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From "Phabricator (JIRA)" <>
Subject [jira] [Commented] (HIVE-2340) optimize orderby followed by a groupby
Date Wed, 06 Feb 2013 04:03:15 GMT


Phabricator commented on HIVE-2340:

hagleitn has commented on the revision "HIVE-2340 [jira] optimize orderby followed by a groupby".

  ql/src/java/org/apache/hadoop/hive/ql/optimizer/ HashSet?
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/ 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/ 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?


To: JIRA, navis
Cc: hagleitn, njain

> optimize orderby followed by a groupby
> --------------------------------------
>                 Key: HIVE-2340
>                 URL:
>             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.D1209.5.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,
> Before implementing optimizer for JOIN-GBY, try to implement RS-GBY optimizer(cluster-by
following group-by).

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