The first time I heard of bloom filters was back when I worked at Google a decade ago (on the search indexing team). We used them in MapReduces when doing cross

The first time I heard of bloom filters was back when I worked at Google a decade ago (on the search indexing team). We used them in MapReduces when doing cross-machine table lookups. The idea was to load the bloom filters into memory on the machines doing the lookups and then to only do the lookup if the bloom filter test passed - this optimization worked because a large fraction of the lookups were for entries not contained in the tables. I can't actually remember what data was being looked up in the tables, though.