Let's talk about cache invalidation strategies.

hey everyone, ive been thinking a lot about cache invalidation lately. its one of those things that seems simple until you hit edge cases. weve been using TTL-based invalidation for a lot of our read-heavy data, but it feels a bit blunt. what strategies have you found most effective, especially for data that changes frequently but not constantly? thinking about things like write-through, write-behind, or even event-driven invalidation. what are the trade-offs youve seen in production?