You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@spark.apache.org by "Apache Spark (Jira)" <ji...@apache.org> on 2020/07/17 05:57:00 UTC
[jira] [Commented] (SPARK-29343) Eliminate sorts without limit in
the subquery of Join/Aggregation
[ https://issues.apache.org/jira/browse/SPARK-29343?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17159693#comment-17159693 ]
Apache Spark commented on SPARK-29343:
--------------------------------------
User 'ulysses-you' has created a pull request for this issue:
https://github.com/apache/spark/pull/29142
> Eliminate sorts without limit in the subquery of Join/Aggregation
> -----------------------------------------------------------------
>
> Key: SPARK-29343
> URL: https://issues.apache.org/jira/browse/SPARK-29343
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: EdisonWang
> Assignee: EdisonWang
> Priority: Major
> Fix For: 3.0.0
>
>
> The {{Sort}} without {{Limit}} operator in {{Join/GroupBy}} subquery is useless.
>
> For example, {{select count(1) from (select a from test1 order by a)}} is equal to {{select count(1) from (select a from test1)}}.
> 'select * from (select a from test1 order by a) t1 join (select b from test2) t2 on t1.a = t2.b' is equal to {{select * from (select a from test1) t1 join (select b from test2) t2 on t1.a = t2.b}}.
> Remove useless {{Sort}} operator can import performance.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org