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https://issues.apache.org/jira/browse/FLINK-7293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16105963#comment-16105963
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Dian Fu commented on FLINK-7293:
--------------------------------
{quote}
Could you explain a bit why this is needed?
{quote}
As we need to support clauses such as
{code}
SELECT *
FROM Ticker MATCH_RECOGNIZE (
PARTITION BY symbol
ORDER BY tstamp, price
MEASURES STRT.tstamp AS start_tstamp,
LAST(DOWN.tstamp) AS bottom_tstamp,
LAST(UP.tstamp) AS end_tstamp
ONE ROW PER MATCH
AFTER MATCH SKIP TO LAST UP
PATTERN (STRT DOWN+ UP+)
DEFINE
DOWN AS DOWN.price < PREV(DOWN.price),
UP AS UP.price > PREV(UP.price)
) MR
{code}
There may be multiple columns to order by.
{quote}
I can't see a way to sort an unbounded stream of data Could you elaborate a
bit how do you see it working?
how this is going to play well with the Time semantics.
When both event-time and a custom order-by is used, who is going to win?
{quote}
This is working in the same way as the implementation of {{sort by}} in table
API. That's to say, both the event-time and the custom order-by will be used
and the event-time should be considered with higher priority and the custom
order-by will be considered with lower priorities. (Please refer to
[DataStreamSort.scala|https://github.com/apache/flink/blob/b8c8f204de718e6d5b7c3df837deafaed7c375f5/flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/datastream/DataStreamSort.scala]
for more details)
Thoughts?
> Support custom order by in PatternStream
> ----------------------------------------
>
> Key: FLINK-7293
> URL: https://issues.apache.org/jira/browse/FLINK-7293
> Project: Flink
> Issue Type: Sub-task
> Components: CEP
> Reporter: Dian Fu
> Assignee: Dian Fu
>
> Currently, when {{ProcessingTime}} is configured, the events are fed to NFA
> in the order of the arriving time and when {{EventTime}} is configured, the
> events are fed to NFA in the order of the event time. It should also allow
> custom {{order by}} to allow users to define the order of the events besides
> the above factors.
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