GitHub user viirya opened a pull request:
https://github.com/apache/spark/pull/16115
[SPARK-18667][PySpark][SQL] Change the way to group row in
BatchEvalPythonExec so input_file_name function can work with UDF in pyspark
## What changes were proposed in this pull request?
`input_file_name` doesn't return filename when working with UDF in PySpark.
An example shows the problem:
from pyspark.sql.functions import *
from pyspark.sql.types import *
def filename(path):
return path
sourceFile = udf(filename, StringType())
spark.read.json("tmp.json").select(sourceFile(input_file_name())).show()
+---+
|filename(input_file_name())|
+---+
| |
+---+
The cause of this issue is, we group rows in `BatchEvalPythonExec` for
batching processing of PythonUDF. Currently we group rows first and then
evaluate expressions on the rows. If the data is less than the required number
of rows for a group, the iterator will be consumed to the end before the
evaluation. However, once the iterator reaches the end, we will unset input
filename. So the input_file_name expression can't return correct filename.
This patch fixes the approach to group the batch of rows. We evaluate the
expression first and then group evaluated results to batch.
## How was this patch tested?
Added unit test to PySpark.
Please review http://spark.apache.org/contributing.html before opening a
pull request.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/viirya/spark-1 fix-py-udf-input-filename
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16115.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 #16115
commit 7cd606b6605ac75f311dca2cff988f20ba0ad7a0
Author: Liang-Chi Hsieh
Date: 2016-12-02T05:50:47Z
Change the way to group row in BatchEvalPythonExec so udf works with
input_file_name in pyspark.
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