GitHub user gatorsmile opened a pull request:
https://github.com/apache/spark/pull/14954
[SPARK-17393] [SQL] Error Handling when CTAS Against the Same Data Source
Table Using Overwrite Mode
### What changes were proposed in this pull request?
When we trying to read a table and then write to the same table using the
`Overwrite` save mode, we got a very confusing error message:
For example,
```Scala
Seq((1, 2)).toDF("i", "j").write.saveAsTable("tab1")
table("tab1").write.mode(SaveMode.Overwrite).saveAsTable("tab1")
```
```
Job aborted.
org.apache.spark.SparkException: Job aborted.
at
org.apache.spark.sql.execution.datasources.InsertIntoHadoopFsRelationCommand$$anonfun$run$1.apply$mcV$sp
...
Caused by: org.apache.spark.SparkException: Task failed while writing rows
at
org.apache.spark.sql.execution.datasources.DefaultWriterContainer.writeRows(WriterContainer.scala:266)
at
org.apache.spark.sql.execution.datasources.InsertIntoHadoopFsRelationCommand$$anonfun$run$1$$anonfun$apply$mcV$sp$1.apply(InsertIntoHadoopFsRelationCommand.scala:143)
at org.apache.spark.sql.execution.datasources
```
After the PR, we will issue an `AnalysisException`:
```
Cannot overwrite table `tab1` that is also being read from
```
### How was this patch tested?
Added test cases.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/gatorsmile/spark ctasQueryAnalyze
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14954.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 #14954
----
commit 85e51dc6361b3607fafc95021d93f791f5947080
Author: gatorsmile <gatorsm...@gmail.com>
Date: 2016-09-04T06:49:41Z
fix.
----
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