A dynamic granularity locking protocol for tree-structured databases

A dynamic granularity locking protocol for tree-structured databases is presented. It is a variant of multi-granularity locking protocol which takes the system load condition and the conflict status of the transactions into an account while locking a data granule. It shares the advantages exhibited by both coarse and fine granularity locking protocols, and retains the power of multi-granularity locking protocol. It dynamically changes the granule size of the data to be locked depending upon both the transaction-requirement and the current system load. The strategy of the protocol is to lock coarse granules at light system load or when transaction conflicts are less, and to lock fine granules at heavy system load or when the conflicts are more. The protocol uses strict two phase locking, in conjunction, to ensure serializability. A simulation study has also been done to study the performance of the proposed protocol