[romange]

Backward compatibility is good? I disagree with you regarding this specific case. Redis philosophy is to add more and more settings, requiring from an end-user to understand internals and low-level trade-offs. And I am sorry, but in the case of caching use-case, a user wants it to "just work" and it's a reasonable expectation. I've run Redis myself in a startup I worked at - I tried LRU, LFU and it did not work very well due to mixed traffic patterns. And I even did not know if it did not work well due to LFU/LRU heuristic or due to the fact that Redis does random sampling and evicts a small number of items it tests. Eventually, I gave up and moved on. I am sure most users do the same or try increasing its cache capacity to ridiculous sizes.

So yeah, I do not completely ignore Redis LFU, I just did not find useful to mention it because from my experience, Redis LFU is not being widely used, and does not have significant advantage over Redis LRU (if at all) and I wanted to maintain the focus and keep my post succinct and clear.

I also have not provided any benchmarks in the post, not because I have something to hide, just because I do not have an easy setup to benchmark cache efficiency vs Redis and I do not have time to invest into it right now.

Back then when I developed DashCache, I used Caffeine simulator to compare it to dozens other heuristics implemented in Caffeine using real-world data (twitter traces) and it was better than most of then (including LFU). It lost to algorithms that keep some information about evicted items (like TinyLFU or its extensions).