# Overview An indexing method that keeps all keys in memory in a [[Hash Table]] with their corresponding addresses on disk. # Key Considerations In the words of database expert Bruce Momjian: "Hash indexes solve a problem we rarely have." # Pros of Hash Index #flashcard - O(1) reads and O(1) writes <!--ID: 1751507776888--> # Cons of Hash Index #flashcard - Keys need to fit in-memory, which has issues with size, cost, and durability. - Poor support for range queries <!--ID: 1751507776890--> # Use Cases - You need the fastest possible exact-match lookups - You'll never need range queries - You have plenty of memory # Related Topics