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

Posted to issues@drill.apache.org by "Aman Sinha (JIRA)" <ji...@apache.org> on 2016/07/29 19:14:20 UTC

[jira] [Assigned] (DRILL-4147) Union All operator runs in a single fragment

     [ https://issues.apache.org/jira/browse/DRILL-4147?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Aman Sinha reassigned DRILL-4147:
---------------------------------

    Assignee: Aman Sinha  (was: Sean Hsuan-Yi Chu)

> Union All operator runs in a single fragment
> --------------------------------------------
>
>                 Key: DRILL-4147
>                 URL: https://issues.apache.org/jira/browse/DRILL-4147
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: amit hadke
>            Assignee: Aman Sinha
>
> A User noticed that running select  from a single directory is much faster than union all on two directories.
> (https://drill.apache.org/blog/2014/12/09/running-sql-queries-on-amazon-s3/#comment-2349732267) 
> It seems like UNION ALL operator doesn't parallelize sub scans (its using SINGLETON for distribution type). Everything is ran in single fragment.
> We may have to use SubsetTransformer in UnionAllPrule.



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