Handle when FROM clause is missing in continuous aggregate definition

It now errors out for such a case.

Fixes #5500

CHANGELOG.md

@@ -28,6 +28,7 @@ accidentally triggering the load of a previous DB version.**
 * #5459 Fix issue creating dimensional constraints
 * #5499 Do not segfault on large histogram() parameters
 * #5497 Allow named time_bucket arguments in Cagg definition
+* #5500 Fix when no FROM clause in continuous aggregate definition
 
 **Thanks**
 * @nikolaps for reporting an issue with the COPY fetcher

tsl/src/continuous_aggs/create.c

@@ -1050,7 +1050,11 @@ cagg_query_supported(const Query *query, StringInfo hint, StringInfo detail, con
 	}
 #endif
 #endif
-
+	if (!query->jointree->fromlist)
+	{
+		appendStringInfoString(hint, "FROM clause missing in the query");
+		return false;
+	}
 	if (query->commandType != CMD_SELECT)
 	{
 		appendStringInfoString(hint, "Use a SELECT query in the continuous aggregate view.");

tsl/test/expected/cagg_errors.out

@@ -631,3 +631,6 @@ ERROR:  invalid continuous aggregate query
 CREATE MATERIALIZED VIEW matv1 AS SELECT now() AS time;
 CREATE MATERIALIZED VIEW cagg1 WITH (timescaledb.continuous) AS SELECT time_bucket('1h',time) FROM matv1 GROUP BY 1;
 ERROR:  invalid continuous aggregate view
+-- No FROM clause in CAGG definition
+CREATE MATERIALIZED VIEW cagg1 with (timescaledb.continuous) AS SELECT 1 GROUP BY 1 WITH NO DATA;
+ERROR:  invalid continuous aggregate query

tsl/test/sql/cagg_errors.sql

@@ -523,3 +523,5 @@ CREATE MATERIALIZED VIEW cagg1 WITH (timescaledb.continuous) AS SELECT time_buck
 CREATE MATERIALIZED VIEW matv1 AS SELECT now() AS time;
 CREATE MATERIALIZED VIEW cagg1 WITH (timescaledb.continuous) AS SELECT time_bucket('1h',time) FROM matv1 GROUP BY 1;
 
+-- No FROM clause in CAGG definition
+CREATE MATERIALIZED VIEW cagg1 with (timescaledb.continuous) AS SELECT 1 GROUP BY 1 WITH NO DATA;