/P
><P
>       The access method must identify any rows which might violate the
       unique constraint, but it is not an error for it to report false
       positives. This allows the check to be done without waiting for other
       transactions to finish; conflicts reported here are not treated as
       errors and will be rechecked later, by which time they may no longer
       be conflicts.
      </P
></LI
><LI
><P
>       <TT
CLASS="LITERAL"
>UNIQUE_CHECK_EXISTING</TT
> indicates that this is a defer