Ratnakar,
Access policy defaults in postgresql installation enforce identity constraints, i.e. the _postgresql user_ == _connecting system user_ ... i assume you try to by calling sth. like:
~# psql -U postgres [...]
BUT not being logged-in as postgres user (or under camouflage = sudo).
1. make sure you are logged-in/ camouflaged as the postgresql user in your system environment
2. change the access policy in pg_hba.conf from ident to something other, i.e. trust or the like
//stefan
