[Zope] ZSQL with different user

Hello, I'm developing a Zope application that uses a PostgreSQL connection and several ZSQL objects. People should log in using a Postgres user and ZSQL object should be executed by the user that's logged in. Multiple people can be logged at the same time. Unfortunately it is not possible because the same Postgres connection is used by all the ZSQL object. Is there a way to change the user executing a ZSQL query? An alternative would be to log into the event.log some information (like the username, that's stored in the session) and the query source. Can you point me to some information? Thanks