Check the server is of type PG and return jsonb

scripts-available/CDB_FederatedServerDiagnostics.sql

@@ -1,12 +1,38 @@
+--------------------------------------------------------------------------------
+-- Private functions
+--------------------------------------------------------------------------------
+
+CREATE OR REPLACE FUNCTION @extschema@.__CDB_FS_Server_Diagnostics_PG(server_internal name)
+RETURNS jsonb
+AS $$
+BEGIN
+    RETURN '{}'::jsonb;
+END
+$$
+LANGUAGE PLPGSQL VOLATILE PARALLEL UNSAFE;
+
+
+
 --------------------------------------------------------------------------------
 -- Public functions
 --------------------------------------------------------------------------------
 
+--
+-- TODO: function documentation
+--
 CREATE OR REPLACE FUNCTION @extschema@.CDB_Federated_Server_Diagnostics(server TEXT)
-RETURNS json -- TODO decide if json or jsonb
+RETURNS jsonb
 AS $$
+DECLARE
+    server_internal name := @extschema@.__CDB_FS_Generate_Server_Name(input_name => server, check_existence => true);
+    server_type name := @extschema@.__CDB_FS_server_type(server_internal);
 BEGIN
-    RETURN '{}'::json;
+    CASE server_type
+    WHEN 'postgres_fdw' THEN
+        RETURN @extschema@.__CDB_FS_Server_Diagnostics_PG(server_internal);
+    ELSE
+        RAISE EXCEPTION 'Not implemented server type % for remote server %', server_type, server;
+    END CASE;
 END
 $$
 LANGUAGE PLPGSQL VOLATILE PARALLEL UNSAFE;