Disallow triggers on CAggs

We don't support triggers on CAggs yet. Disallow that explicitly
till we support them later.

Fixes #6500

.unreleased/fix_6522

@@ -0,0 +1,2 @@
+Fixes: #6522 Disallow triggers on CAggs
+Thanks: @HollowMan6 Thanks for reporting this issue

src/process_utility.c

@@ -3851,12 +3851,19 @@ process_create_trigger_start(ProcessUtilityArgs *args)
 	Cache *hcache;
 	Hypertable *ht;
 	ObjectAddress PG_USED_FOR_ASSERTS_ONLY address;
+	Oid relid = RangeVarGetRelid(stmt->relation, NoLock, true);
 
 	hcache = ts_hypertable_cache_pin();
-	ht = ts_hypertable_cache_get_entry_rv(hcache, stmt->relation);
+	ht = ts_hypertable_cache_get_entry(hcache, relid, CACHE_FLAG_MISSING_OK);
 	if (ht == NULL)
 	{
 		ts_cache_release(hcache);
+		/* check if it's a cagg. We don't support triggers on them yet */
+		if (ts_continuous_agg_find_by_relid(relid) != NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("triggers are not supported on continuous aggregate")));
+
 		return DDL_CONTINUE;
 	}
 

tsl/test/expected/cagg_errors.out

@@ -321,6 +321,14 @@ INNER JOIN _timescaledb_catalog.hypertable h ON(h.id = ca.mat_hypertable_id)
 WHERE user_view_name = 'mat_with_test'
 \gset
 \set ON_ERROR_STOP 0
+-- triggers not allowed on  continuous aggregate
+CREATE OR REPLACE FUNCTION not_allowed() RETURNS trigger AS $$
+BEGIN
+  RETURN NEW;
+END; $$ LANGUAGE plpgsql;
+CREATE TRIGGER not_allowed_trigger INSTEAD OF INSERT ON mat_with_test
+FOR EACH ROW EXECUTE FUNCTION not_allowed();
+ERROR:  triggers are not supported on continuous aggregate
 ALTER MATERIALIZED VIEW mat_with_test SET(timescaledb.create_group_indexes = 'false');
 ERROR:  cannot alter create_group_indexes option for continuous aggregates
 ALTER MATERIALIZED VIEW mat_with_test SET(timescaledb.create_group_indexes = 'true');

tsl/test/sql/cagg_errors.sql

@@ -290,6 +290,15 @@ WHERE user_view_name = 'mat_with_test'
 \gset
 
 \set ON_ERROR_STOP 0
+-- triggers not allowed on  continuous aggregate
+CREATE OR REPLACE FUNCTION not_allowed() RETURNS trigger AS $$
+BEGIN
+  RETURN NEW;
+END; $$ LANGUAGE plpgsql;
+
+CREATE TRIGGER not_allowed_trigger INSTEAD OF INSERT ON mat_with_test
+FOR EACH ROW EXECUTE FUNCTION not_allowed();
+
 ALTER MATERIALIZED VIEW mat_with_test SET(timescaledb.create_group_indexes = 'false');
 ALTER MATERIALIZED VIEW mat_with_test SET(timescaledb.create_group_indexes = 'true');
 ALTER MATERIALIZED VIEW mat_with_test ALTER timec DROP default;