Function convert_window_frame

nodedb-sql/src/planner/window/frame.rs:22–66

Convert a sqlparser `WindowFrame` to the executor's `WindowFrame`. `order_by` is needed for semantic validation: - GROUPS without ORDER BY is invalid (PostgreSQL parity). - RANGE with numeric offsets (Preceding(N)/Following(N)) requires a single numeric ORDER BY column; without one the semantics are undefined and we reject at plan time.

(
    frame: &ast::WindowFrame,
    order_by: &[SortKey],
)

///   numeric ORDER BY column; without one the semantics are undefined and we
///   reject at plan time.
pub(super) fn convert_window_frame(
    frame: &ast::WindowFrame,
    order_by: &[SortKey],
) -> Result<WindowFrame> {
    let mode = match frame.units {
        ast::WindowFrameUnits::Rows => "rows",
        ast::WindowFrameUnits::Range => "range",
        ast::WindowFrameUnits::Groups => {
            if order_by.is_empty() {
                return Err(SqlError::InvalidWindowFrame {
                    detail: "GROUPS mode requires an ORDER BY clause in the window specification"
                        .into(),
                });
            }
            "groups"
        }
    };

    let start = convert_window_frame_bound(&frame.start_bound)?;
    let end = match &frame.end_bound {
        Some(b) => convert_window_frame_bound(b)?,
        None => FrameBound::CurrentRow,
    };

    // RANGE with numeric offsets requires a single-column ORDER BY so we can
    // compare values. Reject if ORDER BY is absent or has more than one key
    // (multi-key RANGE offsets are undefined in SQL standards).
    if mode == "range" {
        let needs_order = matches!(start, FrameBound::Preceding(n) if n > 0)
            || matches!(start, FrameBound::Following(n) if n > 0)
            || matches!(end, FrameBound::Preceding(n) if n > 0)
            || matches!(end, FrameBound::Following(n) if n > 0);
        if needs_order && order_by.len() != 1 {
            return Err(SqlError::InvalidWindowFrame {
                detail: "RANGE with numeric PRECEDING/FOLLOWING offset requires exactly one ORDER BY column".into(),
            });
        }
    }

    Ok(WindowFrame {
        mode: mode.into(),
        start,
        end,
    })
}

fn convert_window_frame_bound(bound: &ast::WindowFrameBound) -> Result<FrameBound> {
    match bound {