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https://issues.apache.org/jira/browse/HIVE-20504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16606598#comment-16606598
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Ashutosh Chauhan commented on HIVE-20504:
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[~gopalv] What do you think? Currently we try SMBJ then BMJ then BJ. This patch
changes that order to attempt SMBJ then BJ then BMJ since we postulate that BJ
is better than BMJ in most cases.
> Give simple MJ bigger priority than bucketized ones
> ---------------------------------------------------
>
> Key: HIVE-20504
> URL: https://issues.apache.org/jira/browse/HIVE-20504
> Project: Hive
> Issue Type: Improvement
> Components: Statistics
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
> Attachments: HIVE-20504.01.patch, HIVE-20504.01.patch,
> HIVE-20504.01wip01.patch, HIVE-20504.01wip01.patch
>
>
> from the code it seems "standard" mapjoin is one of the last one tried; in
> case the table estimated to be bucketed in to 2 - but it's small ; Hive willl
> do a bucketmapjoin or dphj...even thru a simple mapjoin could have been an
> alternative...
> https://github.com/apache/hive/blob/154ca3e3b5eb78cd49a4b3650c750ca731fba7da/ql/src/java/org/apache/hadoop/hive/ql/optimizer/ConvertJoinMapJoin.java#L157
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