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Chapter II: Databases & Data Modeling

Bloom Filters

A probabilistic structure that tests set membership with no false negatives.

In short

A Bloom filter is a space-efficient probabilistic structure that answers "is this item in the set?" with no false negatives.

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Key takeaways

  • No false negatives, but possible false positives.
  • Great as a cheap pre-check before an expensive lookup.
  • Standard Bloom filters support insert and query, not delete.