[jira] [Assigned] (SPARK-8964) Use Exchange in limit operations (per partition limit -> exchange to one partition -> per partition limit)

["Apache Spark (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-8964?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-8964:
-----------------------------------

    Assignee: Apache Spark  (was: Josh Rosen)

> Use Exchange in limit operations (per partition limit -> exchange to one partition -> per partition limit)
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: SPARK-8964
>                 URL: https://issues.apache.org/jira/browse/SPARK-8964
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Josh Rosen
>            Assignee: Apache Spark
>
> Spark SQL's physical Limit operator currently performs its own shuffle rather than using Exchange to perform the shuffling.  This is less efficient since this non-exchange shuffle path won't be able to benefit from SQL-specific shuffling optimizations, such as SQLSerializer2.  It also involves additional unnecessary row copying.
> Instead, I think that we should rewrite Limit to expand into three physical operators:
> PerParititonLimit -> Exchange to one partition -> PerPartitionLimit



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org