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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8369) MapReduce over snapshot files
Date Fri, 13 Dec 2013 00:44:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13846981#comment-13846981
] 

Andrew Purtell commented on HBASE-8369:
---------------------------------------

bq. Like an appropriate HRegion constructor, etc.

Something like that could go into 0.96 surely. [~stack] ?

bq. We are going to have to start to go down the Facebook path of forking HBase for things
like this then and our contribution will become less useful over time. So be it.

To put this politely (I have strong opinions) the FB fork was a matter of a tight internal
deployment schedule as opposed to any unwillingness of the community to work with their contributions.


The addition of a couple of extra classes to a private build does not make a fork, just like
the enhancements to reduce byte copies for "smart clients" that Jesse was working that went
mainly into Phoenix didn't produce a fork. If and when the time comes that truly an incompatible
change must be introduced that constitutes a real break, we should definitely look hard at
that.


> 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
>
>         Attachments: HBASE-8369-0.94.patch, HBASE-8369-0.94_v2.patch, HBASE-8369-0.94_v3.patch,
HBASE-8369-0.94_v4.patch, HBASE-8369-0.94_v5.patch, HBASE-8369-trunk_v1.patch, HBASE-8369-trunk_v2.patch,
HBASE-8369-trunk_v3.patch, hbase-8369_v0.patch, hbase-8369_v11.patch, hbase-8369_v5.patch,
hbase-8369_v6.patch, hbase-8369_v7.patch, hbase-8369_v8.patch, hbase-8369_v9.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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