Bloom Watch

A Bloom Filter (sometimes referred to as Bloom Watch) is a space-efficient data structure used to quickly test if an item is part of a set. It can tell you if an item definitely is not in the set or may be in the set, but it cannot confirm with 100% certainty if it is. It uses multiple hash functions to map items to positions in a fixed-length array of bits. If all relevant bits are set, the item might be in the set; if not, it definitely isn’t. Bloom Filters are useful for large-scale systems needing fast, memory-efficient membership queries with an acceptable false positive rate.