From 68fab04f7c2a07c5308e3d2957198ccd7a80ebc5 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 19 Apr 2018 15:49:12 -0400 Subject: [PATCH] Fix incorrect handling of join clauses pushed into parameterized paths. In some cases a clause attached to an outer join can be pushed down into the outer join's RHS even though the clause is not degenerate --- this can happen if we choose to make a parameterized path for the RHS. If the clause ends up attached to a lower outer join, we'd misclassify it as being a "join filter" not a plain "filter" condition at that node, leading to wrong query results. To fix, teach extract_actual_join_clauses to examine each join clause's required_relids, not just its is_pushed_down flag. (The latter now seems vestigial, or at least in need of rethinking, but we won't do anything so invasive as redefining it in a bug-fix patch.) This has been wrong since we introduced parameterized paths in 9.2, though it's evidently hard to hit given the lack of previous reports. The test case used here involves a lateral function call, and I think that a lateral reference may be required to get the planner to select a broken plan; though I wouldn't swear to that. In any case, even if LATERAL is needed to trigger the bug, it still affects all supported branches, so back-patch to all. Per report from Andreas Karlsson. Thanks to Andrew Gierth for preliminary investigation. Discussion: https://postgr.es/m/f8128b11-c5bf-3539-48cd-234178b2314d@proxel.se --- src/backend/optimizer/plan/createplan.c | 3 +++ src/backend/optimizer/util/restrictinfo.c | 11 ++++++++- src/include/optimizer/restrictinfo.h | 1 + src/test/regress/expected/join.out | 27 +++++++++++++++++++++++ src/test/regress/sql/join.sql | 11 +++++++++ 5 files changed, 52 insertions(+), 1 deletion(-) diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index 50b56e111d8..f50fdc2d2a8 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -3685,6 +3685,7 @@ create_nestloop_plan(PlannerInfo *root, if (IS_OUTER_JOIN(best_path->jointype)) { extract_actual_join_clauses(joinrestrictclauses, + best_path->path.parent->relids, &joinclauses, &otherclauses); } else @@ -3798,6 +3799,7 @@ create_mergejoin_plan(PlannerInfo *root, if (IS_OUTER_JOIN(best_path->jpath.jointype)) { extract_actual_join_clauses(joinclauses, + best_path->jpath.path.parent->relids, &joinclauses, &otherclauses); } else @@ -4090,6 +4092,7 @@ create_hashjoin_plan(PlannerInfo *root, if (IS_OUTER_JOIN(best_path->jpath.jointype)) { extract_actual_join_clauses(joinclauses, + best_path->jpath.path.parent->relids, &joinclauses, &otherclauses); } else diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c index ebae0cd8ce0..fd66c1303db 100644 --- a/src/backend/optimizer/util/restrictinfo.c +++ b/src/backend/optimizer/util/restrictinfo.c @@ -379,6 +379,7 @@ extract_actual_clauses(List *restrictinfo_list, */ void extract_actual_join_clauses(List *restrictinfo_list, + Relids joinrelids, List **joinquals, List **otherquals) { @@ -391,7 +392,15 @@ extract_actual_join_clauses(List *restrictinfo_list, { RestrictInfo *rinfo = lfirst_node(RestrictInfo, l); - if (rinfo->is_pushed_down) + /* + * We must check both is_pushed_down and required_relids, since an + * outer-join clause that's been pushed down to some lower join level + * via path parameterization will not be marked is_pushed_down; + * nonetheless, it must be treated as a filter clause not a join + * clause so far as the lower join level is concerned. + */ + if (rinfo->is_pushed_down || + !bms_is_subset(rinfo->required_relids, joinrelids)) { if (!rinfo->pseudoconstant) *otherquals = lappend(*otherquals, rinfo->clause); diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h index b2a69998fd8..d8d2079f0ed 100644 --- a/src/include/optimizer/restrictinfo.h +++ b/src/include/optimizer/restrictinfo.h @@ -36,6 +36,7 @@ extern List *get_actual_clauses(List *restrictinfo_list); extern List *extract_actual_clauses(List *restrictinfo_list, bool pseudoconstant); extern void extract_actual_join_clauses(List *restrictinfo_list, + Relids joinrelids, List **joinquals, List **otherquals); extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel); diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out index 5b6dd399163..1a91e0adafb 100644 --- a/src/test/regress/expected/join.out +++ b/src/test/regress/expected/join.out @@ -3349,6 +3349,33 @@ order by fault; | 123 | 122 (1 row) +explain (costs off) +select * from +(values (1, array[10,20]), (2, array[20,30])) as v1(v1x,v1ys) +left join (values (1, 10), (2, 20)) as v2(v2x,v2y) on v2x = v1x +left join unnest(v1ys) as u1(u1y) on u1y = v2y; + QUERY PLAN +------------------------------------------------------------- + Nested Loop Left Join + -> Values Scan on "*VALUES*" + -> Hash Right Join + Hash Cond: (u1.u1y = "*VALUES*_1".column2) + Filter: ("*VALUES*_1".column1 = "*VALUES*".column1) + -> Function Scan on unnest u1 + -> Hash + -> Values Scan on "*VALUES*_1" +(8 rows) + +select * from +(values (1, array[10,20]), (2, array[20,30])) as v1(v1x,v1ys) +left join (values (1, 10), (2, 20)) as v2(v2x,v2y) on v2x = v1x +left join unnest(v1ys) as u1(u1y) on u1y = v2y; + v1x | v1ys | v2x | v2y | u1y +-----+---------+-----+-----+----- + 1 | {10,20} | 1 | 10 | 10 + 2 | {20,30} | 2 | 20 | 20 +(2 rows) + -- -- test handling of potential equivalence clauses above outer joins -- diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql index 350d44c8c50..be651ec302f 100644 --- a/src/test/regress/sql/join.sql +++ b/src/test/regress/sql/join.sql @@ -1019,6 +1019,17 @@ select * from where fault = 122 order by fault; +explain (costs off) +select * from +(values (1, array[10,20]), (2, array[20,30])) as v1(v1x,v1ys) +left join (values (1, 10), (2, 20)) as v2(v2x,v2y) on v2x = v1x +left join unnest(v1ys) as u1(u1y) on u1y = v2y; + +select * from +(values (1, array[10,20]), (2, array[20,30])) as v1(v1x,v1ys) +left join (values (1, 10), (2, 20)) as v2(v2x,v2y) on v2x = v1x +left join unnest(v1ys) as u1(u1y) on u1y = v2y; + -- -- test handling of potential equivalence clauses above outer joins --