Function mz_sql::plan::query::plan_function_order_by

fn plan_function_order_by(
    ecx: &ExprContext<'_>,
    order_by: &[OrderByExpr<Aug>],
) -> Result<(Vec<HirScalarExpr>, Vec<ColumnOrder>), PlanError>

Plans the ORDER BY clause of a window function.

Unfortunately, we have to create two HIR structs from an AST OrderByExpr: A ColumnOrder has asc/desc and nulls first/last, but can’t represent an HirScalarExpr, just a column reference by index. Therefore, we return both HirScalarExprs and ColumnOrders. Note that the column references in the ColumnOrders point NOT to input columns, but into the Vec<HirScalarExpr> that we return.