pg_on_connection_loss creates, changes, or cancels
a request to execute a callback command if an unexpected loss of connection
to the database occurs.
With a callbackCommand
parameter, the request is established, or the command string of an already
existing request is replaced. With no callbackCommand
parameter, a prior request is canceled.
The callback command string is executed from the Tcl idle loop. That is the
normal idle state of an application written with Tk. In non-Tk Tcl shells,
execute update or vwait to cause
the idle loop to be entered.