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https://issues.apache.org/jira/browse/HIVE-279?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Prasad Chakka updated HIVE-279:
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Attachment: hive-279.2.patch
Here is an updated patch that simplifies some of the column reference
conversions. Now every operator converts the column references in the predicate
expressions so that they will be understood by the parent operator(s)
> 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.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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