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Date: Tue, 16 Sep 2014 17:32:34 +0000 (UTC)
From: "Pankit Thapar (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12741860.1410888102000.46227.1410888754831@Atlassian.JIRA>
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Subject: [jira] [Commented] (HIVE-8137) Empty ORC file handling
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    [ https://issues.apache.org/jira/browse/HIVE-8137?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14135778#comment-14135778 ] 

Pankit Thapar commented on HIVE-8137:
-------------------------------------

The issue is hadoop might create a split in case its a CombineInputFormat. Hadoop specifically creates empty splits.

> Empty ORC file handling
> -----------------------
>
>                 Key: HIVE-8137
>                 URL: https://issues.apache.org/jira/browse/HIVE-8137
>             Project: Hive
>          Issue Type: Improvement
>          Components: File Formats
>    Affects Versions: 0.13.1
>            Reporter: Pankit Thapar
>             Fix For: 0.14.0
>
>
> Hive 13 does not handle reading of a zero size Orc File properly. An Orc file is suposed to have a post-script
> which the ReaderIml class tries to read and initialize the footer with it. But in case, the file is empty 
> or is of zero size, then it runs into an IndexOutOfBound Exception because of ReaderImpl trying to read in its constructor.
> Code Snippet : 
> //get length of PostScript
> int psLen = buffer.get(readSize - 1) & 0xff; 
> In the above code, readSize for an empty file is zero.
> I see that ensureOrcFooter() method performs some sanity checks for footer , 
> so, either we can move the above code snippet to ensureOrcFooter() and throw a "Malformed ORC file exception" or we can create a dummy Reader that does not initialize footer and basically has hasNext() set to false so that it returns false on the first call.
> Basically, I would like to know what might be the correct way to handle an empty ORC file in a mapred job?
> Should we neglect it and not throw an exception or we can throw an exeption that the ORC file is malformed.
> Please let me know your thoughts on this.


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