GitHub user cloud-fan opened a pull request:
https://github.com/apache/spark/pull/16100
[SPARK-18674][SQL] improve the error message of natural join
## What changes were proposed in this pull request?
The current error message of USING join is quite confusing, for example:
```
scala> val df1 = List(1,2,3).toDS.withColumnRenamed("value", "c1")
df1: org.apache.spark.sql.DataFrame = [c1: int]
scala> val df2 = List(1,2,3).toDS.withColumnRenamed("value", "c2")
df2: org.apache.spark.sql.DataFrame = [c2: int]
scala> df1.join(df2, usingColumn = "c1")
org.apache.spark.sql.AnalysisException: using columns ['c1] can not be
resolved given input columns: [c1, c2] ;;
'Join UsingJoin(Inner,List('c1))
:- Project [value#1 AS c1#3]
: +- LocalRelation [value#1]
+- Project [value#7 AS c2#9]
+- LocalRelation [value#7]
```
after this PR, it becomes:
```
scala> val df1 = List(1,2,3).toDS.withColumnRenamed("value", "c1")
df1: org.apache.spark.sql.DataFrame = [c1: int]
scala> val df2 = List(1,2,3).toDS.withColumnRenamed("value", "c2")
df2: org.apache.spark.sql.DataFrame = [c2: int]
scala> df1.join(df2, usingColumn = "c1")
org.apache.spark.sql.AnalysisException: USING column `c1` can not be
resolved with the right join side, the right output is: [c2];
```
## How was this patch tested?
updated tests
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/cloud-fan/spark natural
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16100.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 #16100
----
commit 94618392045e86498902cb779b07fe88cf10e6de
Author: Wenchen Fan <[email protected]>
Date: 2016-12-01T14:21:39Z
improve the error message of natural join
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