Add dummy CDB_Overviews SQL function for tests

test/support/sql/CDB_Overviews.sql

@@ -0,0 +1,15 @@
+-- Mockup for CDB_Overviews
+CREATE OR REPLACE FUNCTION CDB_Overviews(table_name text)
+RETURNS TABLE(z integer, overview_table text)
+AS $$
+  BEGIN
+    IF table_name = 'test_table_overviews' THEN
+      RETURN QUERY
+        SELECT 1 AS z, 'test_table_overviews_ov1'::text AS overviw_table
+        UNION ALL
+        SELECT 2 AS z, 'test_table_overviews_ov2'::text AS overviw_table;
+    ELSE
+      RETURN;
+    END IF;
+  END
+$$ LANGUAGE PLPGSQL;