You are viewing a plain text version of this content. The canonical link for it is here.

Posted to issues@spark.apache.org by "Justin Uang (JIRA)" <ji...@apache.org> on 2016/04/12 14:13:25 UTC

[jira] [Commented] (SPARK-9850) Adaptive execution in Spark

    [ https://issues.apache.org/jira/browse/SPARK-9850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15237056#comment-15237056 ] 

Justin Uang commented on SPARK-9850:
------------------------------------

I like this idea a lot. One thing we encounter in our use cases is that we end up accidentally joining on a field that is 50% nulls, or a string that represents null like "N/A". It then becomes quite cumbersome to have to constantly have to have a Spark expert dig in and find why there is 1 task that will never finish. Would it be possible to add a threshold such that if a join key ever gets too big, it will just fail the job with an error message?

> Adaptive execution in Spark
> ---------------------------
>
>                 Key: SPARK-9850
>                 URL: https://issues.apache.org/jira/browse/SPARK-9850
>             Project: Spark
>          Issue Type: Epic
>          Components: Spark Core, SQL
>            Reporter: Matei Zaharia
>            Assignee: Yin Huai
>         Attachments: AdaptiveExecutionInSpark.pdf
>
>
> Query planning is one of the main factors in high performance, but the current Spark engine requires the execution DAG for a job to be set in advance. Even with cost-based optimization, it is hard to know the behavior of data and user-defined functions well enough to always get great execution plans. This JIRA proposes to add adaptive query execution, so that the engine can change the plan for each query as it sees what data earlier stages produced.
> We propose adding this to Spark SQL / DataFrames first, using a new API in the Spark engine that lets libraries run DAGs adaptively. In future JIRAs, the functionality could be extended to other libraries or the RDD API, but that is more difficult than adding it in SQL.
> I've attached a design doc by Yin Huai and myself explaining how it would work in more detail.



--
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