Module first_last

Defines the FIRST_VALUE/LAST_VALUE aggregations.

Structs

FirstValue

FirstValueAccumulator

LastValue

TrivialFirstValueAccumulator

This accumulator is used when there is no ordering specified for the FIRST_VALUE aggregation. It simply returns the first value it sees according to the pre-existing ordering of the input data, and provides a fast path for this case without needing to maintain any ordering state.

TrivialLastValueAccumulator

This accumulator is used when there is no ordering specified for the LAST_VALUE aggregation. It simply updates the last value it sees according to the pre-existing ordering of the input data, and provides a fast path for this case without needing to maintain any ordering state.

Functions

first_value

Returns the first value in a group of values.

first_value_udaf

AggregateFunction that returns a AggregateUDF for FirstValue

last_value

Returns the last value in a group of values.

last_value_udaf

AggregateFunction that returns a AggregateUDF for LastValue