GitHub user gatorsmile opened a pull request:
https://github.com/apache/spark/pull/14322
[SPARK-16689] [SQL] FileSourceStrategy: Pruning Partition Columns When No
Partition Column Exist in Project
### What changes were proposed in this pull request?
For partitioned file sources, the current implementation always scans all
the partition columns. However, this is not necessary when the projected column
list does not include any partition column. In addition, we also can avoid the
unnecessary Project.
Below is an example,
Below is an example,
```scala
spark
.range(N)
.selectExpr("id AS value1", "id AS value2", "id AS p1", "id AS p2", "id
AS p3")
.toDF("value", "value2", "p1", "p2", "p3").write.format("json")
.partitionBy("p1", "p2", "p3").save(tempDir)
```
```
spark.read.format("json").load(tempDir).selectExpr("value")
```
**Before the PR changes**, the physical plan is like:
```
== Physical Plan ==
*Project [value#37L]
+- *Scan json [value#37L,p1#39,p2#40,p3#41] Format: JSON, InputPaths:
file:/private/var/folders/4b/sgmfldk15js406vk7lw5llzw0000gn/T/spark-f7a4294a-2e1b-4f44-9ebb-1a5eb...,
PushedFilters: [], ReadSchema: struct<value:bigint>
```
**After the PR changes**, the physical plan becomes:
```
== Physical Plan ==
*Scan json [value#147L] Format: JSON, InputPaths:
file:/private/var/folders/4b/sgmfldk15js406vk7lw5llzw0000gn/T/spark-a5bcb14a-46c2-4c20-8f34-9662b...,
PushedFilters: [], ReadSchema: struct<value:bigint>
```
### How was this patch tested?
Added a test case to verify the results.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/gatorsmile/spark columnPruning
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14322.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 #14322
----
commit c1ff0465815f6adefb2b29c2973c9bc63aa13623
Author: gatorsmile <gatorsm...@gmail.com>
Date: 2016-07-23T00:59:14Z
solution1
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