关键词: 内存维表, 连接消除技术, 多入口维表访问技术, 顺序相关存储结构

Abstract: On analysis of database techniques facing advanced hardware, a novel optimization technique in multi-join operation based on main-memory storage model is proposed which stores dimensional tables in main-memory. By serializing primary keys of dimensional tables, the primary keys are equal to offset values of main-memory dimensional tuples, so dimensional tuples can be directly accessed by start address of dimensional table plus offset value. Further optimization is proposed by decomposing dimensional tables into main-memory column structures with single or several fields of dimensional table in order to reduce tuple width for better cache performance. In experiments, simulating algorithms of traditional query plan of SQL Server 2005, join index algorithm and optimized column model join algorithm are compared for performance analysis. The results show that multi-join operation based on main-memory storage model algorithm has better performance in processing complex queries in star-schema data warehouse with multiple predicates and multiple join operations. Compared with join index algorithm, the perform-ance is equal and no additional space cost is needed. Compared with column storage model, this algorithm has better compatibility and performance, and it can also be implemented in traditional disk resident database systems.

Key words: memory dimensional table, join elimination technique, multi-entry dimensional table accessing technique, sequence conscious storage structure