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https://issues.apache.org/jira/browse/HIVE-279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15116932#comment-15116932
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Lefty Leverenz commented on HIVE-279:
-------------------------------------
Doc note: This added *hive.optimize.ppd* with a default value of false in
0.4.0. The default was changed to true in 0.4.0 by HIVE-626.
* [Configuration Properties -- hive.optimize.ppd |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.optimize.ppd]
> Implement predicate push down for hive queries
> ----------------------------------------------
>
> Key: HIVE-279
> URL: https://issues.apache.org/jira/browse/HIVE-279
> Project: Hive
> Issue Type: New Feature
> Components: Query Processor
> Affects Versions: 0.6.0
> Reporter: Prasad Chakka
> Assignee: Prasad Chakka
> Fix For: 0.4.0
>
> Attachments: hive-279.2.patch, hive-279.3.patch, hive-279.4.patch,
> hive-279.5.patch, hive-279.6.patch, hive-279.patch
>
>
> Push predicates that are expressed in outer queries into inner queries where
> possible so that rows will get filtered out sooner.
> eg.
> select a.*, b.* from a join b on (a.uid = b.uid) where a.age = 20 and
> a.gender = 'm'
> current compiler generates the filter predicate in the reducer after the join
> so all the rows have to be passed from mapper to reducer. by pushing the
> filter predicate to the mapper, query performance should improve.
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