I'm confused at that...
There seem to be ways at time of connection establishment, whether via
the psql "-U" option, or the PGconnect "dbuser=foo" option, or during
a psql session via "\c - newuser"
In what way do those not represent "assumption of a user's identity"?
--
wm(X,Y):-write(X),write('@'),write(Y). wm('cbbrowne','gmail.com').
http://www3.sympatico.ca/cbbrowne/linuxxian.html
"In the long run every program becomes rococo - then rubble."
-- Alan Perlis