diff options
Diffstat (limited to 'src/backend/optimizer/plan/planagg.c')
| -rw-r--r-- | src/backend/optimizer/plan/planagg.c | 34 |
1 files changed, 24 insertions, 10 deletions
diff --git a/src/backend/optimizer/plan/planagg.c b/src/backend/optimizer/plan/planagg.c index b80f2c6900b..9c3b151f201 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 1.2 2005/04/12 04:26:24 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.3 2005/04/12 05:11:28 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -185,6 +185,8 @@ optimize_minmax_aggregates(Query *root, List *tlist, Path *best_path) { Assert(((ResultPath *) best_path)->subpath != NULL); constant_quals = ((ResultPath *) best_path)->constantqual; + /* no need to do this more than once: */ + constant_quals = order_qual_clauses(root, constant_quals); } else constant_quals = NIL; @@ -438,10 +440,10 @@ static void make_agg_subplan(Query *root, MinMaxAggInfo *info, List *constant_quals) { Query *subquery; - Path *path; Plan *plan; TargetEntry *tle; SortClause *sortcl; + NullTest *ntest; /* * Generate a suitably modified Query node. Much of the work here is @@ -482,18 +484,30 @@ make_agg_subplan(Query *root, MinMaxAggInfo *info, List *constant_quals) * Generate the plan for the subquery. We already have a Path for * the basic indexscan, but we have to convert it to a Plan and * attach a LIMIT node above it. We might need a gating Result, too, - * which is most easily added at the Path stage. + * to handle any non-variable qual clauses. + * + * Also we must add a "WHERE foo 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 in our cost estimates. But that looks painful, and in + * most cases the fraction of NULLs isn't high enough to change the + * decision. */ - path = (Path *) info->path; + plan = create_plan(subquery, (Path *) info->path); - if (constant_quals) - path = (Path *) create_result_path(NULL, - path, - copyObject(constant_quals)); + plan->targetlist = copyObject(subquery->targetList); - plan = create_plan(subquery, path); + ntest = makeNode(NullTest); + ntest->nulltesttype = IS_NOT_NULL; + ntest->arg = copyObject(info->target); - plan->targetlist = copyObject(subquery->targetList); + plan->qual = lappend(plan->qual, ntest); + + if (constant_quals) + plan = (Plan *) make_result(copyObject(plan->targetlist), + copyObject(constant_quals), + plan); plan = (Plan *) make_limit(plan, subquery->limitOffset, |