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https://issues.apache.org/jira/browse/HIVE-15489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15861978#comment-15861978
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Xuefu Zhang commented on HIVE-15489:
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{quote}
I've thought about this. The downside is many good cases will be turned to
reduce join as well. But I think this config is mainly for stability, so it
should be fine, as long as we document this well. Will add to next patch.
{quote}
My concern is that the map joins down below may also suffer the consequence of
inaccurate stats.
{quote}
Do you think we should combine these two? since they are similar.
{quote}
It's probably better to have two as they control behaviors on different
functionality.
> Alternatively use table scan stats for HoS
> ------------------------------------------
>
> Key: HIVE-15489
> URL: https://issues.apache.org/jira/browse/HIVE-15489
> Project: Hive
> Issue Type: Improvement
> Components: Spark, Statistics
> Affects Versions: 2.2.0
> Reporter: Chao Sun
> Assignee: Chao Sun
> Attachments: HIVE-15489.1.patch, HIVE-15489.2.patch,
> HIVE-15489.3.patch, HIVE-15489.4.patch, HIVE-15489.wip.patch
>
>
> For MapJoin in HoS, we should provide an option to only use stats in the TS
> rather than the populated stats in each of the join branch. This could be
> pretty conservative but more reliable.
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