It depends how you implement your hash-table, for example I've done something similar using cuckoo hashing: https://github.com/pik/time-rotated-cache-filter htt

It depends how you implement your hash-table, for example I've done something similar using cuckoo hashing: https://github.com/pik/time-rotated-cache-filter https://github.com/pik/time-rotated-cache-filter > It seems to me that if you're looking for "the opposite of a bloom filter", you're probably wanting those properties. You can't really get a theoretical opposite of a bloom-filter unless you store the entries verbatim, since any hash/compression introduces the chance of collisions meaning you can only provide probabilistic guarantees where as a bloom-filter gives a strong guarantee.