LIMIT and ORDER BY in hop window is not supported?

[徐涛]

Hi,
        I want a top n result on each hop window result, but some error throws 
out when I add the order by sentence or the limit sentence, so how do I 
implement such case ?
        Thanks a lot.

SELECT
    trackId as id,track_title as description, count(*) as cnt
FROM
    play
WHERE
    appName='play.statistics.trace'
GROUP BY
    HOP(started_at_ts, INTERVAL '1' SECOND, INTERVAL '5' 
MINUTE),trackId,track_title
ORDER BY
    cnt desc
LIMIT 10

FlinkLogicalSort(sort0=[$2], dir0=[DESC])
  FlinkLogicalWindowAggregate(group=[{1, 2}], cnt=[COUNT()])
    FlinkLogicalCalc(expr#0..4=[{inputs}], 
expr#5=[_UTF-16LE'play.statistics.trace'], expr#6=[=($t0, $t5)], 
started_at_ts=[$t4], trackId=[$t1], track_title=[$t2], $condition=[$t6])
      FlinkLogicalNativeTableScan(table=[[play]])

This exception indicates that the query uses an unsupported SQL feature.
Please check the documentation for the set of currently supported SQL features.
        at 
org.apache.flink.table.api.TableEnvironment.runVolcanoPlanner(TableEnvironment.scala:275)
        at 
org.apache.flink.table.api.StreamTableEnvironment.optimize(StreamTableEnvironment.scala:845)
        at 
org.apache.flink.table.api.StreamTableEnvironment.translate(StreamTableEnvironment.scala:892)
        at 
org.apache.flink.table.api.StreamTableEnvironment.writeToSink(StreamTableEnvironment.scala:344)
        at 
org.apache.flink.table.api.TableEnvironment.insertInto(TableEnvironment.scala:786)
        at 
org.apache.flink.table.api.TableEnvironment.sqlUpdate(TableEnvironment.scala:723)
        at 
org.apache.flink.table.api.TableEnvironment.sqlUpdate(TableEnvironment.scala:683)

Best
Henry