From 7fc8db849106db91e1053ed25045eb4fa877f212 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 25 Sep 2010 19:04:02 -0400 Subject: Fix another join removal bug: the check on PlaceHolderVars was wrong. The previous coding would decide that join removal was unsafe upon finding a PlaceHolderVar that needed to be evaluated at the inner rel and then used above the join. However, this fails to cover the case of PlaceHolderVars that refer to both the inner rel and some other rels. Per bug report from Andrus. --- src/backend/optimizer/plan/analyzejoins.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'src/backend/optimizer/plan/analyzejoins.c') diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c index 5fc056e2a57..1355c18317a 100644 --- a/src/backend/optimizer/plan/analyzejoins.c +++ b/src/backend/optimizer/plan/analyzejoins.c @@ -26,6 +26,7 @@ #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/planmain.h" +#include "optimizer/var.h" /* local functions */ static bool join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo); @@ -197,16 +198,23 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) } /* - * Similarly check that the inner rel doesn't produce any PlaceHolderVars - * that will be used above the join. + * Similarly check that the inner rel isn't needed by any PlaceHolderVars + * that will be used above the join. We only need to fail if such a PHV + * actually references some inner-rel attributes; but the correct check + * for that is relatively expensive, so we first check against ph_eval_at, + * which must mention the inner rel if the PHV uses any inner-rel attrs. */ foreach(l, root->placeholder_list) { PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l); - if (bms_is_subset(phinfo->ph_eval_at, innerrel->relids) && - !bms_is_subset(phinfo->ph_needed, joinrelids)) - return false; + if (bms_is_subset(phinfo->ph_needed, joinrelids)) + continue; /* PHV is not used above the join */ + if (!bms_overlap(phinfo->ph_eval_at, innerrel->relids)) + continue; /* it definitely doesn't reference innerrel */ + if (bms_overlap(pull_varnos((Node *) phinfo->ph_var), + innerrel->relids)) + return false; /* it does reference innerrel */ } /* -- cgit v1.2.3