The two most abused relays in terms of spam are Damus and Nostr.bg. I’m finding perhaps 30%+ of total DB events can be purged. And the current load of inserts drops by 75% with spam filtering.
It’s a moving target, but relays need to protect themselves from malicious actors. My DB is already 40Gb including indexes.
I’ll keep sharing any spam preventing approaches I find that work. ML is currently the best approach.