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authorTom Lane <tgl@sss.pgh.pa.us>2013-11-15 16:46:21 -0500
committerTom Lane <tgl@sss.pgh.pa.us>2013-11-15 16:46:21 -0500
commit1c0dfaa68fa491f2ec4c6f7905246ef07e504d4c (patch)
tree42c41ff3ae615b29378866b71d316c696a290ce0 /src/include
parent8674f1fba90df84910aca5cdc04b8bb19602755b (diff)
downloadpostgresql-1c0dfaa68fa491f2ec4c6f7905246ef07e504d4c.tar.gz
postgresql-1c0dfaa68fa491f2ec4c6f7905246ef07e504d4c.zip
Compute correct em_nullable_relids in get_eclass_for_sort_expr().
Bug #8591 from Claudio Freire demonstrates that get_eclass_for_sort_expr must be able to compute valid em_nullable_relids for any new equivalence class members it creates. I'd worried about this in the commit message for db9f0e1d9a4a0842c814a464cdc9758c3f20b96c, but claimed that it wasn't a problem because multi-member ECs should already exist when it runs. That is transparently wrong, though, because this function is also called by initialize_mergeclause_eclasses, which runs during deconstruct_jointree. The example given in the bug report (which the new regression test item is based upon) fails because the COALESCE() expression is first seen by initialize_mergeclause_eclasses rather than process_equivalence. Fixing this requires passing the appropriate nullable_relids set to get_eclass_for_sort_expr, and it requires new code to compute that set for top-level expressions such as ORDER BY, GROUP BY, etc. We store the top-level nullable_relids in a new field in PlannerInfo to avoid computing it many times. In the back branches, I've added the new field at the end of the struct to minimize ABI breakage for planner plugins. There doesn't seem to be a good alternative to changing get_eclass_for_sort_expr's API signature, though. There probably aren't any third-party extensions calling that function directly; moreover, if there are, they probably need to think about what to pass for nullable_relids anyway. Back-patch to 9.2, like the previous patch in this area.
Diffstat (limited to 'src/include')
-rw-r--r--src/include/nodes/relation.h6
-rw-r--r--src/include/optimizer/paths.h1
2 files changed, 6 insertions, 1 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index a2853fbf044..57083d3ec94 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -150,7 +150,8 @@ typedef struct PlannerInfo
/*
* all_baserels is a Relids set of all base relids (but not "other"
* relids) in the query; that is, the Relids identifier of the final join
- * we need to form.
+ * we need to form. This is computed in make_one_rel, just before we
+ * start making Paths.
*/
Relids all_baserels;
@@ -243,6 +244,9 @@ typedef struct PlannerInfo
/* optional private data for join_search_hook, e.g., GEQO */
void *join_search_private;
+
+ /* This will be in a saner place in 9.4: */
+ Relids nullable_baserels;
} PlannerInfo;
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 9ef93c70c64..96ffdb195fe 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -109,6 +109,7 @@ extern Expr *canonicalize_ec_expression(Expr *expr,
extern void reconsider_outer_join_clauses(PlannerInfo *root);
extern EquivalenceClass *get_eclass_for_sort_expr(PlannerInfo *root,
Expr *expr,
+ Relids nullable_relids,
List *opfamilies,
Oid opcintype,
Oid collation,