GitHub user scwf opened a pull request:
https://github.com/apache/spark/pull/5838
[SPARK-7303] [SQL] push down project if possible when the child is sort
Optimize the case of `project(_, sort)` , a example is:
`select key from (select * from testData order by key) t`
before this PR:
```
== Parsed Logical Plan ==
'Project ['key]
'Subquery t
'Sort ['key ASC], true
'Project [*]
'UnresolvedRelation [testData], None
== Analyzed Logical Plan ==
Project [key#0]
Subquery t
Sort [key#0 ASC], true
Project [key#0,value#1]
Subquery testData
LogicalRDD [key#0,value#1], MapPartitionsRDD[1]
== Optimized Logical Plan ==
Project [key#0]
Sort [key#0 ASC], true
LogicalRDD [key#0,value#1], MapPartitionsRDD[1]
== Physical Plan ==
Project [key#0]
Sort [key#0 ASC], true
Exchange (RangePartitioning [key#0 ASC], 5), []
PhysicalRDD [key#0,value#1], MapPartitionsRDD[1]
```
after this PR
```
== Parsed Logical Plan ==
'Project ['key]
'Subquery t
'Sort ['key ASC], true
'Project [*]
'UnresolvedRelation [testData], None
== Analyzed Logical Plan ==
Project [key#0]
Subquery t
Sort [key#0 ASC], true
Project [key#0,value#1]
Subquery testData
LogicalRDD [key#0,value#1], MapPartitionsRDD[1]
== Optimized Logical Plan ==
Sort [key#0 ASC], true
Project [key#0]
LogicalRDD [key#0,value#1], MapPartitionsRDD[1]
== Physical Plan ==
Sort [key#0 ASC], true
Exchange (RangePartitioning [key#0 ASC], 5), []
Project [key#0]
PhysicalRDD [key#0,value#1], MapPartitionsRDD[1]
```
this rule will first do column pruning on the table and then do sorting.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/scwf/spark pruning
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/5838.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 #5838
----
commit b09b89571a75e5dafb6765845c0ba370029d7406
Author: scwf <[email protected]>
Date: 2015-05-01T14:22:35Z
improve column pruning
----
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