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https://issues.apache.org/jira/browse/CRUNCH-246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13732031#comment-13732031
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Ryan Brush commented on CRUNCH-246:
-----------------------------------
I actually wrote an HFileInputFormat for a specific internal need some time ago
that I'd be happy to contribute to this (it's actually quite simple). However,
I think HBase intentionally doesn't include an HFileInputFormat since it would
be prone to error, some of which is discussed at [1]. In short, the input
wouldn't include data sitting in HBase's write ahead log -- and therefore
logically written to HBase -- but not yet flushed to an HFile. There are ways
you can work around this if you really know what you're doing...but it might be
worth debating whether something like that makes sense in a public API. FWIW,
the HBase community seems to have decided this isn't a good thing to expose
broadly.
I recall some discussion of HBase snapshotting opening the door to running
MapReduce jobs directly against HFiles in a predictable way, but unfortunately
I can't find a reference to that. If and when that becomes available it would
make complete sense to expose in Crunch (and I'm sure some folks here at Cerner
would be happy to contribute to that as well).
[1]
http://mail-archives.apache.org/mod_mbox/hbase-user/201202.mbox/%3C-684097822435171056@unknownmsgid%3E
> HFileSource
> -----------
>
> Key: CRUNCH-246
> URL: https://issues.apache.org/jira/browse/CRUNCH-246
> Project: Crunch
> Issue Type: Improvement
> Components: IO
> Reporter: Chao Shi
> Assignee: Chao Shi
>
> I found this useful when directly perform MR on HFiles. I used it yesterday
> when copying a bunch of HFiles to another cluster (where the region layout is
> different).
> There is no HFileInputFormat provided by HBase, but I found the following
> from google:
> https://gist.github.com/leifwickland/1120311
> http://blog.csdn.net/kirayuan/article/details/7794402 (Java version of the
> above. The webpage is in chinese, but you can see the code)
> I'm not sure if we copy their code directly (copyright issue?). Anyone knows?
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