GitHub user tejasapatil opened a pull request:
https://github.com/apache/spark/pull/17993
[SPARK-20758][SQL] Add Constant propagation optimization
## What changes were proposed in this pull request?
Added a rule based on this logic:
- look for expression node with an `AND` and none of its children have a
`NOT` or `OR` operation.
- Populate a mapping of attribute => constant value by looking at all the
`EqualTo` predicates
- Using this mapping, replace occurrence of the attributes with the
corresponding constant values in both the children of the `AND` node.
## How was this patch tested?
- Added unit tests
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/tejasapatil/spark
SPARK-20758_const_propagation
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17993.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 #17993
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commit bb3b349d5b895bd8ca5b7db75845dede08601f40
Author: Tejas Patil <tej...@fb.com>
Date: 2017-05-02T15:36:18Z
Initial version of constant propagation
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