Function apply_aggregate_window

nodedb-query/src/window/aggregate.rs:20–47

(
    rows: &mut [(String, serde_json::Value)],
    indices: &[usize],
    spec: &WindowFuncSpec,
)

use super::spec::{FrameBound, WindowFuncSpec};

pub(super) fn apply_aggregate_window(
    rows: &mut [(String, serde_json::Value)],
    indices: &[usize],
    spec: &WindowFuncSpec,
) {
    let field = spec
        .args
        .first()
        .and_then(|e| match e {
            SqlExpr::Column(c) => Some(c.as_str()),
            _ => None,
        })
        .unwrap_or("*");

    // Fast path: RANGE UNBOUNDED PRECEDING TO CURRENT ROW is the most common
    // pattern (the PostgreSQL default for ordered windows). Use the running
    // accumulator rather than re-aggregating the slice from scratch each row.
    let use_running = spec.frame.mode == "range"
        && matches!(spec.frame.start, FrameBound::UnboundedPreceding)
        && matches!(spec.frame.end, FrameBound::CurrentRow);

    if use_running {
        running_aggregate(rows, indices, spec, field);
        return;
    }

    per_row_aggregate(rows, indices, spec, field);
}

/// Per-row frame evaluator.
///