code> clause as filtered by its
    <code class="literal">WHERE</code>, <code class="literal">GROUP BY</code>, and <code class="literal">HAVING</code> clauses
    if any.  For example, a row removed because it does not meet the
    <code class="literal">WHERE</code> condition is not seen by any window function.
    A query can contain multiple window functions that slice up the data
    in different ways using different <code class="literal">OVER</code> clauses, but
    they all act on the same collection o