GitHub user JoshRosen opened a pull request:
https://github.com/apache/spark/pull/7807
[SPARK-9489] Remove unnecessary compatibility and requirements checks from
Exchange
While reviewing @yhuai's patch for SPARK-2205 (#7773), I noticed that
Exchange's `compatible` check may be incorrectly returning `false` in many
cases. As far as I know, this is not actually a problem because the
`compatible`, `meetsRequirements`, and `needsAnySort` checks are serving only
as short-circuit performance optimizations that are not necessary for
correctness.
In order to reduce code complexity, I think that we should remove these
checks and unconditionally rewrite the operator's children. This should be
safe because we rewrite the tree in a single bottom-up pass.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/JoshRosen/spark SPARK-9489
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/7807.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 #7807
----
commit 9d76ce9953c88c457fe41da24805a60c659f8ded
Author: Josh Rosen <[email protected]>
Date: 2015-07-30T22:19:16Z
[SPARK-9489] Remove compatibleWith, meetsRequirements, and needsAnySort
checks from Exchange
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