Concurrent operations in linear hashing

New concurrent operations for linear hashing are presented. The algorithm uses an optimistic concurrency control technique which leads an operation to “retry” when interaction among concurrent conflicting operations occurs. The method is unique in that it makes use of a strictly increasing counter to filter out a significant portion of unnecessary retries, thus allowing search, insert, and delete operations to proceed concurrently with split and merge operations. The search operation does not need to set any lock, and no operation needs to set lock on shared directory variables, such as the pointer to the next bucket to split, thus enabling a higher degree of interleaving in the system. An argument for correctness, in terms of a correctness criterion which incorporates external consistency, is presented, as well as a discussion of the filter performance.