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Posted to dev@hive.apache.org by "Suhas Satish (JIRA)" <ji...@apache.org> on 2014/11/02 17:16:33 UTC
[jira] [Commented] (HIVE-8700) Replace ReduceSink to HashTableSink
(or equi.) for small tables [Spark Branch]
[ https://issues.apache.org/jira/browse/HIVE-8700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14193895#comment-14193895 ]
Suhas Satish commented on HIVE-8700:
------------------------------------
Hi Xuefu,
I was working on this as apart of HIVE-8621. Do you want to assign this task to me and swap HIVE-8621 with Szehon instead?
> Replace ReduceSink to HashTableSink (or equi.) for small tables [Spark Branch]
> ------------------------------------------------------------------------------
>
> Key: HIVE-8700
> URL: https://issues.apache.org/jira/browse/HIVE-8700
> Project: Hive
> Issue Type: Sub-task
> Components: Spark
> Reporter: Xuefu Zhang
> Assignee: Szehon Ho
>
> With HIVE-8616 enabled, the new plan has ReduceSinkOperator for the small tables. For example, the follow represents the operator plan for the small table dec1 derived from query {code}explain select /*+ MAPJOIN(dec)*/ * from dec join dec1 on dec.value=dec1.d;{code}
> {code}
> Map 2
> Map Operator Tree:
> TableScan
> alias: dec1
> Statistics: Num rows: 0 Data size: 107 Basic stats: PARTIAL Column stats: NONE
> Filter Operator
> predicate: d is not null (type: boolean)
> Statistics: Num rows: 0 Data size: 0 Basic stats: NONE Column stats: NONE
> Reduce Output Operator
> key expressions: d (type: decimal(5,2))
> sort order: +
> Map-reduce partition columns: d (type: decimal(5,2))
> Statistics: Num rows: 0 Data size: 0 Basic stats: NONE Column stats: NONE
> value expressions: i (type: int)
> {code}
> With the new design for broadcasting small tables, we need to convert the ReduceSinkOperator with HashTableSinkOperator or equivalent in the new plan.
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