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From "Enis Soztutar (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-8369) MapReduce over snapshot files
Date Wed, 17 Apr 2013 22:29:15 GMT
Enis Soztutar created HBASE-8369:

             Summary: 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
            Reporter: Enis Soztutar
            Assignee: Enis Soztutar
             Fix For: 0.98.0, 0.95.2

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
 - (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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