Hey there, author of the article here. Ben already gave very comprehensive answers, I’ll just add a few points as to when to use constant pools

1. Large data that needs to be read by a lot of processes. If it’s just a handful of processes, you might be better off with ETS or something else, unless the data is gigantically large
2. Data that still needs to be updated regularly, but infrequently compared to the reads

I should note that compilation of a module with static data is actually deceptively fast especially if you use Module.create/3.

I should also point out that binary data benefits from reference counting. IIRC, if the binary is 64 bytes or greater only a reference to it is copied over to a process. Just another thing to possibly consider if it fits your needs.

I saw the mention of :persistent_term, so I’d like to underline that dynamically compiling modules with static data now that we have :persistent_term is in almost all of the scenarios going to be slower and will do more operations than using :persistent_term. I’d consider that technique to be largely obsolete now.

@Cruz There’s a final option here which is to treat the catalog like a file and put it on a CDN with appropriate cache headers. If it changes rarely and clients are of the type that can cache values locally then in an optimal world they shouldn’t even be reretrieving it all that often.