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Date: Fri, 28 Jul 2017 18:00:06 +0000 (UTC)
From: "Janaki Lahorani (JIRA)" <jira@apache.org>
To: issues@hive.apache.org
Message-ID: <JIRA.13083647.1498784696000.39430.1501264806710@Atlassian.JIRA>
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Subject: [jira] [Commented] (HIVE-16998) Add config to enable HoS DPP only
 for map-joins
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archived-at: Fri, 28 Jul 2017 18:00:11 -0000


    [ https://issues.apache.org/jira/browse/HIVE-16998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16105383#comment-16105383 ] 

Janaki Lahorani commented on HIVE-16998:
----------------------------------------

Resolved merge conflicts with HIVE-17087.  Addressed comments from [~stakiar]

> Add config to enable HoS DPP only for map-joins
> -----------------------------------------------
>
>                 Key: HIVE-16998
>                 URL: https://issues.apache.org/jira/browse/HIVE-16998
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Logical Optimizer, Spark
>            Reporter: Sahil Takiar
>            Assignee: Janaki Lahorani
>         Attachments: HIVE16998.1.patch, HIVE16998.2.patch, HIVE16998.3.patch, HIVE16998.4.patch, HIVE16998.5.patch
>
>
> HoS DPP will split a given operator tree in two under the following conditions: it has detected that the query can benefit from DPP, and the filter is not a map-join (see SplitOpTreeForDPP).
> This can hurt performance if the the non-partitioned side of the join involves a complex operator tree - e.g. the query {{select count(*) from srcpart where srcpart.ds in (select max(srcpart.ds) from srcpart union all select min(srcpart.ds) from srcpart)}} will require running the subquery twice, once in each Spark job.
> Queries with map-joins don't get split into two operator trees and thus don't suffer from this drawback. Thus, it would be nice to have a config key that just enables DPP on HoS for map-joins.


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