question: private boolean isCheckpointExists ( Connection conn , String key ) throws SQLException { PreparedStatement st = null ; ResultSet rs = null ; try { st = conn . prepareStatement ( chkExistsSql ) ; st . setString ( 1 , key ) ; rs = st . executeQuery ( ) ; return rs . next ( ) ; } finally { U . close ( rs , log ) ; U . close ( st , log ) ; } }
target:  Checks specified checkpoint existing.