GitHub user ericl opened a pull request:
https://github.com/apache/spark/pull/13161
[SPARK-14851] Support radix sort with nullable longs
## What changes were proposed in this pull request?
This adds support for radix sort of nullable long fields. When a sort field
is null and radix sort is enabled, we keep nulls in a separate region of the
sort buffer so that radix sort does not need to deal with them. This also has
performance benefits when sorting smaller integer types, since two's complement
nulls otherwise force a full-width radix sort.
This strategy for nulls does mean the sort is no longer stable. cc @davies
## How was this patch tested?
Existing randomized sort tests for correctness. I also tested some TPCDS
queries and there does not seem to be any significant regression for non-null
sorts.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ericl/spark sc-2998
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/13161.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #13161
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commit 7d29dc35488aa51f297bea64de1a36dd4ac7ed98
Author: Eric Liang <e...@databricks.com>
Date: 2016-05-18T02:06:51Z
Tue May 17 19:06:51 PDT 2016
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