Implement predicate push down for hive queries
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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
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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