GitHub user HyukjinKwon opened a pull request:
https://github.com/apache/spark/pull/17256
[SPARK-19919][SQL] Defer throwing the exception for empty paths in CSV
datasource into `DataSource`
## What changes were proposed in this pull request?
This PR proposes to defer throwing the exception within `DataSource`.
Currently, if other datasources fail to infer the schema, it returns `None`
and then this is being validated in `DataSource` as below:
```
scala> spark.read.json("emptydir")
org.apache.spark.sql.AnalysisException: Unable to infer schema for JSON. It
must be specified manually.;
```
```
scala> spark.read.orc("emptydir")
org.apache.spark.sql.AnalysisException: Unable to infer schema for ORC. It
must be specified manually.;
```
```
scala> spark.read.parquet("emptydir")
org.apache.spark.sql.AnalysisException: Unable to infer schema for Parquet.
It must be specified manually.;
```
However, CSV it checks it within the datasource implementation and throws
another exception message as below:
```
scala> spark.read.csv("emptydir")
java.lang.IllegalArgumentException: requirement failed: Cannot infer schema
from an empty set of files
```
We could remove this duplicated check and validate this in one place in the
same way with the same message.
## How was this patch tested?
Unit test in `CSVSuite` and manual test.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/HyukjinKwon/spark SPARK-19919
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17256.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 #17256
----
commit 9d91da124e0723adee7744a64999ea1c07acfe66
Author: hyukjinkwon <[email protected]>
Date: 2017-03-11T06:53:39Z
Defer input path validation into DataSource in CSV datasource
----
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