SteNicholas commented on a change in pull request #12476:
URL: https://github.com/apache/flink/pull/12476#discussion_r436477330
##
File path: flink-python/pyflink/table/table_environment.py
##
@@ -166,11 +169,254 @@ def unload_module(self, module_name: str):
ValidationException is thrown when there is no module with the given
name.
:param module_name: Name of the :class:`~pyflink.table.Module`.
+:type module_name: str
.. versionadded:: 1.12.0
"""
self._j_tenv.unloadModule(module_name)
+def create_java_temporary_system_function(self, name: str,
function_class_name: str):
+"""
+Registers a java user defined function class as a temporary system
function.
+
+Compared to .. seealso:: :func:`create_temporary_function`, system
functions are identified
+by a global name that is independent of the current catalog and
current database. Thus,
+this method allows to extend the set of built-in system functions like
TRIM, ABS, etc.
+
+Temporary functions can shadow permanent ones. If a permanent function
under a given name
+exists, it will be inaccessible in the current session. To make the
permanent function
+available again one can drop the corresponding temporary system
function.
+
+Example:
+::
+
+>>> table_env.create_java_temporary_system_function("func",
+... "java.user.defined.function.class.name")
+
+:param name: The name under which the function will be registered
globally.
+:type name: str
+:param function_class_name: The java full qualified class name of the
function class
+containing the implementation. The
function must have a
+public no-argument constructor and can be
founded in current
+Java classloader.
+:type function_class_name: str
+
+.. versionadded:: 1.12.0
+"""
+gateway = get_gateway()
+java_function =
gateway.jvm.Thread.currentThread().getContextClassLoader() \
+.loadClass(function_class_name)
+self._j_tenv.createTemporarySystemFunction(name, java_function)
+
+def create_temporary_system_function(self, name: str,
+ function: UserDefinedFunctionWrapper):
+"""
+Registers a python user defined function class as a temporary system
function.
+
+Compared to .. seealso:: :func:`create_temporary_function`, system
functions are identified
+by a global name that is independent of the current catalog and
current database. Thus,
+this method allows to extend the set of built-in system functions like
TRIM, ABS, etc.
+
+Temporary functions can shadow permanent ones. If a permanent function
under a given name
+exists, it will be inaccessible in the current session. To make the
permanent function
+available again one can drop the corresponding temporary system
function.
+
+Example:
+::
+
+>>> table_env.create_temporary_system_function(
+... "add_one", udf(lambda i: i + 1, DataTypes.BIGINT(),
DataTypes.BIGINT()))
+
+>>> @udf(input_types=[DataTypes.BIGINT(), DataTypes.BIGINT()],
+... result_type=DataTypes.BIGINT())
+... def add(i, j):
+... return i + j
+>>> table_env.create_temporary_system_function("add", add)
+
+>>> class SubtractOne(ScalarFunction):
+... def eval(self, i):
+... return i - 1
+>>> table_env.create_temporary_system_function(
+... "subtract_one", udf(SubtractOne(), DataTypes.BIGINT(),
DataTypes.BIGINT()))
+
+:param name: The name under which the function will be registered
globally.
+:type name: str
+:param function: The function class containing the implementation. The
function must have a
+ public no-argument constructor and can be founded in
current Java
+ classloader.
+:type function: pyflink.table.udf.UserDefinedFunctionWrapper
+
+.. versionadded:: 1.12.0
+"""
+java_function = function.java_user_defined_function()
+self._j_tenv.createTemporarySystemFunction(name, java_function)
+
+def drop_temporary_system_function(self, name: str):
+"""
+Drops a temporary system function registered under the given name.
+
+If a permanent function with the given name exists, it will be used
from now on for any
+queries that reference this name.
+
+:param name: The name under which the function has been registered
globally.
+:type name: str
+:return: true if a function existed under the given name and was
removed.
+:rtype: bool
+
+
