Availability of pg_backend_pid() immediately after connection establishment

[Hari Bhaskaran <hbhaskaran@xxxxxxxxx>]

Someone in this group mentioned a while back that pg_backend_pid() 
function works only after some 1/2 second after the connection has been 
established.  This had something to do with the stats collector to make 
its sweep every .5 seconds?.  Does anyone have more information on this?

Any help is appreciated
--
Hari