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Posted to issues@hive.apache.org by "Lefty Leverenz (JIRA)" <ji...@apache.org> on 2017/08/03 05:20:00 UTC
[jira] [Commented] (HIVE-16998) Add config to enable HoS DPP only
for map-joins
[ https://issues.apache.org/jira/browse/HIVE-16998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16112207#comment-16112207 ]
Lefty Leverenz commented on HIVE-16998:
---------------------------------------
[~stakiar], please set the fix version for this jira to 3.0.0. Thanks.
> 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
> Labels: TODOC3.0
> 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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