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https://issues.apache.org/jira/browse/HIVE-17308?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16174207#comment-16174207
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Lefty Leverenz commented on HIVE-17308:
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Wow, you're fast!
> Improvement in join cardinality estimation
> ------------------------------------------
>
> Key: HIVE-17308
> URL: https://issues.apache.org/jira/browse/HIVE-17308
> Project: Hive
> Issue Type: Improvement
> Components: Query Planning
> Reporter: Vineet Garg
> Assignee: Vineet Garg
> Fix For: 3.0.0
>
> Attachments: HIVE-17308.1.patch, HIVE-17308.2.patch,
> HIVE-17308.3.patch, HIVE-17308.4.patch, HIVE-17308.5.patch,
> HIVE-17308.6.patch, HIVE-17308.7.patch, HIVE-17308.8.patch
>
>
> Currently during logical planning join cardinality is estimated assuming no
> correlation among join keys (This estimation is done using exponential
> backoff). Physical planning on the other hand consider correlation for multi
> keys and uses different estimation. We should consider correlation during
> logical planning as well.
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