he query planner's use of <ACRONYM
CLASS="ACRONYM"
>TID</ACRONYM
>
        scan plan types. The default is <TT
CLASS="LITERAL"
>on</TT
>.
       </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="RUNTIME-CONFIG-QUERY-CONSTANTS"
>18.7.2. Planner Cost Constants</A
></H2
><P
>     The <I
CLASS="FIRSTTERM"
>cost</I
> variables described in this section are measured
     on an arbitrary scale.  Only their relative values matter, hence
     scaling them all up or down by the same facto