan(PlannerInfo *root, MinMaxAggInfo *info) iplan = plan; Assert(IsA(iplan, IndexScan)); - ntest = makeNode(NullTest); - ntest->nulltesttype = IS_NOT_NULL; - ntest->arg = copyObject(info->target); - - iplan->qual = lcons(ntest, iplan->qual); + if (!list_member(iplan->qual, info->notnulltest) && + !list_member(info->path->indexinfo->indpred, info->notnulltest)) + iplan->qual = lcons(info->notnulltest, iplan->qual); plan = (Plan *) make_limit(plan, subparse->limitOffset, |