When to use ETS and Map?

[sasajuric]

@rupurt

I replaced my Map based order book with an ETS ordered set implementation and the difference in performance is huge.

You’re using ordered set which is relatively slow compared to other types. Could you use regular set? Also if the table is accessed from other processes, provide the read_concurrency: true option (but in your case you don’t need write_concurrency, b/c the table is protected, so it’s written to from a single process.

@rupurt

I would also love to know the answer to this!!

You already answered it yourself:

@rupurt

I’d like to be able to configure the different order book implementations so that I can benchmark them together easily

So basically, measure twice, cut once

@dimitarvp

That being said, if you have to reach for ETS then I’d say that it’s possible that you might also be better served by a native map structure implemented in Rust; integrating that with Elixir (with rustler ) is quite easy.

Can you elaborate why? I’d be surprised if that solution would be significantly faster than ETS, if faster at all, b/c I think (but not completely sure) that the same limitations apply (data still has to be copied in/out).