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https://issues.apache.org/jira/browse/HIVE-2340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13556620#comment-13556620
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Yin Huai commented on HIVE-2340:
--------------------------------
The current implementation of the patch of YSmart covers scenarios when a join
or aggregation operator share the same partition keys with its all parents
(join or aggregation operators).
For example, a single MR job will be generated if all operators in the
following plan share the same partition keys.
{code}
JOIN----
\
----JOIN----
/ \
GBY---- \
----JOIN
/
GBY--- -------------/
{code}
Also, it requires that the bottom join or aggregation operators which will be
processed in the same MR job take input tables instead of intermediate tables.
In future, it should be extended to cover scenarios that involve intermediate
tables, that correlated operators share common partition keys (not exactly the
same keys), and that a join or aggregation operator share common keys with some
of its parents.
> 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
>
>
> Before implementing optimizer for JOIN-GBY, try to implement RS-GBY
> optimizer(cluster-by following group-by).
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