The design and implementation of multiple buffer cache in PostgreSQL

At present, the database management system occupies an important position in various application systems and in commercial systems. The study of database management system is attracting attention. We focus on open-source PostgreSQL comprising the function that it is not inferior to commercial database management system. But, there is the problem of the memory management in PostgreSQL. In a memory management method of PostgreSQL, the cache hit rate drops down under a specific condition. For example, when a transient large-scale search happens, most data including high frequency hit rate is flooded out of the buffer cache. And it causes the cache hit rate fall. It is thought that the buffer relocation method of current PostgreSQL is inefficient. To solve this problem, we suggest a multiple buffer cache method. The method is to divide the buffer cache into a plural number, and each buffer cache is managed individually according to the kind of data bound to each buffer cache. This can prevent the fall of the cache hit rate when a transient large-scale search happened.