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From "Peter Davis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (KAFKA-5285) Optimize upper / lower byte range for key range scan on windowed stores
Date Fri, 16 Feb 2018 18:05:00 GMT

    [ https://issues.apache.org/jira/browse/KAFKA-5285?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16367673#comment-16367673

Peter Davis commented on KAFKA-5285:

Thank you Guozhang for looking into this.  Good point Xavier; for my part, the serious issue
was when using `ReadOnlySessionStore.fetch(from,to)` which I believe implies a minSuffix of
0.  Anything would be better than the current behavior of querying the range [keyFrom, infinity],
which loads not just a few extra sessions outside the timestamp range, but *half the entire
database* :-)

> Optimize upper / lower byte range for key range scan on windowed stores
> -----------------------------------------------------------------------
>                 Key: KAFKA-5285
>                 URL: https://issues.apache.org/jira/browse/KAFKA-5285
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>            Reporter: Xavier Léauté
>            Assignee: Guozhang Wang
>            Priority: Major
>              Labels: performance
> The current implementation of {{WindowKeySchema}} / {{SessionKeySchema}} {{upperRange}}
and {{lowerRange}} does not make any assumptions with respect to the other key bound (e.g.
the upper byte bound does not depends on lower key bound).
> It should be possible to optimize the byte range somewhat further using the information
provided by the lower bound.
> More specifically, by incorporating that information, we should be able to eliminate
the corresponding {{upperRangeFixedSize}} and {{lowerRangeFixedSize}}, since the result should
be the same if we implement that optimization.

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