v0-0001-Don-t-hash-a-record-array-SAOP-whose-input-type-i.patch

From d81d95a0fc08df30a71a33bcc992066d8f95a1ca Mon Sep 17 00:00:00 2001
From: Andrei Lepikhov <andrei.lepikhov@pgedge.com>
Date: Fri, 5 Jun 2026 07:11:54 +0000
Subject: [PATCH v0 1/3] Don't hash a record/array SAOP whose input type isn't
 hashable

convert_saop_to_hashed_saop_walker() decided to evaluate a
ScalarArrayOpExpr with a hash table whenever get_op_hash_functions()
reported the operator as hashable.  That function only performs a
pg_amop membership test, and since 01e658fa74c added hash/record_ops,
it returns true for record_eq unconditionally.  But record_eq (like
array_eq) is only actually hashable when every column/element type has
a hash function.  For a composite type with a non-hashable column type
(e.g. tsvector) and an array of at least MIN_ARRAY_SIZE_FOR_HASHED_SAOP
constant elements, the planner therefore enabled hashing and the executor
failed at runtime.

This is the same trap that hash_ok_operator() fell into and that
17da9d4c282 fixed for subplan hashing. Give the SAOP planner gate the same
treatment.
---
 src/backend/optimizer/util/clauses.c      | 26 +++++++++++++++++++++--
 src/backend/utils/cache/lsyscache.c       |  6 +++---
 src/test/regress/expected/expressions.out | 25 ++++++++++++++++++++++
 src/test/regress/sql/expressions.sql      | 20 +++++++++++++++++
 4 files changed, 72 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index cd86311bb0b..d44f674dc76 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -2535,6 +2535,24 @@ convert_saop_to_hashed_saop(Node *node)
 	(void) convert_saop_to_hashed_saop_walker(node, NULL);
 }
 
+/*
+ * saop_hashable_for_type
+ *		Can a hashed ScalarArrayOpExpr safely use equality operator 'eqop'
+ *		for left-hand input type 'lefttype'?
+ *
+ * get_op_hash_functions() reports record_eq and array_eq as hashable
+ * unconditionally.  But hashability actually depends on the specific input
+ * type: every column/element type must itself be hashable.  Re-check such
+ * operators through op_hashjoinable().
+ */
+static bool
+saop_hashable_for_type(Oid eqop, Oid lefttype)
+{
+	if (eqop == RECORD_EQ_OP || eqop == ARRAY_EQ_OP)
+		return op_hashjoinable(eqop, lefttype);
+	return true;
+}
+
 static bool
 convert_saop_to_hashed_saop_walker(Node *node, void *context)
 {
@@ -2554,7 +2572,9 @@ convert_saop_to_hashed_saop_walker(Node *node, void *context)
 			if (saop->useOr)
 			{
 				if (get_op_hash_functions(saop->opno, &lefthashfunc, &righthashfunc) &&
-					lefthashfunc == righthashfunc)
+					lefthashfunc == righthashfunc &&
+					saop_hashable_for_type(saop->opno,
+										   exprType(linitial(saop->args))))
 				{
 					Datum		arrdatum = ((Const *) arrayarg)->constvalue;
 					ArrayType  *arr = (ArrayType *) DatumGetPointer(arrdatum);
@@ -2586,7 +2606,9 @@ convert_saop_to_hashed_saop_walker(Node *node, void *context)
 				 */
 				if (OidIsValid(negator) &&
 					get_op_hash_functions(negator, &lefthashfunc, &righthashfunc) &&
-					lefthashfunc == righthashfunc)
+					lefthashfunc == righthashfunc &&
+					saop_hashable_for_type(negator,
+										   exprType(linitial(saop->args))))
 				{
 					Datum		arrdatum = ((Const *) arrayarg)->constvalue;
 					ArrayType  *arr = (ArrayType *) DatumGetPointer(arrdatum);
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 036086057d7..3c7fecf526d 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1659,9 +1659,9 @@ op_mergejoinable(Oid opno, Oid inputtype)
  * Returns true if the operator is hashjoinable.  (There must be a suitable
  * hash opfamily entry for this operator if it is so marked.)
  *
- * In some cases (currently only array_eq), hashjoinability depends on the
- * specific input data type the operator is invoked for, so that must be
- * passed as well.  We currently assume that only one input's type is needed
+ * In some cases (currently array_eq and record_eq), hashjoinability depends
+ * on the specific input data type the operator is invoked for, so that must
+ * be passed as well.  We currently assume that only one input's type is needed
  * to check this --- by convention, pass the left input's data type.
  */
 bool
diff --git a/src/test/regress/expected/expressions.out b/src/test/regress/expected/expressions.out
index 730f7bc7eba..c35583cb2ea 100644
--- a/src/test/regress/expected/expressions.out
+++ b/src/test/regress/expected/expressions.out
@@ -561,3 +561,28 @@ from inttest;
 (3 rows)
 
