Locking and Latching in a Memory-Resident Database System

As part of the Starburst extensible database project developed at the IBM Almaden Research Center, we designed and implemented a memory-resident storage component that co-exists with Star-burst’s diskoriented storage component. The two storage components share the same common services, such as query optimization, transaction management, etc. However, the memory-resident storage component is faster than the disk-oriented storage component and hence needs faster run-time services. This paper examines two runtime services, the lock manager and the latch mechanism, and investigates possible cost-cutting measures. We propose the use of of a single latch for protecting a table, all of its indexes, and all of its related lock information, in order to reduce storage component latch costs. VVe then show that although a table-level latch is a large granule latch, it does not significantly restrict concurrency. VVe also examine traditional lock manager design and suggest a different design that is appropriate for memory-resident storage components. The new design exploits direct addressing of lock data and dynamic, multi-granularity locks. Performance measurements of the new lock manager show that it outperforms the regular Starburst lock manager, which is of a traditional lock manager design, by as much as