Hash Indexes
Hash indexes are a type of database index that uses a hash function to map keys to specific locations in memory or storage, enabling fast exact-match lookups. They are particularly efficient for equality queries, such as finding a record by its primary key, but are not suitable for range queries or sorting operations. This indexing method is commonly implemented in in-memory databases and some disk-based systems for optimized key-value access.
Developers should use hash indexes when they need to perform frequent exact-match searches, such as retrieving user data by a unique ID or looking up cached values, as they offer O(1) average time complexity for these operations. They are ideal for applications with high read performance requirements for specific keys, like session management or real-time analytics, but should be avoided for queries involving ranges, partial matches, or ordered data retrieval.