pyflink.table.udf.AggregateFunction#
- class AggregateFunction[source]#
Base interface for user-defined aggregate function. A user-defined aggregate function maps scalar values of multiple rows to a new scalar value.
New in version 1.12.0.
Methods
accumulate
(accumulator, *args)Processes the input values and updates the provided accumulator instance.
close
()Tear-down method for the user code.
create_accumulator
()Creates and initializes the accumulator for this AggregateFunction.
get_accumulator_type
()Returns the DataType of the AggregateFunction's accumulator.
get_result_type
()Returns the DataType of the AggregateFunction's result.
get_value
(accumulator)Called every time when an aggregation result should be materialized.
is_deterministic
()Returns information about the determinism of the function's results.
merge
(accumulator, accumulators)Merges a group of accumulator instances into one accumulator instance.
open
(function_context)Initialization method for the function.
retract
(accumulator, *args)Retracts the input values from the accumulator instance.The current design assumes the inputs are the values that have been previously accumulated.