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https://issues.apache.org/jira/browse/KAFKA-8315?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16845088#comment-16845088
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ASF GitHub Bot commented on KAFKA-8315:
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guozhangwang commented on pull request #6664: KAFKA-8315: fix the JoinWindows
retention deprecation doc
URL: https://github.com/apache/kafka/pull/6664
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> Historical join issues
> ----------------------
>
> Key: KAFKA-8315
> URL: https://issues.apache.org/jira/browse/KAFKA-8315
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: Andrew
> Assignee: John Roesler
> Priority: Major
> Attachments: code.java
>
>
> The problem we are experiencing is that we cannot reliably perform simple
> joins over pre-populated kafka topics. This seems more apparent where one
> topic has records at less frequent record timestamp intervals that the other.
> An example of the issue is provided in this repository :
> [https://github.com/the4thamigo-uk/join-example]
>
> The only way to increase the period of historically joined records is to
> increase the grace period for the join windows, and this has repercussions
> when you extend it to a large period e.g. 2 years of minute-by-minute records.
> Related slack conversations :
> [https://confluentcommunity.slack.com/archives/C48AHTCUQ/p1556799561287300]
> [https://confluentcommunity.slack.com/archives/C48AHTCUQ/p1557733979453900]
>
> Research on this issue has gone through a few phases :
> 1) This issue was initially thought to be due to the inability to set the
> retention period for a join window via {{Materialized: i.e.}}
> The documentation says to use `Materialized` not `JoinWindows.until()`
> ([https://kafka.apache.org/22/javadoc/org/apache/kafka/streams/kstream/JoinWindows.html#until-long-]),
> but there is no where to pass a `Materialized` instance to the join
> operation, only to the group operation is supported it seems.
> This was considered to be a problem with the documentation not with the API
> and is addressed in [https://github.com/apache/kafka/pull/6664]
> 2) We then found an apparent issue in the code which would affect the
> partition that is selected to deliver the next record to the join. This would
> only be a problem for data that is out-of-order, and join-example uses data
> that is in order of timestamp in both topics. So this fix is thought not to
> affect join-example.
> This was considered to be an issue and is being addressed in
> [https://github.com/apache/kafka/pull/6719]
> 3) Further investigation using a crafted unit test seems to show that the
> partition-selection and ordering (PartitionGroup/RecordQueue) seems to work ok
> [https://github.com/the4thamigo-uk/kafka/commit/5121851491f2fd0471d8f3c49940175e23a26f1b]
> 4) the current assumption is that the issue is rooted in the way records are
> consumed from the topics :
> We have tried to set various options to suppress reads form the source topics
> but it doesnt seem to make any difference :
> [https://github.com/the4thamigo-uk/join-example/commit/c674977fd0fdc689152695065d9277abea6bef63]
>
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