问题
I'm trying to figure out of a way of knowing as soon as a user logs into a Postgres database. Is there a way to define a trigger to fire when a user logs into the DB? Or is there a table or a system view that gets updated whenever anyone logs into the DB?
回答1:
I don't think there's anything at the SQL level which can identify a logon event (i.e. no view you can query, and no trigger you can create).
You can, however, write a server-side module (in C) which intercepts logon events via the ClientAuthentication_hook. This hook is invoked after the server has attempted to authenticate a user, but before it has sent its response.
There is a worked example of a ClientAuthentication_hook on the Postgres wiki. You can also find a couple of examples of this hook in action within Postgres' own contrib modules.
回答2:
login_hook
Postgres database extension to execute som code on user login, comparable to Oracle's after logon trigger.
来源：https://stackoverflow.com/questions/48104368/postgresql-trigger-on-user-logon