Fix possible loss of sync between rectypeid and underlying PLpgSQL_type.

tglsfdc · tglsfdc · commit 4ba4bfaf256c · 2019-12-26T15:19:39.000-05:00
When revalidate_rectypeid() acts to update a stale record type OID in plpgsql's data structures, it fixes the active PLpgSQL_rec struct as well as the PLpgSQL_type struct it references. However, the latter is shared across function executions while the former is not. In a later function execution, the PLpgSQL_rec struct would be reinitialized by copy_plpgsql_datums and would then contain a stale type OID, typically leading to "could not open relation with OID NNNN" errors. revalidate_rectypeid() can easily fix this, fortunately, just by treating typ->typoid as authoritative. Per report and diagnosis from Ashutosh Sharma, though this is not his suggested fix. Back-patch to v11 where this code came in. Discussion: https://postgr.es/m/CAE9k0Pkd4dZwt9J5pS9xhJFWpUtqs05C9xk_GEwPzYdV=GxwWg@mail.gmail.com
diff --git a/src/pl/plpgsql/src/expected/plpgsql_record.out b/src/pl/plpgsql/src/expected/plpgsql_record.out
@@ -476,6 +476,12 @@ select sillyaddtwo(42);
           44
 (1 row)
 
+select sillyaddtwo(43);
+ sillyaddtwo 
+-------------
+          45
+(1 row)
+
 -- check access to system columns in a record variable
 create function sillytrig() returns trigger language plpgsql as
 $$begin
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
@@ -6858,7 +6858,16 @@ revalidate_rectypeid(PLpgSQL_rec *rec)
 	Assert(typ != NULL);
 	if (typ->tcache &&
 		typ->tcache->tupDesc_identifier == typ->tupdesc_id)
-		return;					/* known up-to-date */
+	{
+		/*
+		 * Although *typ is known up-to-date, it's possible that rectypeid
+		 * isn't, because *rec is cloned during each function startup from a
+		 * copy that we don't have a good way to update.  Hence, forcibly fix
+		 * rectypeid before returning.
+		 */
+		rec->rectypeid = typ->typoid;
+		return;
+	}
 
 	/*
 	 * typcache entry has suffered invalidation, so re-look-up the type name
diff --git a/src/pl/plpgsql/src/sql/plpgsql_record.sql b/src/pl/plpgsql/src/sql/plpgsql_record.sql
@@ -303,6 +303,7 @@ drop table mutable2;
 select sillyaddtwo(42);  -- fail
 create table mutable2(f0 text, f1 int, f2 text);
 select sillyaddtwo(42);
+select sillyaddtwo(43);
 
 -- check access to system columns in a record variable
 
