Handle non existing ht in cache_inval_entry_init

When the continuous_agg_invalidation trigger is called with an invalid
hypertable id (e.g., caused by an inconsistent backup restore), the
hypertable lookup returns NULL. This case was not handled properly so
far. This patch adds proper checks to the function.

(cherry picked from commit 7dc14ac)

tsl/src/continuous_aggs/insert.c

@@ -155,6 +155,13 @@ cache_inval_entry_init(ContinuousAggsCacheInvalEntry *cache_entry, int32 hyperta
 	/* NOTE: we can remove the id=>relid scan, if it becomes an issue, by getting the
 	 * hypertable_relid directly from the Chunk*/
 	Hypertable *ht = ts_hypertable_cache_get_entry_by_id(ht_cache, hypertable_id);
+	if (ht == NULL)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("unable to determine relid for hypertable %d", hypertable_id)));
+	}
+
 	cache_entry->hypertable_id = hypertable_id;
 	cache_entry->entry_id = entry_id;
 	cache_entry->hypertable_relid = ht->main_table_relid;

tsl/test/expected/cagg_usage.out

@@ -412,6 +412,20 @@ DROP TABLE whatever;
 -- Check that continuous_agg_invalidation_trigger() handles no arguments properly
 SELECT _timescaledb_functions.continuous_agg_invalidation_trigger();
 ERROR:  must supply hypertable id
+-- Check that continuous_agg_invalidation_trigger() not crashes when an invalid ht id is used
+CREATE TABLE sensor_data (
+time timestamptz NOT NULL,
+sensor_id integer NOT NULL,
+cpu double precision NULL,
+temperature double precision NULL);
+SELECT FROM create_hypertable('sensor_data','time');
+--
+(1 row)
+
+CREATE TRIGGER ts_cagg_invalidation_trigger AFTER INSERT OR DELETE OR UPDATE ON sensor_data FOR EACH ROW EXECUTE FUNCTION _timescaledb_functions.continuous_agg_invalidation_trigger(999999);
+INSERT INTO sensor_data values('1980-01-01 00:00:00-00', 1, 1, 1);
+ERROR:  unable to determine relid for hypertable 999999
+DROP TABLE sensor_data;
 -- END OF BASIC USAGE TESTS --
 CREATE TABLE metrics(time timestamptz, device TEXT, value float);
 SELECT table_name FROM create_hypertable('metrics','time');

tsl/test/sql/cagg_usage.sql

@@ -270,6 +270,18 @@ DROP TABLE whatever;
 -- Check that continuous_agg_invalidation_trigger() handles no arguments properly
 SELECT _timescaledb_functions.continuous_agg_invalidation_trigger();
 
+-- Check that continuous_agg_invalidation_trigger() not crashes when an invalid ht id is used
+CREATE TABLE sensor_data (
+time timestamptz NOT NULL,
+sensor_id integer NOT NULL,
+cpu double precision NULL,
+temperature double precision NULL);
+
+SELECT FROM create_hypertable('sensor_data','time');
+CREATE TRIGGER ts_cagg_invalidation_trigger AFTER INSERT OR DELETE OR UPDATE ON sensor_data FOR EACH ROW EXECUTE FUNCTION _timescaledb_functions.continuous_agg_invalidation_trigger(999999);
+INSERT INTO sensor_data values('1980-01-01 00:00:00-00', 1, 1, 1);
+DROP TABLE sensor_data;
+
 -- END OF BASIC USAGE TESTS --
 
 CREATE TABLE metrics(time timestamptz, device TEXT, value float);