If this optional parameter is set to non-zero, it specifies
the time period in seconds that ClientListSQL will refresh its client list
by rereading the database. If set to 0, then ClientListSQL will only read
the client list from the database once at startup and on SIGHUP. Defaults
to 0. The % formats are permitted.
When the RefreshPeriod expires
and the list of clients is read from the SQL database, any Clients
previously created by this ClientList are cleared and a new set of clients
read from the database. This means that Clients defined in the
configuration file will not be removed. It also means that multiple
ClientListSQL clauses with non-zero RefreshPeriods will not remove each
others Clients.
# Reread the client list every hour
RefreshPeriod 3600