GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/spark/pull/12719
[SPARK-14939][SQL] Eliminate No-op Alias SortOrder in Sort.
## What changes were proposed in this pull request?
This issue aims to delete No-op **Alias** SortOrders in Sort. Currently,
`EliminateSorts` removes direct foldable expressions, but cannot handle aliases.
**Before**
```
scala> sql("select a, year(current_date()) as y from (select
explode(array(1,2)) a) order by y").explain()
== Physical Plan ==
WholeStageCodegen
: +- Sort [y#8 ASC], true, 0
: +- INPUT
+- Exchange rangepartitioning(y#8 ASC, 200), None
+- WholeStageCodegen
: +- Project [a#13,2016 AS y#8]
: +- INPUT
+- Generate explode([1,2]), false, false, [a#13]
+- Scan OneRowRelation[]
```
**After**
```
scala> sql("select a, year(current_date()) as y from (select
explode(array(1,2)) a) order by y").explain()
== Physical Plan ==
WholeStageCodegen
: +- Project [a#13,2016 AS y#8]
: +- INPUT
+- Generate explode([1,2]), false, false, [a#13]
+- Scan OneRowRelation[]
```
## How was this patch tested?
Pass the Jenkins tests including a new test case.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/spark SPARK-14939
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/12719.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 #12719
----
commit 9b987848e399ea9c16da196ccdb91bde04066cf4
Author: Dongjoon Hyun <[email protected]>
Date: 2016-04-26T22:27:17Z
[SPARK-XXX][SQL] Eliminate No-op Alias SortOrder in Sort.
----
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