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https://issues.apache.org/jira/browse/HADOOP-874?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Owen O'Malley resolved HADOOP-874.
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Resolution: Duplicate
The merge has been completely re-written since 0.10. *smile*
> merge code is really slow
> -------------------------
>
> Key: HADOOP-874
> URL: https://issues.apache.org/jira/browse/HADOOP-874
> Project: Hadoop Core
> Issue Type: Bug
> Components: io
> Affects Versions: 0.10.0
> Reporter: Owen O'Malley
> Assignee: Devaraj Das
> Attachments: merge-no-seek.patch
>
>
> I had a case where the map output buffer size (io.sort.mb) was set too low
> and caused a spill and merge. Fixing the configuration caused it to not spill
> until it was finished. With the spill it took 9.5 minutes per a map. Without
> the spill it took 45 seconds. Therefore, I assume it was taking ~9 minutes to
> do the 2 file merge. That is really slow. The input files to the merge were
> two 25 mb sequence files (default codec (java), block compressed)
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