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https://issues.apache.org/jira/browse/FLINK-11220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16729019#comment-16729019
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Xingcan Cui commented on FLINK-11220:
-------------------------------------
Hi [~sunjincheng121], I'd like to give some explanations about this problem.
Unlike the common join, the time-windowed join will produce a time-ordered
stream, which means the event times of the results are still aligned with the
watermarks. Thus we can directly choose either of the event time fields from
the original streams as the new event time field.
It's quite an interesting problem to deal with the event time field after some
aggregations or joins (e.g., in common join, no event time field can be
preserved). Personally, I suggest keeping the current manner and maybe in the
future, we can extend the time system to support multiple event times and
separated watermarks.
What do you think?
Best, Xingcan
> Can not Select row time field in JOIN query
> -------------------------------------------
>
> Key: FLINK-11220
> URL: https://issues.apache.org/jira/browse/FLINK-11220
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.8.0
> Reporter: sunjincheng
> Priority: Major
>
> SQL:
> {code:java}
> Orders...toTable(tEnv, 'orderId, 'orderTime.rowtime)
> Payment...toTable(tEnv, 'orderId, 'payTime.rowtime)
> SELECT orderTime, o.orderId, payTime
> FROM Orders AS o JOIN Payment AS p
> ON o.orderId = p.orderId AND
> p.payTime BETWEEN orderTime AND orderTime + INTERVAL '1' HOUR
> {code}
> Execption:
> {code:java}
> org.apache.flink.table.api.TableException: Found more than one rowtime field:
> [orderTime, payTime] in the table that should be converted to a DataStream.
> Please select the rowtime field that should be used as event-time timestamp
> for the DataStream by casting all other fields to TIMESTAMP.
> at
> org.apache.flink.table.api.StreamTableEnvironment.translate(StreamTableEnvironment.scala:906)
> {code}
> The reason for the error is that we have 2 time fields `orderTime` and
> `payTime`. I think we do not need throw the exception, and we can remove
> the logic of `plan.process(new OutputRowtimeProcessFunction[A](conversion,
> rowtimeFields.head.getIndex))`, if we want using the timestamp after
> toDataSteram, we should using `assignTimestampsAndWatermarks()`.
> What do you think ? [~twalthr] [~fhueske]
>
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