Subbins

A subbin is a concept found in computer science, specifically within the realm of data structures and algorithms, most notably in hash tables. In a hash table, data is stored in arrays or lists called bins. When multiple keys hash to the same index in the hash table, a collision occurs. Subbins are a way to manage these collisions more efficiently than simple linked lists.

Instead of using a single linked list for each bin, a subbin approach divides each primary bin into smaller, more manageable sub-bins. When a collision occurs within a primary bin, the new item is placed into one of its associated sub-bins. This strategy can improve performance by reducing the average length of the lists that need to be traversed during search, insertion, or deletion operations.

The effectiveness of subbins depends on factors such as the hashing function, the size of the primary bins, and the number of sub-bins within each primary bin. A well-implemented subbin system can help maintain the near-constant time complexity that hash tables are known for, even with a significant number of collisions. The concept is a refinement of open addressing and separate chaining collision resolution techniques, aiming for a balance between space utilization and retrieval speed.