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https://issues.apache.org/jira/browse/HIVE-6643?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14051220#comment-14051220
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Lefty Leverenz commented on HIVE-6643:
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*hive.exec.check.crossproducts* is documented in the wiki here:
* [Configuration Properties -- hive.exec.check.crossproducts |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.exec.check.crossproducts]
I added a comment to HIVE-6586 so it won't get lost in the shuffle when
HIVE-6037 changes HiveConf.java.
> Add a check for cross products in plans and output a warning
> ------------------------------------------------------------
>
> Key: HIVE-6643
> URL: https://issues.apache.org/jira/browse/HIVE-6643
> Project: Hive
> Issue Type: Bug
> Reporter: Harish Butani
> Assignee: Harish Butani
> Fix For: 0.13.0
>
> Attachments: HIVE-6643.1.patch, HIVE-6643.2.patch, HIVE-6643.3.patch,
> HIVE-6643.4.patch, HIVE-6643.5.patch, HIVE-6643.6.patch, HIVE-6643.7.patch
>
>
> Now that we support old style join syntax, it is easy to write queries that
> generate a plan with a cross product.
> For e.g. say you have A join B join C join D on A.x = B.x and A.y = D.y and
> C.z = D.z
> So the JoinTree is:
> A — B
> |__ D — C
> Since we don't reorder join graphs, we will end up with a cross product
> between (A join B) and C
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