Bloom filters are probabilistic, meaning they don't always produce the right result. From the article you posted: > False positive matches are possible, but fa

Bloom filters are probabilistic, meaning they don't always produce the right result. From the article you posted: > False positive matches are possible, but false negatives are not – in other words, a query returns either "possibly in set" or "definitely not in set". Elements can be added to the set, but not removed (though this can be addressed with a "counting" filter); the more elements that are added to the set, the larger the probability of false positives. So I don't think they're the right choice for this problem, if you actually depend on the result "not here" vs "never was here" being right.