Cache smearing seems like it would suffer from the obvious problem of invalidation. The solution they come up with is rather than having a piece of data associated with one cache key "foo" it is associated with "foo0, foo1, foo.., foo8".<p>If you have one key you can just delete it, but now you have to do that on all the possible versions of the key.<p>(Of course if they're relying upon TTL settings for expiration then this doesn't matter.)