PostgreSQL 9 Administration Cookbook - Second Edition

Restricting users to only one session each

If resources need to be closely controlled, you may wish to restrict users so that they can only connect at most once to the server. The same technique can be used to prevent connections entirely for that user.

How to do it…

We can restrict users to only one connection using the following command:

postgres=# ALTER ROLE fred CONNECTION LIMIT 1;
ALTER ROLE

This will then cause any additional connections to receive the error message:

FATAL: too many connections for role "fred".

You can eliminate this restriction by setting the value to -1.

It's possible to set the limit to zero or any positive integer. You can set this to a number other than max_connections, though it is up to you to make sense of that if you ...