The order_clause specifies the ordering of the data within each partition. If the analytic function contains an order_clause but not a window_frame_clause, the default window_frame_clause is RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW. If the analytic function does not contain an order_clause, Exasol does not sort the data within each partition. Without sorted data, the use of some analytic functions can cause non-deterministic results.