>)</DT
><DD
><P
>        Controls the query planner's use of table constraints to
        optimize queries.
        The allowed values of <TT
CLASS="VARNAME"
>constraint_exclusion</TT
> are
        <TT
CLASS="LITERAL"
>on</TT
> (examine constraints for all tables),
        <TT
CLASS="LITERAL"
>off</TT
> (never examine constraints), and
        <TT
CLASS="LITERAL"
>partition</TT
> (examine constraints only for inheritance child
        tables and <TT
CLASS="LITERAL"
>UNION ALL</TT
> subqueries).
        <TT
