What level of complexity can be considered for hash indexes?

Hash indexes typically provide an average access time to an element of around O(1), meaning constant time. This is achieved by computing a hash function that directly points to the data's position. However, in the worst case, such as in collisions, the complexity can degrade to O(n), where n is the number of elements in the hash table. In practice, with a good hash function and proper collision resolution, the complexity remains close to O(1).