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From Stephen Sprague <sprag...@gmail.com>
Subject Re: single output file per partition?
Date Wed, 21 Aug 2013 15:51:16 GMT
hi igor,
lots of ideas there!  I can't speak for them all but let me confirm first
that "cluster by X into 1 bucket" didn't work?  I would have thought that
would have done it.




On Tue, Aug 20, 2013 at 2:29 PM, Igor Tatarinov <igor@decide.com> wrote:

> What's the best way to enforce a single output file per partition?
>
> INSERT OVERWRITE TABLE <table>
> PARTITION (x,y,z)
> SELECT ...
> FROM ...
> WHERE ...
>
> It tried adding CLUSTER BY x,y,z at the end thinking that sorting will
> force a single reducer per partition but that didn't work. I still got
> multiple files per partition.
>
> Do I have to use a single reduce task? With a few TB of data that's
> probably not a good idea.
>
> My current idea is to create a temp table with the same partitioning
> structure. Insert into that table first and then select * from that table
> into the output table. With combineinputformat=true that should work right?
>
> Or should I make Hive merge output files instead? (using hive.merge.mapfiles)
> Will that work with a partitioned table?
>
> Thanks!
> igor
>

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