Yes.
Redis can give you an atomic, cross‑node count while users join and leave in real time. It won’t match ETS’s raw speed, but building your own synchronization and network‑transfer logic for ETS updates erodes that advantage. At high join/leave volumes, custom distribution code risks race conditions and latency that Redis’s built‑in counters avoid.
You will never get 100%, always correct counts when dealing with hundreds of thousands of users connecting at the same time, but at least with Redis the results will be atomically consistent.
No.
ETS is local, it will always be faster than using an external source.
However, I should also add that although ETS is faster locally you still presumably have to manually process users/counts and send info between nodes. Your custom data distribution logic will not magically be done in an instant, especially at the scale of hundreds of thousands of users constantly joining and leaving.
I should add, your posts “problem” is the below. You have only mentioned speed whilst trying to counter Redis, but I recommended Redis because it answers your posts problem. You’ve changed the argument from “I can’t get the counts correct” to “but it’s gotta be fast”.
I’m not going to reply any further, as I feel I’ve expressed my opinion multiple times at this point and it would be a waste of time for me to continue to push a tool you obviously have no interest in using.
Apologies if I’ve annoyed you by turning this into ETS vs Redis, but I still maintain Redis is the correct tool for the job for track user presence with atomic room counts.
