Scheduling Algorithm for the Reuse Buffers in Column-Store Data Warehouse Query Execution

Reusing intermediates is an important way to improve the performance of query execution. The current column-store systems mainly focus on the reusage of the intermediates in multiple query plans, while large quantities of reusable intermediates in a single query are neglected. The intermediates of a single query are suitable for reusing during the process of execution due to the characteristics of their high certainty and the evaluable amount. To deal with this problem, a novel scheduling algorithm for the reuse buffers is proposed. Firstly, we propose a reusability estimation model based on the relative position of the given operator node in the physical execution tree as well as the estimated volume of the intermediates it produces during execution. Then, we provide the reuse buffer scheduling algorithm based on the results of the reusability estimation model. In the process of query execution for each query plan, the scheduling algorithm is executed on the basis of the results of its reusability estimation model, making the more important intermediates stay longer in the memory than the others, leading the improvement of query performance. The experimental results on the benchmark data set SSB verify the effectiveness of the proposed method.