GitHub user davies opened a pull request:
https://github.com/apache/spark/pull/12014
[SPARK-14125] [SQL] [PYSPARK] Support chained Python UDFs
## What changes were proposed in this pull request?
This PR brings the support for chained Python UDFs, for example
```sql
select udf1(udf2(a))
select udf1(udf2(a) + 3)
select udf1(udf2(a) + udf3(b))
```
Also directly chained Python UDFs are put in single batch of Python UDFs,
others may require multiple batches.
For example,
```python
>>> sqlContext.sql("select double(double(1))").explain()
== Physical Plan ==
WholeStageCodegen
: +- Project [pythonUDF#10 AS double(double(1))#9]
: +- INPUT
+- !BatchPythonEvaluation double(double(1)), [pythonUDF#10]
+- Scan OneRowRelation[]
>>> sqlContext.sql("select double(double(1) + double(2))").explain()
== Physical Plan ==
WholeStageCodegen
: +- Project [pythonUDF#19 AS double((double(1) + double(2)))#16]
: +- INPUT
+- !BatchPythonEvaluation double((pythonUDF#17 + pythonUDF#18)),
[pythonUDF#17,pythonUDF#18,pythonUDF#19]
+- !BatchPythonEvaluation double(2), [pythonUDF#17,pythonUDF#18]
+- !BatchPythonEvaluation double(1), [pythonUDF#17]
+- Scan OneRowRelation[]
```
## How was this patch tested?
Added new unit tests for chained UDFs.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/davies/spark py_udfs
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/12014.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 #12014
----
commit d63ec844576bfe47fc0b78ddba4693e4210bd595
Author: Davies Liu <dav...@databricks.com>
Date: 2016-03-28T20:21:07Z
use row based function for Python UDF
commit 024a82236f09a6b6ec09aeb41ca161e6c7c72dda
Author: Davies Liu <dav...@databricks.com>
Date: 2016-03-28T20:59:35Z
support chained Python UDFs
----
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