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]
```
with this rule we will first do column pruning on the table and then do sorting.
Author: scwf <wangfei1@huawei.com>
This patch had conflicts when merged, resolved by
Committer: Michael Armbrust <michael@databricks.com>
Closes#5838 from scwf/pruning and squashes the following commits:
b00d833 [scwf] address michael's comment
e230155 [scwf] fix tests failure
b09b895 [scwf] improve column pruning
59250fe514