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From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-352) Make Hive support column based storage
Date Tue, 21 Apr 2009 06:53:48 GMT

    [ https://issues.apache.org/jira/browse/HIVE-352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12701074#action_12701074
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Zheng Shao commented on HIVE-352:
---------------------------------

Yongqiang talked with me offline since 1 conflicts with Joydeep's earlier comment: "We have
seen that having a number of open codecs can hurt in memory usage - that's one open question
for me - can we actually afford to open N concurrent compressed streams (assuming each column
is stored compressed separately)."

I think we should do an experiment to see how much memory each concurrent compressing stream
takes - in reality, most tables will have less than 100 columns, so I guess if each codec
takes 100K-500K memory it's affordable (total memory usage: 10MB-50MB), otherwise we need
to rethink about 1. I 


> Make Hive support column based storage
> --------------------------------------
>
>                 Key: HIVE-352
>                 URL: https://issues.apache.org/jira/browse/HIVE-352
>             Project: Hadoop Hive
>          Issue Type: New Feature
>            Reporter: He Yongqiang
>            Assignee: He Yongqiang
>         Attachments: hive-352-2009-4-15.patch, hive-352-2009-4-16.patch, hive-352-2009-4-17.patch,
hive-352-2009-4-19.patch, HIve-352-draft-2009-03-28.patch, Hive-352-draft-2009-03-30.patch
>
>
> column based storage has been proven a better storage layout for OLAP. 
> Hive does a great job on raw row oriented storage. In this issue, we will enhance hive
to support column based storage. 
> Acctually we have done some work on column based storage on top of hdfs, i think it will
need some review and refactoring to port it to Hive.
> Any thoughts?

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