Enum AggSpec 

pub enum AggSpec {
    Count,
    Sum(ColId),
    Avg(ColId),
}

Which aggregate a Reduce column computes, in output-column order (REDUCE-DESIGN.md §5). All three are invertible — a Remove folds into a fixed-size accumulator without re-reading the inputs — which is what lets Reduce maintain them from a pure delta stream.

Variants

Count

count(*) — counts input rows (NULLs included). Add +1, Remove -1.

Sum(ColId)

sum(col) — Σ of the column’s non-NULL values. Add +v, Remove -v.

Avg(ColId)

avg(col) — sum(col) / count(col) over non-NULL values (SQL semantics: the denominator is the non-NULL count, not count(*)); NULL on empty.

Implementations

impl AggSpec

pub fn output_type(&self, input: &Schema) -> ValueType

The declared ValueType of this aggregate’s output column (design 226 §4.1): count and avg are Number; sum follows its input column — Int over a declared int64 input (the exact-i64 sum plane), Number otherwise. Shared by Reduce::with_input_types and the builder’s view-schema twins so the two derivations cannot drift.

Trait Implementations

impl Clone for AggSpec

fn clone(&self) -> AggSpec

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AggSpec

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

Formats the value using the given formatter.