In-memory databases are different from the previous two types, as they're usually not structured, which means you have no tables. What you have is normally lists of some kind that you can look up and manipulate, or simple hash tables.
Taking advantage of the Redis instance we installed previously for Hydra, let's see another drawback, or actually feature, of this kind of database. Let's connect to our Redis instance and make the following sequence of instructions:
What we did here was to:
- Connect to the Redis service using redis-cli.
- Get the content of the counter, which is nil (nothing), because we haven't defined it yet.
- Increment ...