Building Scalable Apps with Redis and Node.js

Redis persistence

Our example application has one big caveat. Every key that is added will not be removed. If we released something like this to the public, eventually Redis will fill up all the memory allotted to it. We can test this by connecting to Redis with redis-cli and running KEYS *. We will see that all of our users and messages are still in Redis. This will be true if we shut down the Redis server and bring it back up. Go ahead and restart Redis and then run KEYS * again. We still see the keys are there. Even though Redis is an in-memory key-value store, it persists data to the disk. We can see this happen. Redis will log in to the console when it saves to the disk. This will look like the following screenshot:

Then, when you launch Redis, ...