[jira] [Commented] (HIVE-4078) Delay the serialize-deserialize pair in CommonJoinResolver

["Gopal V (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-4078?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13595266#comment-13595266 ] 

Gopal V commented on HIVE-4078:
-------------------------------

Opening review once the patch adding AbstractJoinTaskDispatcher.java enters svn.
                
> Delay the serialize-deserialize pair in CommonJoinResolver
> ----------------------------------------------------------
>
>                 Key: HIVE-4078
>                 URL: https://issues.apache.org/jira/browse/HIVE-4078
>             Project: Hive
>          Issue Type: Bug
>          Components: Query Processor
>            Reporter: Gopal V
>            Assignee: Gopal V
>         Attachments: HIVE-4078-20130305.2.patch, HIVE-4078-20130305.patch, HIVE-4078-20130406.patch
>
>
> CommonJoinProcessor tries to clone a MapredWork while attempting a conversion to a map-join
> {code}
>   // deep copy a new mapred work from xml
>   InputStream in = new ByteArrayInputStream(xml.getBytes("UTF-8"));
>   MapredWork newWork = Utilities.deserializeMapRedWork(in, physicalContext.getConf());
> {code}
> which is a very heavy operation memory wise & cpu-wise.
> It would be better to do this only if a conditional task is required, resulting in a copy of the task.

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