Struct LastValueAggregator 

pub struct LastValueAggregator { /* private fields */ }

LAST_VALUE aggregator - returns the last value seen in a window.

Tracks the value with the latest timestamp in the window. For deterministic results, uses event timestamp, not arrival order. When timestamps are equal, the later arrival wins.

Example

use laminar_core::operator::window::LastValueAggregator;

// Track last (closing) price by timestamp
let last_price = LastValueAggregator::new(0, 1); // price col 0, timestamp col 1

Implementations

impl LastValueAggregator

pub fn new(value_column_index: usize, timestamp_column_index: usize) -> Self

Creates a new LAST_VALUE aggregator.

Arguments

• value_column_index - Column to extract value from
• timestamp_column_index - Column for event timestamp ordering

Trait Implementations

impl Aggregator for LastValueAggregator

type Acc = LastValueAccumulator

The accumulator type used by this aggregator.

fn create_accumulator(&self) -> LastValueAccumulator

Creates a new empty accumulator.

fn extract(&self, event: &Event) -> Option<(i64, i64)>

Extracts a value from an event to be aggregated.

fn output_data_type(&self) -> DataType

Returns the Arrow [DataType] for this aggregator’s output.

fn output_nullable(&self) -> bool

Returns whether the output is nullable (e.g., empty windows produce null).

fn extract_batch( &self, event: &Event, ) -> SmallVec<[<Self::Acc as Accumulator>::Input; 4]>

Extracts all values from a multi-row batch event.

impl Clone for LastValueAggregator

fn clone(&self) -> LastValueAggregator

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LastValueAggregator

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.