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 presented. The DBSIM simulation methodology uses 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 drive the simulation experiments. Results of an analysis of a two-phase locking strategy with machine sizes ranging from 4 to 256 processors are presented