Improve FK trigger parallel-safety check added by 05c8482f7f.

Commit 05c8482f7f added special logic related to parallel-safety of FK
triggers. This is a bit of a hack and should have instead been done by
simply setting appropriate proparallel values on those trigger functions
themselves.

Suggested-by: Tom Lane
Author: Greg Nancarrow
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/2309260.1615485644@sss.pgh.pa.us

src/backend/optimizer/util/clauses.c

@@ -971,24 +971,10 @@ target_rel_trigger_max_parallel_hazard(Relation rel,
 	 */
 	for (i = 0; i < rel->trigdesc->numtriggers; i++)
 	{
-		int			trigtype;
 		Oid			tgfoid = rel->trigdesc->triggers[i].tgfoid;
 
 		if (max_parallel_hazard_test(func_parallel(tgfoid), context))
 			return true;
-
-		/*
-		 * If the trigger type is RI_TRIGGER_FK, this indicates a FK exists in
-		 * the relation, and this would result in creation of new CommandIds
-		 * on insert/update and this isn't supported in a parallel worker (but
-		 * is safe in the parallel leader).
-		 */
-		trigtype = RI_FKey_trigger_type(tgfoid);
-		if (trigtype == RI_TRIGGER_FK)
-		{
-			if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
-				return true;
-		}
 	}
 
 	return false;

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202103093
+#define CATALOG_VERSION_NO	202103131
 
 #endif

src/include/catalog/pg_proc.dat

@@ -3745,11 +3745,11 @@
 
 # Generic referential integrity constraint triggers
 { oid => '1644', descr => 'referential integrity FOREIGN KEY ... REFERENCES',
-  proname => 'RI_FKey_check_ins', provolatile => 'v', prorettype => 'trigger',
-  proargtypes => '', prosrc => 'RI_FKey_check_ins' },
+  proname => 'RI_FKey_check_ins', provolatile => 'v', proparallel => 'r',
+  prorettype => 'trigger', proargtypes => '', prosrc => 'RI_FKey_check_ins' },
 { oid => '1645', descr => 'referential integrity FOREIGN KEY ... REFERENCES',
-  proname => 'RI_FKey_check_upd', provolatile => 'v', prorettype => 'trigger',
-  proargtypes => '', prosrc => 'RI_FKey_check_upd' },
+  proname => 'RI_FKey_check_upd', provolatile => 'v', proparallel => 'r',
+  prorettype => 'trigger', proargtypes => '', prosrc => 'RI_FKey_check_upd' },
 { oid => '1646', descr => 'referential integrity ON DELETE CASCADE',
   proname => 'RI_FKey_cascade_del', provolatile => 'v', prorettype => 'trigger',
   proargtypes => '', prosrc => 'RI_FKey_cascade_del' },