Details
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New Feature
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Status: Closed
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Major
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Resolution: Fixed
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0.6.0
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None
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Reviewed
Description
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.