ns unless the conflict check is an integral part
   of insertion of the new index entry.
  </P
><P
>   If the unique constraint is deferrable, there is additional complexity:
   we need to be able to insert an index entry for a new row, but defer any
   uniqueness-violation error until end of statement or even later.  To
   avoid unnecessary repeat searches of the index, the index access method
   should do a preliminary uniqueness check during the initial insertion.
   If this shows that there is definitel