diff options
Diffstat (limited to 'src/backend/optimizer/plan/analyzejoins.c')
| -rw-r--r-- | src/backend/optimizer/plan/analyzejoins.c | 52 |
1 files changed, 30 insertions, 22 deletions
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c index 1ca554a6430..5bcf95cef3e 100644 --- a/src/backend/optimizer/plan/analyzejoins.c +++ b/src/backend/optimizer/plan/analyzejoins.c @@ -217,12 +217,12 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) /* * 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 as - * non-lateral references. Note that if the PHV's syntactic scope is just - * the inner rel, we can't drop the rel even if the PHV is variable-free. + * that will be used above the join. The PHV case is a little bit more + * complicated, because PHVs may have been assigned a ph_eval_at location + * that includes the innerrel, yet their contained expression might not + * actually reference the innerrel (it could be just a constant, for + * instance). If such a PHV is due to be evaluated above the join then it + * needn't prevent join removal. */ foreach(l, root->placeholder_list) { @@ -230,15 +230,23 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) if (bms_overlap(phinfo->ph_lateral, innerrel->relids)) return false; /* it references innerrel laterally */ - if (bms_is_subset(phinfo->ph_needed, inputrelids)) - 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_is_subset(phinfo->ph_eval_at, innerrel->relids)) + if (bms_is_subset(phinfo->ph_needed, inputrelids)) + continue; /* PHV is not used above the join */ + if (!bms_is_member(sjinfo->ojrelid, phinfo->ph_eval_at)) + return false; /* it has to be evaluated below the join */ + + /* + * We need to be sure there will still be a place to evaluate the PHV + * if we remove the join, ie that ph_eval_at wouldn't become empty. + */ + if (!bms_overlap(sjinfo->min_lefthand, phinfo->ph_eval_at)) return false; /* there isn't any other place to eval PHV */ + /* Check contained expression last, since this is a bit expensive */ if (bms_overlap(pull_varnos(root, (Node *) phinfo->ph_var->phexpr), innerrel->relids)) - return false; /* it does reference innerrel */ + return false; /* contained expression references innerrel */ } /* @@ -270,15 +278,7 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) * be from WHERE, for example). */ if (RINFO_IS_PUSHED_DOWN(restrictinfo, joinrelids)) - { - /* - * If such a clause actually references the inner rel then join - * removal has to be disallowed. The previous attr_needed checks - * should have caught this, though. - */ - Assert(!bms_is_member(innerrelid, restrictinfo->clause_relids)); continue; /* ignore; not useful here */ - } /* Ignore if it's not a mergejoinable clause */ if (!restrictinfo->can_join || @@ -465,13 +465,21 @@ remove_rel_from_query(PlannerInfo *root, int relid, int ojrelid, */ if (bms_is_member(ojrelid, rinfo->required_relids)) { - /* Recheck that qual doesn't actually reference the target rel */ - Assert(!bms_is_member(relid, rinfo->clause_relids)); - /* - * The required_relids probably aren't shared with anything else, + * There might be references to relid or ojrelid in the + * clause_relids as a consequence of PHVs having ph_eval_at sets + * that include those. We already checked above that any such PHV + * is safe, so we can just drop those references. + * + * The clause_relids probably aren't shared with anything else, * but let's copy them just to be sure. */ + rinfo->clause_relids = bms_copy(rinfo->clause_relids); + rinfo->clause_relids = bms_del_member(rinfo->clause_relids, + relid); + rinfo->clause_relids = bms_del_member(rinfo->clause_relids, + ojrelid); + /* Likewise for required_relids */ rinfo->required_relids = bms_copy(rinfo->required_relids); rinfo->required_relids = bms_del_member(rinfo->required_relids, relid); |