input tables. As with <literal>USING</literal>, these columns appear
only once in the output table. If there are no common
column names, <literal>NATURAL JOIN</literal> behaves like
- <literal>JOIN ... ON TRUE</literal>, producing a cross-product join.
+ <literal>CROSS JOIN</literal>.
</para>
<note>
<para>
If multiple grouping items are specified in a single <literal>GROUP BY</literal>
- clause, then the final list of grouping sets is the cross product of the
+ clause, then the final list of grouping sets is the Cartesian product of the
individual items. For example:
<programlisting>
GROUP BY a, CUBE (b, c), GROUPING SETS ((d), (e))