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From "Gunther Hagleitner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5834) Avoid reading ORC footers for files which will not be split in OrcInputFormat::getSplits()
Date Fri, 15 Nov 2013 22:43:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5834?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13824197#comment-13824197
] 

Gunther Hagleitner commented on HIVE-5834:
------------------------------------------

Nice find. LGTM.

> Avoid reading ORC footers for files which will not be split in OrcInputFormat::getSplits()
> ------------------------------------------------------------------------------------------
>
>                 Key: HIVE-5834
>                 URL: https://issues.apache.org/jira/browse/HIVE-5834
>             Project: Hive
>          Issue Type: Improvement
>          Components: Tez
>    Affects Versions: tez-branch
>            Reporter: Gopal V
>            Assignee: Gopal V
>              Labels: perfomance, split
>             Fix For: tez-branch
>
>         Attachments: HIVE-5834.00-tez.patch
>
>
> OrcInputFormat::getSplits() fires off a SplitGenerator task for every file in the task.
> The footer & data are on the same node for all files with only 1 hdfs block. On top
of that, it will never need a further split as long as its total size is < context.maxSize.
> Reading that footer locally is faster than reading it in the split gen and sending it
from the AM.



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