GitHub user viirya opened a pull request:
https://github.com/apache/spark/pull/12956
[SPARK-15180][SQL] Support subexpression elimination in Fliter
## What changes were proposed in this pull request?
This patch tries to add the support of subexpression elimination in
wholestage codegen `Fliter`.
Because the predicate expressions are evaluated in `Filter` with an
optimized ordering that reduces unnecessary evaluation as much as possible, we
follow this ordering when doing subexpression elimination too.
Due to that, we can't just extract all common subexpressions and evaluate
them first. Instead, we extract common subexpressions but don't evaluate them.
We evaluate common subexpressions only when the predicate expressions
containing them are evaluated.
## How was this patch tested?
Existing tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/viirya/spark-1 subexpr-filter
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/12956.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 #12956
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commit 55e43ef9f25c68d0c3773f36156b34d42a9baedc
Author: Liang-Chi Hsieh <sim...@tw.ibm.com>
Date: 2016-05-06T14:22:49Z
Support subexpression elimination in Fliter.
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