Optimal buffer allocation in a multi-query environment

Abstract

The concepts of memory consumption and return on consumption (ROC) are used as the basis of memory allocations. A global optimization strategy using simulated annealing is developed which minimizes the average response time over all queries under the constraint that the total memory consumption rate has to be less than the buffer size. It selects the optimal join method and memory allocation for all queries simultaneously. By analyzing the way that the optimal strategy makes memory allocations, a heuristic threshold strategy is proposed. The threshold strategy is based on the concept of ROC. As the memory consumption rate by all queries is limited by the buffer size, the strategy tries to allocate the memory so as to make sure that a certain level of ROC is achieved. A simulation model is developed to demonstrate that the heuristic strategy yields performance that is very close to the optimal strategy and is far superior to the conventional allocation strategy.