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From "Ron Bodkin (JIRA)" <>
Subject [jira] [Commented] (HIVE-2116) Optimize map-side scans for right-side of join
Date Sun, 17 Apr 2011 00:41:05 GMT


Ron Bodkin commented on HIVE-2116:

Table b was an HBase table, rather than a traditional HDFS file, if that is relevant to the

> Optimize map-side scans for right-side of join
> ----------------------------------------------
>                 Key: HIVE-2116
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Ron Bodkin
> I had a large query like select * from a join b on a.key=b.key where...; 
> Table b was too large, so I attempted to optimize by adding constraints on b to the where
clause, e.g.,
> where b.size>=mn and b.size<=mx and ...;
> However, the Hive 0.8.0 optimizer pushed the constraint on b into the reduce phase (defeating
its purpose).
> I was able to force Hive to run the optimization map-side by this workaround:
> join (select * from b where size>=mn and size<=mx) b on a.key=b.key where ...;
> But it would be nice for Hive to pull filters on joined records into the map phase where

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