Hello everyone,

I'm working on a Next.js project with a private user area and I'm contemplating the best approach to cache server-side requests for authenticated user data.

Here's a scenario for clarity:

Public Access: Non-authenticated users fetch articles, caching them with an "articles" tag.
Editor Action: When an editor publishes a new article, we invalidate the "articles" tag using revalidateTag, prompting a fresh fetch for non-authenticated users.

Now, consider adding a subscription feature:

Authenticated Access: Users fetch their subscriptions, caching them with a "subscriptions" tag.
Subscription Update: A user modifies their subscription, invalidating the "subscriptions" tag. This action causes the cache to become stale for all users, leading to unnecessary data refetching.

A potential solution is to include the user ID in the cache tag (e.g., "subscriptions/<user_id>"), but this raises concerns about cache management and data clearing on the Next.js server. Specifically:

- How efficiently can Next.js handle numerous user-specific cache tags?
- Is it possible to combine tag-based and time-based revalidation for optimal performance?

I'm eager to hear your thoughts and suggestions on managing cache for user-specific data in Next.js, particularly concerning scalability and efficiency.

Thank you!