Feature request concerning postmaster log file.

Hi to all,
Could it be possible to have informations about who do what on any tablespace
or database logged in separate files, as samba does.
I don't think that it should be the default way, since the way events are
logged by now seems to please all users, but I'd think that a run-time option
could do the stuff.
The thing I have in mind is the following :
if the run-time option is chosen, any message issued by any command, from
connexion to all sql commands launched in any way by a user should go in a
separate log file, that could be named log.username for example.
Every message provided by the backend could go in the main logfile, as it does
by now. One could even imagine that every back-end program could have it's
own logfile (I think of autovac, bgwriter and so on).
This is the way samba daemon can be tuned, and I find it very usefull, when
one have to track an error found by one user.
Let me know if you find this idea usefull.
Thanks.