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Posted to issues@flink.apache.org by "Aljoscha Krettek (JIRA)" <ji...@apache.org> on 2016/02/29 20:39:18 UTC
[jira] [Resolved] (FLINK-3538) DataStream join API does not enforce
consistent usage
[ https://issues.apache.org/jira/browse/FLINK-3538?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Aljoscha Krettek resolved FLINK-3538.
-------------------------------------
Resolution: Fixed
Fix Version/s: 1.0.0
Fixed in https://github.com/apache/flink/commit/0ac2b1a7b4b44d0e5722532958e5bda00615dbb4
> DataStream join API does not enforce consistent usage
> -----------------------------------------------------
>
> Key: FLINK-3538
> URL: https://issues.apache.org/jira/browse/FLINK-3538
> Project: Flink
> Issue Type: Improvement
> Components: DataStream API, Scala API
> Affects Versions: 1.0.0
> Reporter: Till Rohrmann
> Assignee: Aljoscha Krettek
> Fix For: 1.0.0
>
>
> In the Scala DataStream API the {{join}} operation does not enforce that the user has specified a {{KeySelector}} for both input sides before applying a window function. Moreover, the order of the {{where}} and {{equalTo}} clause is not fixed and it is possible to specify multiple {{where}} and {{equalTo}} clauses. In the latter case, it is not clear which {{KeySelector}} will eventually be used by the system.
> So the following Flink programs compile without a compilation problem (the first two lines will only fail at runtime):
> {code}
> inputA.join(inputB).equalTo{x => x}.window(TumblingProcessingTimeWindows.of(Time.seconds(10)))
> .apply(new DefaultFlatJoinFunction[String, String]()).print()
> inputA.join(inputB).where{x => x}.window(TumblingProcessingTimeWindows.of(Time.seconds(10)))
> .apply(new DefaultFlatJoinFunction[String, String]()).print()
> inputA.join(inputB).equalTo{x => x}.where{x => x}.where{x => "1"}.equalTo{x => "42"}.window(TumblingProcessingTimeWindows.of(Time.seconds(10)))
> .apply(new DefaultFlatJoinFunction[String, String]()).print()
> {code}
> This is unlike the Java DataStream API where a clear pattern of {{join}} then {{where}} and then {{equalTo}} is enforced. I would propose to do the same for the Scala API.
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