Hybrid concurrency control for mobile computing

In this paper, we propose a hybrid concurrency control scheme which can alleviate effects of frequent disconnections and limitation of bandwidth in mobile computing environments. If a transaction in a mobile host executes only read operations, our concurrency control scheme is the same as the optimistic concurrency control scheme based on timestamp history. Otherwise, if it executes write operations, the write set has to be sent to a fixed host during the execution phase. If a disconnection with the mobile host occurs, the fixed host performs a pre-validation of the write set. As a result of this pre-validation, if conflicts are detected, the transaction is aborted. Otherwise, we use the locking method which is called weak lock. Our scheme will reduce number of aborts and validation time without message overheads.