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From "Prasad Chakka (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-279) Implement predicate push down for hive queries
Date Sun, 01 Mar 2009 04:06:12 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-279.3.patch

incorporated comments from Namit and added a bunch of new testcases.

due to changes to exprNodeDesc, the outputs of all parse unit tests have changed. I will upload
them in couple of days. otherwise there are no pending code changes for this JIRA.

will open jiras for the following further optimizatons
1) mult-insert
2) intermediate filter operators for partial pushdown
3) remove pushed preds from original operator to eliminate repeat evaluation.
4) merge successive filter ops into single op

> 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
>    Affects Versions: 0.2.0
>            Reporter: Prasad Chakka
>            Assignee: Prasad Chakka
>         Attachments: hive-279.2.patch, hive-279.3.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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