The response time distribution in a real-time database with optimistic concurrency control

For a real-time shared-memory database with optimistic concurrency control, an approximation for the transaction response time distribution is obtained. The model assumes that transactions arrive at the database according to a Poisson process, that every transaction uses an equal number of dat.a-items uniformly chosen, and that the multiprogramming level is bounded. The analysis is based on a decomposit.ion approach: results for the closed system wit.h a fixed llumber of transactions are used t.o derive the response time distribution ill the open system with Poisson arrivals. Numerical experiments that compare the analysis with simulation indicate t.hat the approximation for the response time distribution works well for the dosed system. For the open system the approximation is useful if the load is not too high.