Struct RetractableFirstValueAccumulator 

pub struct RetractableFirstValueAccumulator { /* private fields */ }

Retractable FIRST_VALUE accumulator for changelog/retraction mode.

Stores all (timestamp, value) entries sorted by timestamp ascending. On retraction, removes the entry and recomputes the first value. This is necessary for EMIT CHANGES with OHLC queries where the open price may need to be retracted.

Ring Architecture

This is a Ring 1 structure (allocates). Ring 0 uses the non-retractable super::window::FirstValueAccumulator via the static dispatch path.

Uses BTreeMap<i64, Vec<i64>> (timestamp → values) for O(log n) insert/remove and O(1) first-value access via first_key_value().

Implementations

impl RetractableFirstValueAccumulator

pub fn new() -> Self

Creates a new empty accumulator.

pub fn len(&self) -> usize

Returns the number of stored entries.

pub fn is_empty(&self) -> bool

Returns true if no entries are stored.

Trait Implementations

impl Clone for RetractableFirstValueAccumulator

fn clone(&self) -> RetractableFirstValueAccumulator

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RetractableFirstValueAccumulator

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

Formats the value using the given formatter.

impl Default for RetractableFirstValueAccumulator

fn default() -> RetractableFirstValueAccumulator

Returns the “default value” for a type.

impl RetractableAccumulator for RetractableFirstValueAccumulator

type Input = (i64, i64)

The input type for the aggregation.

type Output = Option<i64>

The output type produced by the aggregation.

fn add(&mut self, (timestamp, value): (i64, i64))

Adds a value to the accumulator.

fn retract(&mut self, (timestamp, value): &(i64, i64))

Retracts (un-applies) a value from the accumulator.

fn merge(&mut self, other: &Self)

Merges another accumulator into this one.

fn result(&self) -> Option<i64>

Extracts the final result from the accumulator.

fn is_empty(&self) -> bool

Returns true if the accumulator is empty (no values added).

fn supports_efficient_retraction(&self) -> bool

Returns true if this accumulator can efficiently retract.

fn reset(&mut self)

Resets the accumulator to its initial state.