Federated Server List

scripts-available/CDB_FederatedServer.sql

@@ -0,0 +1,70 @@
+
+-- This function is just a placement to store and use the pattern for
+-- foreign server names
+CREATE OR REPLACE FUNCTION @extschema@.__CDB_FS_Name_Pattern()
+RETURNS TEXT
+AS $$
+    SELECT 'cdb_fs_';
+$$
+LANGUAGE SQL IMMUTABLE PARALLEL SAFE;
+
+
+-- Produce a valid DB name for objects created for the user FDW's
+CREATE OR REPLACE FUNCTION @extschema@.__CDB_FS_Object_Name(fdw_input_name NAME)
+RETURNS NAME
+AS $$
+DECLARE
+    object_name text := format('%s%s', @extschema@.__CDB_FS_Name_Pattern(), fdw_input_name);
+BEGIN
+  -- We discard anything that would be truncated
+  IF (char_length(object_name) < 64) THEN
+    RETURN object_name::name;
+  ELSE
+    RAISE EXCEPTION 'Object name is too long to be used as identifier';
+  END IF;
+END
+$$
+LANGUAGE PLPGSQL IMMUTABLE PARALLEL SAFE;
+
+
+
+-- List registered servers
+-- TODO: Decide whether we want to show extra config (extensions, fetch_size, use_remote_estimate)s 
+CREATE OR REPLACE FUNCTION @extschema@.CDB_Federated_Server_List_Servers(fdw_pattern TEXT DEFAULT '%')
+RETURNS TABLE (
+    name        text,
+    driver      text,
+    host        text,
+    port        text,
+    dbname      text,
+    readmode    text,
+    username    text
+)
+AS $$
+DECLARE
+    server_name text := concat(@extschema@.__CDB_FS_Name_Pattern() || fdw_pattern);
+BEGIN
+    RETURN QUERY SELECT 
+        -- Name as shown to the user
+        right(s.srvname, char_length(s.srvname::TEXT) - char_length(@extschema@.__CDB_FS_Name_Pattern()))::TEXT AS "Name",
+
+        -- Which driver are we using (postgres_fdw, odbc_fdw...)
+        f.fdwname::text AS "Driver",
+
+        -- Read 
+        (SELECT option_value FROM pg_options_to_table(s.srvoptions) WHERE option_name LIKE 'host') AS "Host",
+        (SELECT option_value FROM pg_options_to_table(s.srvoptions) WHERE option_name LIKE 'port') AS "Port",
+        (SELECT option_value FROM pg_options_to_table(s.srvoptions) WHERE option_name LIKE 'dbname') AS "DBName",
+        CASE WHEN (SELECT NOT option_value::boolean FROM pg_options_to_table(s.srvoptions) WHERE option_name LIKE 'updatable') THEN 'read-only' ELSE 'read-write' END AS "ReadMode",
+
+        -- Read username from user mappings
+        (SELECT option_value FROM pg_options_to_table(u.umoptions) WHERE option_name LIKE 'user') AS "Username"
+    FROM pg_foreign_server s
+    JOIN pg_foreign_data_wrapper f ON f.oid=s.srvfdw
+    LEFT JOIN pg_user_mappings u
+    ON u.srvid = s.oid
+    WHERE s.srvname ILIKE server_name
+    ORDER BY 1;
+END
+$$
+LANGUAGE PLPGSQL IMMUTABLE PARALLEL SAFE;