Ordinarily, yes, you'd need to include the other table...but now, the resource_params table has a foreign key relationship (with on delete cascade) to rows in the cache table. So once those go, the stuff in resource_params will get cleaned up.

It's a minor increase in time taken (looks like < 5% in my testing)...that's likely because for several rows in resource_params that make up a single resource, it's only a single row in resource_params_cache. And it's indexed, so finding it and nuking it is really fast.