 rollback;
+--
+-- Hashed SAOP must not be selected for a composite type that is not actually
+-- hashable.
+--
+CREATE TABLE hashed_saop_tbl (a int, b tsvector);
+INSERT INTO hashed_saop_tbl
+  SELECT g, ('w' || g)::tsvector FROM generate_series(1, 1000) g;
+ANALYZE hashed_saop_tbl;
+-- Throws an ERROR if the hashed strategy has been chosen
+EXPLAIN (ANALYZE, COSTS OFF, TIMING OFF, BUFFERS OFF, SUMMARY OFF)
+SELECT count(*) FROM hashed_saop_tbl
+WHERE (a,b) = ANY (ARRAY[
+  (1, 'w1'::tsvector), (2, 'w2'::tsvector), (3, 'w3'::tsvector),
+  (4, 'w4'::tsvector), (5, 'w5'::tsvector), (6, 'w6'::tsvector),
+  (7, 'w7'::tsvector), (8, 'w8'::tsvector), (9, 'w9'::tsvector)
+  ]);
+                                                                               QUERY PLAN                                                                               
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Aggregate (actual rows=1.00 loops=1)
+   ->  Seq Scan on hashed_saop_tbl (actual rows=9.00 loops=1)
+         Filter: (ROW(a, b) = ANY ('{"(1,''w1'')","(2,''w2'')","(3,''w3'')","(4,''w4'')","(5,''w5'')","(6,''w6'')","(7,''w7'')","(8,''w8'')","(9,''w9'')"}'::record[]))
+         Rows Removed by Filter: 991
+(4 rows)
+
+DROP TABLE hashed_saop_tbl;
diff --git a/src/test/regress/sql/expressions.sql b/src/test/regress/sql/expressions.sql
index 3b3048f9731..08691877902 100644
--- a/src/test/regress/sql/expressions.sql
+++ b/src/test/regress/sql/expressions.sql
@@ -301,3 +301,23 @@ select
 from inttest;
 
 rollback;
+
+--
+-- Hashed SAOP must not be selected for a composite type that is not actually
+-- hashable.
+--
+
+CREATE TABLE hashed_saop_tbl (a int, b tsvector);
+INSERT INTO hashed_saop_tbl
+  SELECT g, ('w' || g)::tsvector FROM generate_series(1, 1000) g;
+ANALYZE hashed_saop_tbl;
+
+-- Throws an ERROR if the hashed strategy has been chosen
+EXPLAIN (ANALYZE, COSTS OFF, TIMING OFF, BUFFERS OFF, SUMMARY OFF)
+SELECT count(*) FROM hashed_saop_tbl
+WHERE (a,b) = ANY (ARRAY[
+  (1, 'w1'::tsvector), (2, 'w2'::tsvector), (3, 'w3'::tsvector),
+  (4, 'w4'::tsvector), (5, 'w5'::tsvector), (6, 'w6'::tsvector),
+  (7, 'w7'::tsvector), (8, 'w8'::tsvector), (9, 'w9'::tsvector)
+  ]);
+DROP TABLE hashed_saop_tbl;
-- 
2.54.0