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From "Bryan Keller (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-8369) MapReduce over snapshot files
Date Mon, 01 Jul 2013 21:25:28 GMT

     [ https://issues.apache.org/jira/browse/HBASE-8369?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Bryan Keller updated HBASE-8369:
--------------------------------

               Labels: newbie  (was: )
    Affects Version/s: 0.94.8
         Release Note: Snapshot map-reduce scan functionality for 0.94. This is new functionality
only and should not affect other
               Status: Patch Available  (was: Open)

This patch is based on Enis's patch and backported to 0.94. I added a couple of things, like
factoring in data locality when assigning splits, and making the temp directory a parameter.
The big downside so far to these patches is that the map-reduce job needs to be run by a user
that has write access to files in the HBase data directory.
                
> MapReduce over snapshot files
> -----------------------------
>
>                 Key: HBASE-8369
>                 URL: https://issues.apache.org/jira/browse/HBASE-8369
>             Project: HBase
>          Issue Type: New Feature
>          Components: mapreduce, snapshots
>    Affects Versions: 0.94.8
>            Reporter: Enis Soztutar
>            Assignee: Enis Soztutar
>              Labels: newbie
>             Fix For: 0.98.0, 0.95.2
>
>         Attachments: HBASE-8369-0.94.patch, hbase-8369_v0.patch
>
>
> The idea is to add an InputFormat, which can run the mapreduce job over snapshot files
directly bypassing hbase server layer. The IF is similar in usage to TableInputFormat, taking
a Scan object from the user, but instead of running from an online table, it runs from a table
snapshot. We do one split per region in the snapshot, and open an HRegion inside the RecordReader.
A RegionScanner is used internally for doing the scan without any HRegionServer bits. 
> Users have been asking and searching for ways to run MR jobs by reading directly from
hfiles, so this allows new use cases if reading from stale data is ok:
>  - Take snapshots periodically, and run MR jobs only on snapshots.
>  - Export snapshots to remote hdfs cluster, run the MR jobs at that cluster without HBase
cluster.
>  - (Future use case) Combine snapshot data with online hbase data: Scan from yesterday's
snapshot, but read today's data from online hbase cluster. 

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