am company.
    The company measures peak temperatures every day as well as ice cream
    sales in each region. Conceptually, we want a table like:

</p><pre class="programlisting">
CREATE TABLE measurement (
    city_id         int not null,
    logdate         date not null,
    peaktemp        int,
    unitsales       int
);
</pre><p>

    We know that most queries will access just the last week's, month's or
    quarter's data, since the main use of this table will be to prepare
    online reports for m