@zvava@twtxt.net I might misunderstand what you wrote, but only hashing the message once and storing the hash together with the message in the database seems a way better approch to me. It’s fixed and doesn’t change, so there’s no need to recompute it during runtime over and over and over again. You just have it. And can easily look up other messages by hash.
@zvava@twtxt.net The problem you now then is you lose integrity of the message content if you compute the hashes at runtime rather than on the way in. So if your message content or database becomes corrupt in any way, so do your hashes.