that appear only in sub-select
      target lists (Tom Lane)
     </P
><P
>      This mistake could result in outputs of an outer join incorrectly
      appearing as NULL.
     </P
></LI
><LI
><P
>      Allow the planner to assume that empty parent tables really are empty
      (Tom Lane)
     </P
><P
>      Normally an empty table is assumed to have a certain minimum size for
      planning purposes; but this heuristic seems to do more harm than good
      for the parent table of an inheritance hierarchy, 