allisonwang-db opened a new pull request, #41316:
URL: https://github.com/apache/spark/pull/41316
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### What changes were proposed in this pull request?
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This PR adds the initial support for Python user-defined table functions. It
allows users to create UDTFs in PySpark and use them in PySpark and SQL.
Here are examples of creating and using Python UDTFs:
```python
# Implement the UDTF class
class TestUDTF:
def __init__(self):
...
def eval(self, *args):
yield "hello", "world"
def terminate(self):
...
# Create the UDTF
from pyspark.sql.functions import udtf
test_udtf = udtf(TestUDTF, returnType="c1: string, c2: string")
# Invoke the UDTF
test_udtf().show()
+-----+-----+
| c1| c2|
+-----+-----+
|hello|world|
+-----+-----+
# Register the UDTF
spark.udtf.register(name="test_udtf", f=test_udtf)
# Invoke the UDTF in SQL
spark.sql("SELECT * FROM test_udtf()").show()
+-----+-----+
| c1| c2|
+-----+-----+
|hello|world|
+-----+-----+
```
Please note that this is the initial PR, and there will be subsequent
follow-up work to make it more user-friendly and performant.
### Why are the changes needed?
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To support another type of user-defined function in PySpark.
### Does this PR introduce _any_ user-facing change?
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the documentation fix.
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Yes. After this PR, users can create Python user-defined table functions.
### How was this patch tested?
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New unit tests.
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