GitHub user cloud-fan opened a pull request:
https://github.com/apache/spark/pull/16143
[SPARK-18711][SQL] should disable subexpression elimination for
LambdaVariable
## What changes were proposed in this pull request?
This is kind of a long-standing bug, it's hidden until
https://github.com/apache/spark/pull/15780 , which may add `AssertNotNull` on
top of `LambdaVariable` and thus enables subexpression elimination.
However, subexpression elimination will evaluate the common expressions at
the beginning, which is invalid for `LambdaVariable`. `LambdaVariable` usually
represents loop variable, which can't be evaluated ahead of the loop.
This PR skips expressions containing `LambdaVariable` when doing
subexpression elimination.
## How was this patch tested?
updated test in `DatasetAggregatorSuite`
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/cloud-fan/spark aggregator
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16143.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 #16143
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commit 3c1f20dadbce835771f8cd5fd4425ba6c2d8de45
Author: Wenchen Fan <wenc...@databricks.com>
Date: 2016-12-05T09:40:48Z
should disable subexpression elimination for LambdaVariable
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