We are batch processing. I don't know why you assume we aren't. FK constraints are simply too much burden for us. I'm not the OP, however, my company has experienced the performance headaches of FKs.

I didn't assume anything about you; I said OP uses a framework that (as far as I know) makes it difficult to batch requests, so they're probably not batching requests. And they mention doing a `before_create` hook, which again suggests they're operating on individual models. If you're already batching and still running into a wall, then yeah you might need to remove constraint validation or shard. But batching alone can probably take most people far past the scale they'll ever see.