Richard Hayward <richard@tortoise.demon.co.uk> writes:
> Is it possible to prevent a user from changing their password?

No.

> I have a database with a 'Guest' account, that will have limited
> access. I don't want any of my guests to change the Guest account
> password.

Perhaps you should use something other than password authentication
for the guest account.

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match