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From "Gaurav Jain (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-1411) [Zebra] Can Zebra use HAR to reduce file/block count for namenode
Date Tue, 11 May 2010 00:41:33 GMT

    [ https://issues.apache.org/jira/browse/PIG-1411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12866003#action_12866003

Gaurav Jain commented on PIG-1411:

We ran few performance tests and found that:

-- Zebra Table with 700 file and 70G of data in them
-- Ceated a HAR file for the above table with 36 files of ~2GB


10-15 seconds overhead in creating split per HAR file

50% increase in SLOT_MILLI_MAPS b/w HAR and Non-HAR reading of Zebra Table. HAR taking more

Similar results were observed for union of above tables ( 5 tables union )

Further performance tests are subject to fix for MAPREDUCE-1712

> [Zebra] Can Zebra use HAR to reduce file/block count for namenode
> -----------------------------------------------------------------
>                 Key: PIG-1411
>                 URL: https://issues.apache.org/jira/browse/PIG-1411
>             Project: Pig
>          Issue Type: New Feature
>          Components: impl
>    Affects Versions: 0.8.0
>            Reporter: Gaurav Jain
>            Assignee: Gaurav Jain
>            Priority: Minor
>             Fix For: 0.8.0
> Due to column group structure,  Zebra can create extra files for namenode to remember.
That means namenode taking more memory for Zebra related files.
> The goal is to reduce the no of files/blocks
> The idea among various options is to use HAR ( Hadoop Archive ). Hadoop Archive reduces
the block  and file count by copying data from small files ( 1M, 2M ...) into a hdfs-block
of larger size. Thus, reducing the total no. of blocks and files.

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