Revert "Add examples and tests for registering and using Python UDTFs"

This reverts commit 855e8cc.

Author: kosiew

docs/source/user-guide/common-operations/udf-and-udfa.rst

@@ -254,26 +254,6 @@ Provider as described in the ref:`_io_custom_table_provider` page.
 Once you have a table function, you can register it with the session context
 by using :py:func:`datafusion.context.SessionContext.register_udtf`.
 
-.. code-block:: python
-
-    from datafusion import SessionContext, Table, udtf
-
-    ctx = SessionContext()
-
-    @udtf("table_from_sql")
-    def table_from_sql_udtf() -> Table:
-        return Table.from_dataframe(ctx.sql("SELECT 1 AS value"))
-
-    ctx.register_udtf(table_from_sql_udtf)
-
-    ctx.sql("SELECT * FROM table_from_sql()").show()
-
-.. note::
-
-    The ``TABLE(...)`` wrapper syntax is not currently implemented for
-    invoking table functions from SQL. Call the function directly instead,
-    such as ``SELECT * FROM my_table_function()``.
-
 There are examples of both rust backed and python based table functions in the
 examples folder of the repository. If you have a rust backed table function
 that you wish to expose via PyO3, you need to expose it as a ``PyCapsule``.

examples/python-udtf-table-capsule-regression.py

@@ -19,10 +19,10 @@ def table_from_sql_udtf() -> Table:
 
     ctx.register_udtf(table_from_sql_udtf)
 
-    result = ctx.sql("SELECT * FROM table_from_sql()").collect()
-    as_pydict = [batch.to_pydict() for batch in result]
-    print("table_from_sql() returned:", as_pydict)
-    assert as_pydict == [{"value": [1]}]
+    try:
+        ctx.sql("SELECT * FROM table(table_from_sql())").collect()
+    except NotImplementedError as err:
+        print("Collecting from table_from_sql() failed:", err)
 
     ctx.register_table("numbers", Table(ctx.sql("SELECT 1 AS value")))
 

python/tests/test_context.py

@@ -31,7 +31,6 @@
     Table,
     column,
     literal,
-    udtf,
 )
 
 
@@ -116,21 +115,6 @@ def test_register_record_batches(ctx):
     assert result[0].column(1) == pa.array([-3, -3, -3])
 
 
-def test_register_python_table_function(ctx):
-    @udtf("table_from_sql")
-    def table_from_sql_udtf() -> Table:
-        return Table.from_dataframe(
-            ctx.sql("SELECT 1 AS value UNION ALL SELECT 2 AS value")
-        )
-
-    ctx.register_udtf(table_from_sql_udtf)
-
-    result = ctx.sql("SELECT * FROM table_from_sql() ORDER BY value").collect()
-    table = pa.Table.from_batches(result)
-
-    assert table.to_pydict() == {"value": [1, 2]}
-
-
 def test_create_dataframe_registers_unique_table_name(ctx):
     # create a RecordBatch and register it as memtable
     batch = pa.RecordBatch.from_arrays(