Hi Henry, Currently, Order By is supported in Streaming&Batch while Limit is only supported in Batch. Another thing to be noted is, for Order by, the result of streaming queries must be primarily sorted on an ascending time attribute[1].
[1] https://ci.apache.org/projects/flink/flink-docs-master/dev/table/sql.html#orderby--limit On Thu, Sep 27, 2018 at 9:05 PM 徐涛 <happydexu...@gmail.com> wrote: > 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 >
