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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-5834) Avoid reading ORC footers for files which will not be split in OrcInputFormat::getSplits()
Date Fri, 15 Nov 2013 22:15:21 GMT

     [ https://issues.apache.org/jira/browse/HIVE-5834?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gopal V updated HIVE-5834:
--------------------------

    Attachment: HIVE-5834.00-tez.patch

Tested with a count(1) with a filter 

For a table of 1500 x 70mb ORC files.

Before = 26 seconds
After  = 18 seconds

For a table of 23699 x ~2mb ORC files

Before = 32.9 seconds
After = 23.0 seconds

> 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: 0.13.0
>            Reporter: Gopal V
>            Assignee: Gopal V
>         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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