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https://issues.apache.org/jira/browse/KAFKA-13216?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guozhang Wang resolved KAFKA-13216.
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Resolution: Fixed
> Streams left/outer joins cause new internal changelog topic to grow unbounded
> -----------------------------------------------------------------------------
>
> Key: KAFKA-13216
> URL: https://issues.apache.org/jira/browse/KAFKA-13216
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: Sergio Peña
> Assignee: Guozhang Wang
> Priority: Critical
> Fix For: 3.1.0
>
>
> This bug is caused by the improvements made in
> https://issues.apache.org/jira/browse/KAFKA-10847, which fixes an issue with
> stream-stream left/outer joins. The issue is only caused when a stream-stream
> left/outer join is used with the new `JoinWindows.ofTimeDifferenceAndGrace()`
> API that specifies the window time + grace period. This new API was added in
> AK 3.0. No previous users are affected.
> The issue causes that the internal changelog topic used by the new
> OUTERSHARED window store keeps growing unbounded as new records come. The
> topic is never cleaned up nor compacted even if tombstones are written to
> delete the joined and/or expired records from the window store. The problem
> is caused by a parameter required in the window store to retain duplicates.
> This config causes that tombstones records have a new sequence ID as part of
> the key ID in the changelog making those keys unique. Thus causing the
> cleanup policy not working.
> In 3.0, we deprecated {{JoinWindows.of(size)}} in favor of
> {{JoinWindows.ofTimeDifferenceAndGrace()}} -- the old API uses the old
> semantics and is thus not affected while the new API enable the new
> semantics; the problem is that we deprecated the old API and thus tell users
> that they should switch to the new broken API.
> We have two ways forward:
> * Fix the bug (non trivial)
> * Un-deprecate the old {{JoinWindow.of(size)}} API (and tell users not to
> use the new but broken API)
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