How does Rails know when to delete a record from the `sessions` table?

Question

How does Rails know when to delete a record from the sessions table?

For example, if a user visits the website, a session record is created, but when the user closes the browser window, the server doesn't get any notification, so how does Rails delete records from sessions table?

Answer 1

There are simplier ways:

ActiveRecord::SessionStore::Session.delete_all(["updated_at < ?", 12.hours.ago])

You can call it after some Action in Controller and this piece of code kill all dead sessions.

Of course it is disputable technique, but the simplest.

Full story

Answer 2

You have to provide your own implementation of session expiration, to my understanding.

This API page gives you a pretty decent answer to how that works. You create your database table with the extra attributes created_on and updated_at (and you get timestamps for free) and then you just create a job to expire them whenever you want by looking at the updated_at attribute.

This post has details of how to run a job.