 no daemon or server process, and
    signals or a signal handler cannot be used. Therefore, the
    <TT
CLASS="VARNAME"
>restore_command</TT
> is not suitable to trigger failover.
    It is possible to use a simple timeout facility, especially if
    used in conjunction with a known <TT
CLASS="VARNAME"
>archive_timeout</TT
>
    setting on the primary. However, this is somewhat error prone
    since a network problem or busy primary server might be sufficient
    to initiate failover. A notification mechan