diff options
Diffstat (limited to 'src/backend/optimizer/path/costsize.c')
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 783dca8a4ac..94077e6a006 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -4570,10 +4570,24 @@ cost_subplan(PlannerInfo *root, SubPlan *subplan, Plan *plan) { QualCost sp_cost; - /* Figure any cost for evaluating the testexpr */ + /* + * Figure any cost for evaluating the testexpr. + * + * Usually, SubPlan nodes are built very early, before we have constructed + * any RelOptInfos for the parent query level, which means the parent root + * does not yet contain enough information to safely consult statistics. + * Therefore, we pass root as NULL here. cost_qual_eval() is already + * well-equipped to handle a NULL root. + * + * One exception is SubPlan nodes built for the initplans of MIN/MAX + * aggregates from indexes (cf. SS_make_initplan_from_plan). In this + * case, having a NULL root is safe because testexpr will be NULL. + * Besides, an initplan will by definition not consult anything from the + * parent plan. + */ cost_qual_eval(&sp_cost, make_ands_implicit((Expr *) subplan->testexpr), - root); + NULL); if (subplan->useHashTable) { |