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From "Rajesh Balamohan (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5140) TableInputFormat subclass to allow N number of splits per region during MR jobs
Date Fri, 02 Mar 2012 06:38:59 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5140?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13220725#comment-13220725

Rajesh Balamohan commented on HBASE-5140:

@Josh - Thanks for this patch.

for loop within getSplits() generates the splits with the help of generateRegionSplits().
However, the returned list<InputSplit> is not added back to "List<InputSplit>
splits = new ArrayList<InputSplit>(keys.getFirst().length);"

> TableInputFormat subclass to allow N number of splits per region during MR jobs
> -------------------------------------------------------------------------------
>                 Key: HBASE-5140
>                 URL: https://issues.apache.org/jira/browse/HBASE-5140
>             Project: HBase
>          Issue Type: New Feature
>          Components: mapreduce
>    Affects Versions: 0.90.4
>            Reporter: Josh Wymer
>            Priority: Trivial
>              Labels: mapreduce, split
>             Fix For: 0.90.4
>         Attachments: Added_functionality_to_TableInputFormat_that_allows_splitting_of_regions.patch,
Added_functionality_to_TableInputFormat_that_allows_splitting_of_regions.patch.1, Added_functionality_to_split_n_times_per_region_on_mapreduce_jobs.patch
>   Original Estimate: 72h
>  Remaining Estimate: 72h
> In regards to [HBASE-5138|https://issues.apache.org/jira/browse/HBASE-5138] I am working
on a patch for the TableInputFormat class that overrides getSplits in order to generate N
number of splits per regions and/or N number of splits per job. The idea is to convert the
startKey and endKey for each region from byte[] to BigDecimal, take the difference, divide
by N, convert back to byte[] and generate splits on the resulting values. Assuming your keys
are fully distributed this should generate splits at nearly the same number of rows per split.
Any suggestions on this issue are welcome.

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