[superbobry]

I guess FM index is just not the right thing to use when you need a key-value data store. It's a full text index -- a data structure, which allows fast substring queries over a fixed text corpus.

[arethuza]

Perhaps if you want to store (tag) sub-strings with stored data then it might make sense?

[superbobry]

Yup, that might work, but still, this is a weird idea for a key-value store, maybe a DAWG or a radix tree would do better.