From c14066aa7049bac14cadc18d0c48bcf6ea81ff52 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 31 Jul 2007 19:54:27 +0000 Subject: [PATCH] Fix a bug in the original implementation of redundant-join-clause removal: clauses in which one side or the other references both sides of the join cannot be removed as redundant, because that expression won't have been constrained below the join. Per report from Sergey Burladyan. --- src/backend/optimizer/path/indxpath.c | 6 ++- src/backend/optimizer/plan/createplan.c | 4 +- src/backend/optimizer/util/relnode.c | 7 ++- src/backend/optimizer/util/restrictinfo.c | 57 ++++++++++++++++++----- src/include/optimizer/restrictinfo.h | 6 ++- src/test/regress/expected/join.out | 16 +++++++ src/test/regress/sql/join.sql | 16 +++++++ 7 files changed, 94 insertions(+), 18 deletions(-) diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c index 28182c2372..0403fd4c92 100644 --- a/src/backend/optimizer/path/indxpath.c +++ b/src/backend/optimizer/path/indxpath.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.147.4.2 2005/12/06 16:59:22 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.147.4.3 2007/07/31 19:54:26 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -656,7 +656,9 @@ group_clauses_by_indexkey_for_join(Query *root, List *nl; nl = remove_redundant_join_clauses(root, - FastListValue(&clausegroup), + FastListValue(&clausegroup), + outer_relids, + rel->relids, jointype); FastListFromList(&clausegroup, nl); } diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index bbbc013fff..a28d195e41 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.157.2.3 2004/02/29 17:36:48 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.157.2.4 2007/07/31 19:54:26 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -927,6 +927,8 @@ create_nestloop_plan(Query *root, select_nonredundant_join_clauses(root, joinrestrictclauses, lfirst(indexjoinclauses), + best_path->outerjoinpath->parent->relids, + best_path->innerjoinpath->parent->relids, best_path->jointype); } } diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c index ea15e20f2b..6ad2e82319 100644 --- a/src/backend/optimizer/util/relnode.c +++ b/src/backend/optimizer/util/relnode.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.52.4.1 2003/12/08 18:20:10 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.52.4.2 2007/07/31 19:54:27 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -466,7 +466,10 @@ build_joinrel_restrictlist(Query *root, * previous clauses (see optimizer/README for discussion). We detect * that case and omit the redundant clause from the result list. */ - result = remove_redundant_join_clauses(root, rlist, jointype); + result = remove_redundant_join_clauses(root, rlist, + outer_rel->relids, + inner_rel->relids, + jointype); freeList(rlist); diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c index 0c21e94e68..d3aa8098bd 100644 --- a/src/backend/optimizer/util/restrictinfo.c +++ b/src/backend/optimizer/util/restrictinfo.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.19 2003/08/04 02:40:01 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.19.4.1 2007/07/31 19:54:27 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -23,6 +23,8 @@ static bool join_clause_is_redundant(Query *root, RestrictInfo *rinfo, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype); @@ -105,6 +107,8 @@ get_actual_join_clauses(List *restrictinfo_list, */ List * remove_redundant_join_clauses(Query *root, List *restrictinfo_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype) { List *result = NIL; @@ -115,7 +119,9 @@ remove_redundant_join_clauses(Query *root, List *restrictinfo_list, RestrictInfo *rinfo = (RestrictInfo *) lfirst(item); /* drop it if redundant with any prior clause */ - if (join_clause_is_redundant(root, rinfo, result, jointype)) + if (join_clause_is_redundant(root, rinfo, result, + outer_relids, inner_relids, + jointype)) continue; /* otherwise, add it to result list */ @@ -143,6 +149,8 @@ List * select_nonredundant_join_clauses(Query *root, List *restrictinfo_list, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype) { List *result = NIL; @@ -153,7 +161,9 @@ select_nonredundant_join_clauses(Query *root, RestrictInfo *rinfo = (RestrictInfo *) lfirst(item); /* drop it if redundant with any reference clause */ - if (join_clause_is_redundant(root, rinfo, reference_list, jointype)) + if (join_clause_is_redundant(root, rinfo, reference_list, + outer_relids, inner_relids, + jointype)) continue; /* otherwise, add it to result list */ @@ -185,6 +195,12 @@ select_nonredundant_join_clauses(Query *root, * of the latter, even though they might seem redundant by the pathkey * membership test. * + * Also, we cannot eliminate clauses wherein one side mentions vars from + * both relations, as in "WHERE t1.f1 = t2.f1 AND t1.f1 = t1.f2 - t2.f2". + * In this example, "t1.f2 - t2.f2" could not have been computed at all + * before forming the join of t1 and t2, so it certainly wasn't constrained + * earlier. + * * Weird special case: if we have two clauses that seem redundant * except one is pushed down into an outer join and the other isn't, * then they're not really redundant, because one constrains the @@ -194,6 +210,8 @@ static bool join_clause_is_redundant(Query *root, RestrictInfo *rinfo, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype) { /* always consider exact duplicates redundant */ @@ -228,16 +246,31 @@ join_clause_is_redundant(Query *root, if (redundant) { /* - * It looks redundant, now check for "var = const" case. If - * left_relids/right_relids are set, then there are definitely - * vars on both sides; else we must check the hard way. + * It looks redundant, now check for special cases. This is + * ugly and slow because of the mistaken decision to not set + * left_relids/right_relids all the time, as 8.0 and up do. + * Not going to change that in 7.x though. */ - if (rinfo->left_relids) - return true; /* var = var, so redundant */ - if (contain_var_clause(get_leftop(rinfo->clause)) && - contain_var_clause(get_rightop(rinfo->clause))) - return true; /* var = var, so redundant */ - /* else var = const, not redundant */ + Relids left_relids = rinfo->left_relids; + Relids right_relids = rinfo->right_relids; + + if (left_relids == NULL) + left_relids = pull_varnos(get_leftop(rinfo->clause)); + if (right_relids == NULL) + right_relids = pull_varnos(get_rightop(rinfo->clause)); + + if (bms_is_empty(left_relids) || bms_is_empty(right_relids)) + return false; /* var = const, so not redundant */ + + /* check for either side mentioning both rels */ + if (bms_overlap(left_relids, outer_relids) && + bms_overlap(left_relids, inner_relids)) + return false; /* clause LHS uses both, so not redundant */ + if (bms_overlap(right_relids, outer_relids) && + bms_overlap(right_relids, inner_relids)) + return false; /* clause RHS uses both, so not redundant */ + + return true; /* else it really is redundant */ } } diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h index 3e7dc9edd9..6b4c8c6217 100644 --- a/src/include/optimizer/restrictinfo.h +++ b/src/include/optimizer/restrictinfo.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: restrictinfo.h,v 1.19 2003/08/04 02:40:14 momjian Exp $ + * $Id: restrictinfo.h,v 1.19.4.1 2007/07/31 19:54:27 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -22,10 +22,14 @@ extern void get_actual_join_clauses(List *restrictinfo_list, List **joinquals, List **otherquals); extern List *remove_redundant_join_clauses(Query *root, List *restrictinfo_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype); extern List *select_nonredundant_join_clauses(Query *root, List *restrictinfo_list, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype); #endif /* RESTRICTINFO_H */ diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out index 7a1da6799e..ff48b4ed3f 100644 --- a/src/test/regress/expected/join.out +++ b/src/test/regress/expected/join.out @@ -2147,3 +2147,19 @@ DROP TABLE t2; DROP TABLE t3; DROP TABLE J1_TBL; DROP TABLE J2_TBL; +-- +-- regression test for problems of the sort depicted in bug #3494 +-- +create temp table tt5(f1 int, f2 int); +create temp table tt6(f1 int, f2 int); +insert into tt5 values(1, 10); +insert into tt5 values(1, 11); +insert into tt6 values(1, 9); +insert into tt6 values(1, 2); +insert into tt6 values(2, 9); +select * from tt5,tt6 where tt5.f1 = tt6.f1 and tt5.f1 = tt5.f2 - tt6.f2; + f1 | f2 | f1 | f2 +----+----+----+---- + 1 | 10 | 1 | 9 +(1 row) + diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql index 9bda6f1d00..70911408d4 100644 --- a/src/test/regress/sql/join.sql +++ b/src/test/regress/sql/join.sql @@ -349,3 +349,19 @@ DROP TABLE t3; DROP TABLE J1_TBL; DROP TABLE J2_TBL; + +-- +-- regression test for problems of the sort depicted in bug #3494 +-- + +create temp table tt5(f1 int, f2 int); +create temp table tt6(f1 int, f2 int); + +insert into tt5 values(1, 10); +insert into tt5 values(1, 11); + +insert into tt6 values(1, 9); +insert into tt6 values(1, 2); +insert into tt6 values(2, 9); + +select * from tt5,tt6 where tt5.f1 = tt6.f1 and tt5.f1 = tt5.f2 - tt6.f2;