[jira] [Commented] (HIVE-2677) Joins involving where statements with a partition do not prune correctly in left outer join

["Dongming Liang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-2677?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14305700#comment-14305700 ] 

Dongming Liang commented on HIVE-2677:
--------------------------------------

I'll work on a push-down pruning for such case.

> Joins involving where statements with a partition do not prune correctly in left outer join
> -------------------------------------------------------------------------------------------
>
>                 Key: HIVE-2677
>                 URL: https://issues.apache.org/jira/browse/HIVE-2677
>             Project: Hive
>          Issue Type: Bug
>          Components: Query Processor
>    Affects Versions: 0.7.0
>            Reporter: Jakob Homan
>              Labels: partition_pruner
>
> The following query:
> {noformat}
> select t1.id as m_id, count(t2.id) as totals 
> from table1 t1 left outer join table2 t2 on (t1.id = t2.id) 
> where (datepartition ==  '2011-11-08-00') 
> group by t1.id;{noformat}
> should prune to just a single partition (datepartition ==  '2011-11-08-00') .  However, the filter is being applied in the reducer, so a full table scan is being done as part of the map.
> One can get the correct behavior by pushing the filter into a select statement within the join itself:
> {noformat}select t1.id as m_id, count(p.id) as totals 
> from table1 t1 left outer join (select * from table2 where datepartition ==  '2011-11-08-00') t2 on (t1.id = t2.id)  
> group by t1.id;{noformat}



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