Say I have a collection of Users. Each user has a User_ID, Username and Tenant_ID.
Sometimes I need all Users for a specific Tenant_ID.
Sometimes I need a specific User based on User_ID“.
Sometimes I need a User based on Username.
I will always have the Tenant_ID available to use as part of the lookup.
What is the ideal way to implement a cache layer for this data?
What considerations should I make since I’m dealing with a multi-tenant system?
What is the best way to manage all the possible cache keys involved?
Option #1: Store all Users together under a single key of “Tenant_1_Users”
The problem with this is that I will be transferring a lot of unwanted data over the wire. If I just need to find a specific user then I need to do the lookup in code using LINQ or something after retrieving the whole collections.
Option #2: Duplicate the same User object under different keys such as “TenantID_1_UserID_5” and “TenantID_1_Username_Jason”.
The problem here is managing all the various Keys and location of User objects. Especially if I need to flush a specific User because it has been updated in the database. I now need to know all the possible places it could be stored. Also uses more memory since the same User can be under different keys.
Related: AppFabric Cache 'Design' – Caching Individual Items or Collections?
The problem is that Azure AppFabric Caching does not support Regions, Tags or Notifications.
For what its worth, I would tend to not want to cache the same object under multiple keys, because if you need to update or delete that record later, you’ll have to remember to update/delete all the possible keys that it could have used.