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From "Prasad Chakka (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-279) Implement predicate push down for hive queries
Date Fri, 27 Mar 2009 18:36:50 GMT

     [ https://issues.apache.org/jira/browse/HIVE-279?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Prasad Chakka updated HIVE-279:
-------------------------------

    Attachment: hive-279.4.patch

updated the patch to the latest trunk

> Implement predicate push down for hive queries
> ----------------------------------------------
>
>                 Key: HIVE-279
>                 URL: https://issues.apache.org/jira/browse/HIVE-279
>             Project: Hadoop Hive
>          Issue Type: New Feature
>          Components: Query Processor
>    Affects Versions: 0.2.0
>            Reporter: Prasad Chakka
>            Assignee: Prasad Chakka
>         Attachments: hive-279.2.patch, hive-279.3.patch, hive-279.4.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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