Locking performance in a shared nothing parallel database machine

A quantitative performance study of two-phase locking in a parallel database machine using a simulation-based methodology is described. The DBSIM simulation methodology uses models at two levels: a Petri net model at the higher level and a queuing network model at the lower level. The Petri net model captures the characteristics of parallelism and synchronization at the workload level, while the queuing network model captures queuing aspects of the system at the physical resource level. Transactions in a workload are specified using a performance-oriented specification language based on the transaction component graph, a data flow graph with database operators. The transaction specifications are translated into Petri net representations to derive the simulation experiments. The workload is a transaction taken from an order-entry application. A shared-nothing parallel machine architecture is assumed. Results of analysis of a two-phase locking strategy with machine sizes ranging from 4 to 256 processors are presented