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https://issues.apache.org/jira/browse/HIVE-2340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13572126#comment-13572126
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Phabricator commented on HIVE-2340:
-----------------------------------
hagleitn has commented on the revision "HIVE-2340 [jira] optimize orderby
followed by a groupby".
INLINE COMMENTS
ql/src/java/org/apache/hadoop/hive/ql/optimizer/ReduceSinkDeDuplication.java:138
HashSet?
ql/src/java/org/apache/hadoop/hive/ql/optimizer/ReduceSinkDeDuplication.java:251
I think the "number of reducers" story deserves more comments (similar to what
you've explained on the jira)
ql/src/java/org/apache/hadoop/hive/ql/optimizer/ReduceSinkDeDuplication.java:787
I think if you just run this optimization *after* CommonJoinResolver
everything should be fine. It will either already have converted joins to
mapjoins and this optimization won't apply or you still have a regular join and
you can merge it without worrying about missing out on a mapjoin conversion.
You could still have the "sorted" flag to express intent, but there isn't any
optimization that will pull the rug out under you at the moment. Am I missing
something?
REVISION DETAIL
https://reviews.facebook.net/D1209
To: JIRA, navis
Cc: hagleitn, njain
> optimize orderby followed by a groupby
> --------------------------------------
>
> Key: HIVE-2340
> URL: https://issues.apache.org/jira/browse/HIVE-2340
> Project: Hive
> Issue Type: Sub-task
> Components: Query Processor
> Reporter: Navis
> Assignee: Navis
> Priority: Minor
> Labels: perfomance
> Attachments: ASF.LICENSE.NOT.GRANTED--HIVE-2340.D1209.1.patch,
> ASF.LICENSE.NOT.GRANTED--HIVE-2340.D1209.2.patch,
> ASF.LICENSE.NOT.GRANTED--HIVE-2340.D1209.3.patch,
> ASF.LICENSE.NOT.GRANTED--HIVE-2340.D1209.4.patch,
> ASF.LICENSE.NOT.GRANTED--HIVE-2340.D1209.5.patch, HIVE-2340.1.patch.txt,
> HIVE-2340.D1209.10.patch, HIVE-2340.D1209.6.patch, HIVE-2340.D1209.7.patch,
> HIVE-2340.D1209.8.patch, HIVE-2340.D1209.9.patch, testclidriver.txt
>
>
> Before implementing optimizer for JOIN-GBY, try to implement RS-GBY
> optimizer(cluster-by following group-by).
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