diff options
Diffstat (limited to 'src/backend/optimizer/plan/initsplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/initsplan.c | 95 |
1 files changed, 77 insertions, 18 deletions
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c index 9cfc56ea541..24185a6cecb 100644 --- a/src/backend/optimizer/plan/initsplan.c +++ b/src/backend/optimizer/plan/initsplan.c @@ -52,9 +52,12 @@ static void distribute_qual_to_rels(PlannerInfo *root, Node *clause, JoinType jointype, Relids qualscope, Relids ojscope, - Relids outerjoin_nonnullable); + Relids outerjoin_nonnullable, + Relids deduced_nullable_relids); static bool check_outerjoin_delay(PlannerInfo *root, Relids *relids_p, Relids *nullable_relids_p, bool is_pushed_down); +static bool check_equivalence_delay(PlannerInfo *root, + RestrictInfo *restrictinfo); static bool check_redundant_nullability_qual(PlannerInfo *root, Node *clause); static void check_mergejoinable(RestrictInfo *restrictinfo); static void check_hashjoinable(RestrictInfo *restrictinfo); @@ -353,7 +356,7 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join, distribute_qual_to_rels(root, qual, false, below_outer_join, JOIN_INNER, - *qualscope, NULL, NULL); + *qualscope, NULL, NULL, NULL); } } else if (IsA(jtnode, JoinExpr)) @@ -477,7 +480,7 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join, distribute_qual_to_rels(root, qual, false, below_outer_join, j->jointype, *qualscope, - ojscope, nonnullable_rels); + ojscope, nonnullable_rels, NULL); } /* Now we can add the SpecialJoinInfo to join_info_list */ @@ -786,13 +789,19 @@ make_outerjoininfo(PlannerInfo *root, * baserels appearing on the outer (nonnullable) side of the join * (for FULL JOIN this includes both sides of the join, and must in fact * equal qualscope) + * 'deduced_nullable_relids': if is_deduced is TRUE, the nullable relids to + * impute to the clause; otherwise NULL * * 'qualscope' identifies what level of JOIN the qual came from syntactically. * 'ojscope' is needed if we decide to force the qual up to the outer-join * level, which will be ojscope not necessarily qualscope. * - * At the time this is called, root->join_info_list must contain entries for - * all and only those special joins that are syntactically below this qual. + * In normal use (when is_deduced is FALSE), at the time this is called, + * root->join_info_list must contain entries for all and only those special + * joins that are syntactically below this qual. But when is_deduced is TRUE, + * we are adding new deduced clauses after completion of deconstruct_jointree, + * so it cannot be assumed that root->join_info_list has anything to do with + * qual placement. */ static void distribute_qual_to_rels(PlannerInfo *root, Node *clause, @@ -801,7 +810,8 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause, JoinType jointype, Relids qualscope, Relids ojscope, - Relids outerjoin_nonnullable) + Relids outerjoin_nonnullable, + Relids deduced_nullable_relids) { Relids relids; bool is_pushed_down; @@ -914,12 +924,13 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause, * If the qual came from implied-equality deduction, it should not be * outerjoin-delayed, else deducer blew it. But we can't check this * because the join_info_list may now contain OJs above where the qual - * belongs. + * belongs. For the same reason, we must rely on caller to supply the + * correct nullable_relids set. */ Assert(!ojscope); is_pushed_down = true; outerjoin_delayed = false; - nullable_relids = NULL; + nullable_relids = deduced_nullable_relids; /* Don't feed it back for more deductions */ maybe_equivalence = false; maybe_outer_join = false; @@ -1089,7 +1100,8 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause, { if (maybe_equivalence) { - if (process_equivalence(root, restrictinfo, below_outer_join)) + if (check_equivalence_delay(root, restrictinfo) && + process_equivalence(root, restrictinfo, below_outer_join)) return; /* EC rejected it, so set left_ec/right_ec the hard way ... */ initialize_mergeclause_eclasses(root, restrictinfo); @@ -1262,6 +1274,44 @@ check_outerjoin_delay(PlannerInfo *root, } /* + * check_equivalence_delay + * Detect whether a potential equivalence clause is rendered unsafe + * by outer-join-delay considerations. Return