Make constraint rename issue relcache invalidation on target relation

When a constraint gets renamed, it may have associated with it a target
relation (for example domain constraints don't have one).  Not
invalidating the target relation cache when issuing the renaming can
result in issues with subsequent commands that refer to the old
constraint name using the relation cache, causing various failures.  One
pattern spotted was using CREATE TABLE LIKE after a constraint
renaming.

Reported-by: Stuart <sfbarbee@gmail.com>
Author: Amit Langote
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/2047094.V130LYfLq4@station53.ousa.org

src/backend/commands/tablecmds.c

@@ -3026,8 +3026,15 @@ rename_constraint_internal(Oid myrelid,
 	ReleaseSysCache(tuple);
 
 	if (targetrelation)
+	{
 		relation_close(targetrelation, NoLock); /* close rel but keep lock */
 
+		/*
+		 * Invalidate relcache so as others can see the new constraint name.
+		 */
+		CacheInvalidateRelcache(targetrelation);
+	}
+
 	return address;
 }
 

src/test/regress/expected/alter_table.out

@@ -399,6 +399,28 @@ ALTER TABLE IF EXISTS constraint_not_exist RENAME CONSTRAINT con3 TO con3foo; --
 NOTICE:  relation "constraint_not_exist" does not exist, skipping
 ALTER TABLE IF EXISTS constraint_rename_test ADD CONSTRAINT con4 UNIQUE (a);
 NOTICE:  relation "constraint_rename_test" does not exist, skipping
+-- renaming constraints with cache reset of target relation
+CREATE TABLE constraint_rename_cache (a int,
+  CONSTRAINT chk_a CHECK (a > 0),
+  PRIMARY KEY (a));
+ALTER TABLE constraint_rename_cache
+  RENAME CONSTRAINT chk_a TO chk_a_new;
+ALTER TABLE constraint_rename_cache
+  RENAME CONSTRAINT constraint_rename_cache_pkey TO chk_a_gt_zero;
+CREATE TABLE like_constraint_rename_cache
+  (LIKE constraint_rename_cache INCLUDING ALL);
+\d like_constraint_rename_cache
+    Table "public.like_constraint_rename_cache"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           | not null | 
+Indexes:
+    "like_constraint_rename_cache_pkey" PRIMARY KEY, btree (a)
+Check constraints:
+    "chk_a_new" CHECK (a > 0)
+
+DROP TABLE constraint_rename_cache;
+DROP TABLE like_constraint_rename_cache;
 -- FOREIGN KEY CONSTRAINT adding TEST
 CREATE TABLE attmp2 (a int primary key);
 CREATE TABLE attmp3 (a int, b int);

src/test/regress/sql/alter_table.sql

@@ -301,6 +301,20 @@ DROP TABLE constraint_rename_test;
 ALTER TABLE IF EXISTS constraint_not_exist RENAME CONSTRAINT con3 TO con3foo; -- ok
 ALTER TABLE IF EXISTS constraint_rename_test ADD CONSTRAINT con4 UNIQUE (a);
 
+-- renaming constraints with cache reset of target relation
+CREATE TABLE constraint_rename_cache (a int,
+  CONSTRAINT chk_a CHECK (a > 0),
+  PRIMARY KEY (a));
+ALTER TABLE constraint_rename_cache
+  RENAME CONSTRAINT chk_a TO chk_a_new;
+ALTER TABLE constraint_rename_cache
+  RENAME CONSTRAINT constraint_rename_cache_pkey TO chk_a_gt_zero;
+CREATE TABLE like_constraint_rename_cache
+  (LIKE constraint_rename_cache INCLUDING ALL);
+\d like_constraint_rename_cache
+DROP TABLE constraint_rename_cache;
+DROP TABLE like_constraint_rename_cache;
+
 -- FOREIGN KEY CONSTRAINT adding TEST
 
 CREATE TABLE attmp2 (a int primary key);