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https://issues.apache.org/jira/browse/HIVE-1015?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12796812#action_12796812
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Todd Lipcon commented on HIVE-1015:
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I think it's very slightly different:
- UDF - only a 1:1 mapping on a single column
- UDAF - requires implementation of Combiner-like functionality, best I can
tell (haven't delved into this deeply, so apologies if you can do a
reducer-only UDAF)
- UDTF - perhaps supports the same functionality, but the syntax is a little
less obvious than the MAP/REDUCE syntax. I think this feature could be
implemented by an AST transform and some kind of interface-changing wrapper
class for UDTF that makes it look more like the usual MR API.
BTW, these thoughts definitely shouldn't block progress on this JIRA. I just
wanted to throw the idea out there.
> Java MapReduce wrapper for TRANSFORM/MAP/REDUCE scripts
> -------------------------------------------------------
>
> Key: HIVE-1015
> URL: https://issues.apache.org/jira/browse/HIVE-1015
> Project: Hadoop Hive
> Issue Type: Improvement
> Components: Contrib
> Reporter: Carl Steinbach
> Attachments: HIVE-1015.patch
>
>
> Larry Ogrodnek has written a set of wrapper classes that make it possible
> to write Hive TRANSFORM/MAP/REDUCE scripts in Java in a style that
> more closely resembles conventional Hadoop MR programs.
> A blog post describing this library can be found here:
> http://dev.bizo.com/2009/10/hive-map-reduce-in-java.html
> The source code (with Apache license) is available here:
> http://github.com/ogrodnek/shmrj
> We should add this to contrib.
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