Stub remote server latency (WIP)

scripts-available/CDB_FederatedServerDiagnostics.sql

@@ -97,6 +97,18 @@ AS $$
 $$
 LANGUAGE SQL VOLATILE PARALLEL UNSAFE;
 
+--
+-- Get the network latency to a remote PG server
+--
+CREATE OR REPLACE FUNCTION @extschema@.__CDB_FS_Foreign_Server_Latency_PG(server_internal name)
+RETURNS float
+AS $$
+BEGIN
+    RETURN 0.0;
+END
+$$
+LANGUAGE PLPGSQL VOLATILE PARALLEL UNSAFE;
+
 
 --
 -- Collect and return diagnostics info from a remote PG into a jsonb
@@ -108,11 +120,13 @@ DECLARE
     remote_server_version  text := @extschema@.__CDB_FS_Foreign_Server_Version_PG(server_internal);
     remote_postgis_version text := @extschema@.__CDB_FS_Foreign_PostGIS_Version_PG(server_internal);
     remote_server_options jsonb := @extschema@.__CDB_FS_Foreign_Server_Options_PG(server_internal);
+    remote_server_latency float := @extschema@.__CDB_FS_Foreign_Server_Latency_PG(server_internal);
 BEGIN
     RETURN jsonb_build_object(
         'server_version', remote_server_version,
         'postgis_version', remote_postgis_version,
-        'server_options', remote_server_options
+        'server_options', remote_server_options,
+        'server_latency', remote_server_latency
     );
 END
 $$

test/CDB_FederatedServerDiagnostics.sql

@@ -57,6 +57,9 @@ SELECT '1.5', cartodb.CDB_Federated_Server_Diagnostics(server => 'loopback') @>
 \echo '%% It returns the remote server options'
 SELECT '1.6', cartodb.CDB_Federated_Server_Diagnostics(server => 'loopback') @> '{"server_options": {"host": "localhost", "port": "@@PGPORT@@", "updatable": "false", "extensions": "postgis", "fetch_size": "1000", "use_remote_estimate": "true"}}'::jsonb;
 
+\echo '%% It returns the network latency to the remote server'
+SELECT '1.7', cartodb.CDB_Federated_Server_Diagnostics(server => 'loopback') @> '{"server_latency": 0.0}'::jsonb;
+
 
 -- ===================================================================
 -- Cleanup