The Response-Time Distribution in a Real-Time Database with Optimistic Concurrency Control and Exponential Execution Times

摘要

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 takes an exponential execution time and uses an equal number of data-items uniformly chosen, and that the multprogramming level is bounded. The analysis is based on a decomposition approach: results for the closed system with a fixed number of transactions are used to derive the response-time distribution in the open system with Poisson arrivals. Numerical experiments that compare analysis with simulation indicate that the approximation for the throughput and the response-time distribution works well for the closed system. For the open system the approximation for the response-time distribution is useful if the load is not too high.