2
CLASS="SECT2"
><A
NAME="AEN56780"
>38.2.3. The Power of Views in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></A
></H2
><P
>    The above demonstrates how the rule system incorporates view
    definitions into the original query tree. In the second example, a
    simple <TT
CLASS="COMMAND"
>SELECT</TT
> from one view created a final
    query tree that is a join of 4 tables (<TT
CLASS="LITERAL"
>unit</TT
> was used twice with
    different names).</P
><P
>    The benefit of implementing views with the ru