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From "Kevin Wilfong (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-3874) Create a new Optimized Row Columnar file format for Hive
Date Fri, 01 Feb 2013 23:26:15 GMT

    [ https://issues.apache.org/jira/browse/HIVE-3874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13569237#comment-13569237
] 

Kevin Wilfong commented on HIVE-3874:
-------------------------------------

@Owen: Regarding some of the issues I've seen:
1) In the add method in DynamicByteArray, the line which updates remaining seems a little
off, and it causes a NPE if newLength > chunkSize / 2
I think it should be remaining -= size
2) I had trouble reading a column of only null values, I saw division by zero exceptions in
a couple methods of DynamicByteArray.
I wrote up a possible fix here https://reviews.facebook.net/D8361 but I'm not sure if it's
the right fix.

If you want to wait, I can file formal JIRAs for these later instead.
                
> Create a new Optimized Row Columnar file format for Hive
> --------------------------------------------------------
>
>                 Key: HIVE-3874
>                 URL: https://issues.apache.org/jira/browse/HIVE-3874
>             Project: Hive
>          Issue Type: Improvement
>          Components: Serializers/Deserializers
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>         Attachments: hive.3874.2.patch, OrcFileIntro.pptx, orc.tgz
>
>
> There are several limitations of the current RC File format that I'd like to address
by creating a new format:
> * each column value is stored as a binary blob, which means:
> ** the entire column value must be read, decompressed, and deserialized
> ** the file format can't use smarter type-specific compression
> ** push down filters can't be evaluated
> * the start of each row group needs to be found by scanning
> * user metadata can only be added to the file when the file is created
> * the file doesn't store the number of rows per a file or row group
> * there is no mechanism for seeking to a particular row number, which is required for
external indexes.
> * there is no mechanism for storing light weight indexes within the file to enable push-down
filters to skip entire row groups.
> * the type of the rows aren't stored in the file

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