1Practical Response Time Estimation in Parallel Relational Database Systems

Abstract — An analytical approach to response time estimation in parallel relational database systems has been developed. It is based on a representation of database activity, in which queries are mapped to low-level patterns of resource consumption, capturing the execution logic of relational operators and mechanisms such as pipelined and partitioned execution. Resource usage profiles are mapped to open multi-class queueing networks. Queue waiting times are estimated using a heuristic rule, which labels resources as M/M/1 or M/G/1 queues. From these and the resource usage profile the average response time of a query is obtained. Synchronisation mechanisms such as pipelines between operators and partitioned parallelism are taken into account. The results of the analytical approach are compared against measurements of Informix XPS performance on a parallel system. Index Terms — performance estimation, analytical model, queueing networks, pipeline parallelism, validation.