postgreSQL 查询表结构

SELECT DISTINCT C.relname AS tabname,obj_description ( C.oid ) AS COMMENT  FROM (SELECT DISTINCT tablename, schemaname FROM pg_tables WHERE  POSITION ( '_2' IN tablename ) = 0) ts 	
    LEFT JOIN pg_class C ON C.relname = ts.tablename WHERE 	obj_description ( C.oid ) is not  null;