TRUE if it's safe. + * + * The initial tests in distribute_qual_to_rels will consider a mergejoinable + * clause to be a potential equivalence clause if it is not outerjoin_delayed. + * But since the point of equivalence processing is that we will recombine the + * two sides of the clause with others, we have to check that each side + * satisfies the not-outerjoin_delayed condition on its own; otherwise it might + * not be safe to evaluate everywhere we could place a derived equivalence + * condition. + */ +static bool +check_equivalence_delay(PlannerInfo *root, + RestrictInfo *restrictinfo) +{ + Relids relids; + Relids nullable_relids; + + /* fast path if no special joins */ + if (root->join_info_list == NIL) + return true; + + /* must copy restrictinfo's relids to avoid changing it */ + relids = bms_copy(restrictinfo->left_relids); + /* check left side does not need delay */ + if (check_outerjoin_delay(root, &relids, &nullable_relids, true)) + return false; + + /* and similarly for the right side */ + relids = bms_copy(restrictinfo->right_relids); + if (check_outerjoin_delay(root, &relids, &nullable_relids, true)) + return false; + + return true; +} + +/* * check_redundant_nullability_qual * Check to see if the qual is an IS NULL qual that is redundant with * a lower JOIN_ANTI join. @@ -1371,11 +1421,20 @@ distribute_restrictinfo_to_rels(PlannerInfo *root, * variable-free. Otherwise the qual is applied at the lowest join level * that provides all its variables. * + * "nullable_relids" is the set of relids used in the expressions that are + * potentially nullable below the expressions. (This has to be supplied by + * caller because this function is used after deconstruct_jointree, so we + * don't have knowledge of where the clause items came from.) + * * "both_const" indicates whether both items are known pseudo-constant; * in this case it is worth applying eval_const_expressions() in case we * can produce constant TRUE or constant FALSE. (Otherwise it's not, * because the expressions went through eval_const_expressions already.) * + * Note: this function will copy item1 and item2, but it is caller's + * responsibility to make sure that the Relids parameters are fresh copies + * not shared with other uses. + * * This is currently used only when an EquivalenceClass is found to * contain pseudoconstants. See path/pathkeys.c for more details. */ @@ -1386,6 +1445,7 @@ process_implied_equality(PlannerInfo *root, Expr *item1, Expr *item2, Relids qualscope, + Relids nullable_relids, bool below_outer_join, bool both_const) { @@ -1419,15 +1479,12 @@ process_implied_equality(PlannerInfo *root, } } - /* Make a copy of qualscope to avoid problems if source EC changes */ - qualscope = bms_copy(qualscope); - /* * Push the new clause into all the appropriate restrictinfo lists. */ distribute_qual_to_rels(root, (Node *) clause, true, below_outer_join, JOIN_INNER, - qualscope, NULL, NULL); + qualscope, NULL, NULL, nullable_relids); } /* @@ -1436,6 +1493,10 @@ process_implied_equality(PlannerInfo *root, * This overlaps the functionality of process_implied_equality(), but we * must return the RestrictInfo, not push it into the joininfo tree. * + * Note: this function will copy item1 and item2, but it is caller's + * responsibility to make sure that the Relids parameters are fresh copies + * not shared with other uses. + * * Note: we do not do initialize_mergeclause_eclasses() here. It is * caller's responsibility that left_ec/right_ec be set as necessary. */ @@ -1444,7 +1505,8 @@ build_implied_join_equality(Oid opno, Oid collation, Expr *item1, Expr *item2, - Relids qualscope) + Relids qualscope, + Relids nullable_relids) { RestrictInfo *restrictinfo; Expr *clause; @@ -1461,9 +1523,6 @@ build_implied_join_equality(Oid opno, InvalidOid, collation); - /* Make a copy of qualscope to avoid problems if source EC changes */ - qualscope = bms_copy(qualscope); - /* * Build the RestrictInfo node itself. */ @@ -1472,7 +1531,7 @@ build_implied_join_equality(Oid opno, false, /* outerjoin_delayed */ false, /* pseudoconstant */ qualscope, /* required_relids */ - NULL); /* nullable_relids */ + nullable_relids); /* nullable_relids */ /* Set mergejoinability/hashjoinability flags */ check_mergejoinable(restrictinfo); |