Abstract: DB Trichotomy, an optimized method of database design, comes from real estate infomaion system development. According to this method, temporary DB、formal DB and history DB are defined, just because the same object has different status in management workflow. This paper tries to answer the why、what and how about DB trichotomy. This method can accelerate the DB operation and keep the data from being destructed. This method has been used in Hangzhou real estate information system.

Key words: DB trichotomy; Real estate information system; Formal DB; Temporary DB; History DB

摘要： 三库分离技术是在房产信息系统数据库设计实践中提出的一种实用的数据库优化技术。它是在数据库物理设计中将同一对象的不同生命周期在数据库中划分为正式库、工作库、历史库。该文分析了三库分离技术的应用背景、定义及相应的数据库设计方法，并总结了其在效率和保证数据安全性方面的优点和应用原则。最后还介绍了三库分离技术在杭州市房产管理信息系统中的实际应用情况。

关键词: 三库分离技术；房产信息系统；正式库；工作库；历史库