GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/spark/pull/13486
[SPARK-15743][SQL] Prevent saving with all-column partitioning
## What changes were proposed in this pull request?
When saving datasets on storage, `partitionBy` provides an easy way to
construct the directory structure. However, if a user choose all columns as
partition columns, some exceptions occurs.
- **ORC with all column partitioning**: `AnalysisException` on **future
read** due to schema inference failure.
```
scala>
spark.range(10).write.format("orc").mode("overwrite").partitionBy("id").save("/tmp/data")
scala> spark.read.format("orc").load("/tmp/data").collect()
org.apache.spark.sql.AnalysisException: Unable to infer schema for ORC at
/tmp/data. It must be specified manually;
```
- **Parquet with all-column partitioning**: `InvalidSchemaException` on
**write execution** due to Parquet limitation.
```
scala>
spark.range(100).write.format("parquet").mode("overwrite").partitionBy("id").save("/tmp/data")
[Stage 0:> (0 + 8)
/ 8]16/06/02 16:51:17
ERROR Utils: Aborting task
org.apache.parquet.schema.InvalidSchemaException: A group type can not be
empty. Parquet does not support empty group without leaves. Empty group:
spark_schema
... (lots of error messages)
```
Although some formats like JSON support all-column partitioning without any
problem, it seems not a good idea to make lots of empty directories.
This PR prevents saving with all-column partitioning by consistently
raising `AnalysisException` before saving.
## How was this patch tested?
Newly added `PartitioningUtilsSuite`.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/spark SPARK-15743
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/13486.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 #13486
----
commit bb97467dba96604d26d45763f4115152640ff189
Author: Dongjoon Hyun <dongj...@apache.org>
Date: 2016-06-02T23:14:50Z
[SPARK-15743][SQL] Prevent saving with all-column partitioning
----
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