I am storing a variety of data on app_metadata and user_metadata. However, I came upon this text in auth0 docs:
Beware of storing too much data in the Auth0 profile. This data is intended to be used for authentication and authorization purposes. The metadata and search capabilities of Auth0 are not designed for marketing research or anything else that requires heavy search or update frequency. Your system is likely to run into scalability and performance issues if you use Auth0 for this purpose. A better approach is to store data in an external system and store a pointer (the user ID) in Auth0 so that backend systems can fetch the data if needed. A simple rule to follow is to store only items that you plan to use in rules to add to tokens or make decisions.
So now I am confused…what exactly should I store on metadata? And if I cannot store some stuff on metadata do I store it in a separate DB, like mongoDB. I thought that having a DB connection costs money. I am currently on the free tier, and this suites my use case for now, until we scale up. Clarification would be appreciated!