From f3dd9fe1dd9254680591aa8d9891b90b8d735b2a Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 31 Mar 2022 14:29:24 -0400 Subject: Fix postgres_fdw to check shippability of sort clauses properly. postgres_fdw would push ORDER BY clauses to the remote side without verifying that the sort operator is safe to ship. Moreover, it failed to print a suitable USING clause if the sort operator isn't default for the sort expression's type. The net result of this is that the remote sort might not have anywhere near the semantics we expect, which'd be disastrous for locally-performed merge joins in particular. We addressed similar issues in the context of ORDER BY within an aggregate function call in commit 7012b132d, but failed to notice that query-level ORDER BY was broken. Thus, much of the necessary logic already existed, but it requires refactoring to be usable in both cases. Back-patch to all supported branches. In HEAD only, remove the core code's copy of find_em_expr_for_rel, which is no longer used and really should never have been pushed into equivclass.c in the first place. Ronan Dunklau, per report from David Rowley; reviews by David Rowley, Ranier Vilela, and myself Discussion: https://postgr.es/m/CAApHDvr4OeC2DBVY--zVP83-K=bYrTD7F8SZDhN4g+pj2f2S-A@mail.gmail.com --- contrib/postgres_fdw/postgres_fdw.h | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'contrib/postgres_fdw/postgres_fdw.h') diff --git a/contrib/postgres_fdw/postgres_fdw.h b/contrib/postgres_fdw/postgres_fdw.h index 8ae79e97e44..21f2b20ce8d 100644 --- a/contrib/postgres_fdw/postgres_fdw.h +++ b/contrib/postgres_fdw/postgres_fdw.h @@ -173,6 +173,9 @@ extern bool is_foreign_expr(PlannerInfo *root, extern bool is_foreign_param(PlannerInfo *root, RelOptInfo *baserel, Expr *expr); +extern bool is_foreign_pathkey(PlannerInfo *root, + RelOptInfo *baserel, + PathKey *pathkey); extern void deparseInsertSql(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, List *targetAttrs, bool doNothing, @@ -215,10 +218,12 @@ extern void deparseTruncateSql(StringInfo buf, DropBehavior behavior, bool restart_seqs); extern void deparseStringLiteral(StringInfo buf, const char *val); -extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel); -extern Expr *find_em_expr_for_input_target(PlannerInfo *root, - EquivalenceClass *ec, - PathTarget *target); +extern EquivalenceMember *find_em_for_rel(PlannerInfo *root, + EquivalenceClass *ec, + RelOptInfo *rel); +extern EquivalenceMember *find_em_for_rel_target(PlannerInfo *root, + EquivalenceClass *ec, + RelOptInfo *rel); extern List *build_tlist_to_deparse(RelOptInfo *foreignrel); extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel, List *tlist, -- cgit v1.2.3