Redis, session expiration, and reverse lookup

Question

I\'m currently bulding a web app and would like to use Redis to store sessions. At login, the session is inserted into Redis with a corresponding user id, and expiration set at

Answer 1

In more recent versions of Redis (2.8.0 and up) Keyspace Notifications for expired events are supported. I.e. when a key with a TTL expires this event is triggered.

This is what to subscribe to:

'__keyevent@0__:expired'

So subscribing to this event allows you to have a single index for all sessions and you can remove the key from the index when the key expires.

Example:

Use a sorted set as a secondary index with the uid as the weight:

ZADD "idx-session-uid"  

Search for sessionkeys for a specific user with:

ZRANGEBYSCORE "idx-session-uid"  

When a session is deleted or expired we do:

ZREM "idx-session-uid"