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From "Rui Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-16600) Refactor SetSparkReducerParallelism#needSetParallelism to enable parallel order by in multi_insert cases
Date Wed, 10 May 2017 08:48:04 GMT

    [ https://issues.apache.org/jira/browse/HIVE-16600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16004325#comment-16004325
] 

Rui Li commented on HIVE-16600:
-------------------------------

Hi [~kellyzly], please check your patch, seems it doesn't build.
Meanwhile, you have to update {{testconfiguration.properties}} for the test framework to pick
up the new test. Since the test is only intended for spark, you can add it in the {{spark.only.query.files}}
section.
Some comments about the new qtest:
# Why do we need {{cast(key as double) as keyD}}? It's not needed in the target table right?
# The data in the target tables is not ordered. You should add {{-- SORT_QUERY_RESULTS}} to
the test.
# It's quite interesting that we have an extra reduce stage when there's limit in multi insert.
The extra stage only does the limit. And this isn't necessary because we're sorting with only
one reducer. Per my experience, this won't happen with single insert. So please do some investigation
on this. I think the extra stage can be removed, otherwise, there's no point in disabling
parallel order by in this case.

> Refactor SetSparkReducerParallelism#needSetParallelism to enable parallel order by in
multi_insert cases
> --------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-16600
>                 URL: https://issues.apache.org/jira/browse/HIVE-16600
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: liyunzhang_intel
>            Assignee: liyunzhang_intel
>         Attachments: HIVE-16600.1.patch, HIVE-16600.2.patch
>
>
> multi_insert_gby.case.q
> {code}
> set hive.exec.reducers.bytes.per.reducer=256;
> set hive.optimize.sampling.orderby=true;
> drop table if exists e1;
> drop table if exists e2;
> create table e1 (key string, value string);
> create table e2 (key string);
> FROM (select key, cast(key as double) as keyD, value from src order by key) a
> INSERT OVERWRITE TABLE e1
>     SELECT key, value
> INSERT OVERWRITE TABLE e2
>     SELECT key;
> select * from e1;
> select * from e2;
> {code} 
> the parallelism of Sort is 1 even we enable parallel order by("hive.optimize.sampling.orderby"
is set as "true").  This is not reasonable because the parallelism  should be calcuated by
 [Utilities.estimateReducers|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/spark/SetSparkReducerParallelism.java#L170]
> this is because SetSparkReducerParallelism#needSetParallelism returns false when [children
size of RS|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/spark/SetSparkReducerParallelism.java#L207]
is greater than 1.
> in this case, the children size of {{RS[2]}} is two.
> the logical plan of the case
> {code}
>    TS[0]-SEL[1]-RS[2]-SEL[3]-SEL[4]-FS[5]
>                             -SEL[6]-FS[7]
> {code}



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