[jira] [Commented] (HIVE-279) Implement predicate push down for hive queries

["Lefty Leverenz (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15116932#comment-15116932 ] 

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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)