An enhanced concurrency control scheme for multi-dimensional index structures

Propose an enhanced concurrency control algorithm that minimizes the query delay efficiently. The factors that delay search operations and deteriorate the concurrency of index structures are node splits and minimum bounding region (MBR) updates in multi-dimensional index structures. In our algorithm, in order to reduce the query delay by splitting operations, we optimize the exclusive latching time on a split node. It does not hold exclusive latches throughout the whole split time but only during the physical node split time, which occupies only a small part of the whole split time. Also, to avoid the query delay caused by MBR updates, we introduce the partial lock coupling (PLC) technique. PLC increases concurrency by using lock coupling only in the case of MBR shrinking operations that are less frequent than MBR expansion operations. For performance evaluation, we implement the proposed algorithm and one of the existing link technique-based algorithms on MIDAS-III, which is the storage system of the BADA-III DBMS. We show, through various experiments, that our proposed algorithm outperforms the existing algorithm in terms of throughput and response time.