GitHub user lw-lin opened a pull request:
https://github.com/apache/spark/pull/13705
[SPARK-15472][SQL] Add support for writing in `csv` format in Structured
Streaming
## What changes were proposed in this pull request?
This patch adds support for writing in `csv` format in Structured Streaming:
**1. At a high level, this patch forms the following class hierarchy**:
```
<OutputWriter>
â
CSVOutputWriterBase
â â
(anonymous batch) CSVOutputWriter (anonymous streaming) CSVOutputWriter
[write data without using
an OutputCommitter]
```
```
<OutputWriterFactory>
â â
BatchCSVOutputWriterFactory StreamingCSVOutputWriterFactory
```
The streaming CSVOutputWriter would write data **without** using an
`OutputCommitter`, which was the same approach taken by
[SPARK-14716](https://github.com/apache/spark/pull/12409).
**2. To support compression, this patch attaches an extension to the path
assigned by `FileStreamSink`**.
E.g., if we write out using the `gzip` compression and `FileStreamSink`
assigns path `${uuid}` to the output writer, then in the end the file written
out will be `${uuid}.csv.gz`. This way when we read the file back, we should be
able to interpret it correctly as `gzip` compressed.
This is slightly different from
[SPARK-14716](https://github.com/apache/spark/pull/12409).
## How was this patch tested?
`FileStreamSinkSuite` is expanded to cover `csv` format:
```scala
test("csv - unpartitioned data - codecs: none/gzip")
test("csv - partitioned data - codecs: none/gzip")
test("csv - unpartitioned writing and batch reading - codecs: none/gzip")
test("csv - partitioned writing and batch reading - codecs: none/gzip")
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/lw-lin/spark csv-for-ss
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/13705.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 #13705
----
commit 9869f9885e4fdc7364cd46ab05b1f332921ff8d7
Author: Liwei Lin <lwl...@gmail.com>
Date: 2016-06-16T05:38:13Z
Add support for writing in `csv` format
----
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