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From "Phabricator (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-3874) Create a new Optimized Row Columnar file format for Hive
Date Thu, 21 Feb 2013 10:22:17 GMT

    [ https://issues.apache.org/jira/browse/HIVE-3874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13583078#comment-13583078
] 

Phabricator commented on HIVE-3874:
-----------------------------------

njain has commented on the revision "HIVE-3874 [jira] Create a new Optimized Row Columnar
file format for Hive".


  1. Can you add more comments - specially, in the class/interface definitions
     Writer/TreeWriter/StreamFactory to name a few.
  2. Can column statistics be made optional ? (can be a follow-up)
  3. This has a lot of new code - I mean, is it possible to use some of the constructs which
are
      already there - for eg. RedBlackTrees, RLE etc. Can you use some existing implementations
      instead of writing these from scratch ?

REVISION DETAIL
  https://reviews.facebook.net/D8529

To: JIRA, omalley
Cc: kevinwilfong, njain

                
> 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, HIVE-3874.D8529.1.patch, HIVE-3874.D8529.2.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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