Redis storing and getting multiple records

Question

I'm quite new to redis and have a task at hand to optimize redis operations for a dashboard of a non-profit.

The scenario:

• We have multiple cities (London, Rome,...)
• We have 1000s of users in each city

We have a need to load users from a particular city, and at the moment it is stored by city ID. As you can imagine, this results in a massive document that needs to be re-cached on every small change to the user.

I want to change this methodology so users are stored in Redis in the following format: [cityID][userID]. So if I need to pull all users from london, I can just call IDFORLONDON?

Would this be the correct way to approach it? Is there a way to load only 10 users from IDFORLONDON? (for pagination). Or is my option to load all and then slice?

Thank you!