[zkhalique]

Caching is the classic memory-time tradeoff, everything from memoizing a function, to DNS caching, to storing a web resource that didn't change.

I think that, if a cache is combined with a push indicating a change, then it's basically a local "eventually consistent replica" which catches up as soon as there is a connection to the source of truth.

Seriously, many times you are READING data which changes rarely (read: every X minutes / hours / days). So, in the meantime, every code path that will need access to the data may as well look in the local snapshot first.

The question about consistency is an interesting one. The client's view of the authoritative server state may be slightly out of date, when the user issues a request. If certain events happened in the meantime that affect the user's view, then the action can just be kicked back to the user, to be resolved. But 90%+ of the time, the view depends on 10 things that "change rarely", so a cache is a great improvement.

Related issues involve batching / throttling / waiting for already-sent requests to complete.

PS: That was quick. I posted this and literally 10 seconds later it got a downvote.