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https://issues.apache.org/jira/browse/FLINK-11220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16729631#comment-16729631
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Xingcan Cui commented on FLINK-11220:
-------------------------------------
Hi [~sunjincheng121] and [~jark], I admit that automatically materializing the
rowtime fields will be convenient in some cases. However, that seems not to be
quite reasonable. Here are my thoughts.
1. As you said, the {{RowtimeIndicator}} and {{TIMESTAMP}} are two different
types. It will be confusing if we implicitly change the field types after a
join.
2. The current approach makes it possible for the time-windowed join to be used
as a sub-query for further rowtime-based operations (e.g., group windows).
3. Now that the results of time-windowed joins are still aligned with
watermarks (which are held-back according to the window size), I think it
doesn't make sense to ignore it and let users assign rowtime/watermarks
manually again.
All in all, using {{CAST}} seems to be a little verbose, but should be a
feasible solution for the time being.
Any idea?
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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