SGER: Managing Hierarchically Organized Data in Modern Databases

层次数据库在30年前是标准的，但自那以后已经完全被关系数据库所取代，尽管层次结构仍然是我们在其他领域组织信息的最常见方式。本研究项目的目标是根据数据库技术的进步重新评价分层数据库。本文的论点是，关系数据库取代了层次数据库，不是因为平面关系提供了更好的数据组织，而是因为关系技术提供了其他重要的好处，即数据组织与应用程序逻辑的分离以及声明性查询语言的概念。本项目中的方法是首先将LDAP（轻量级目录访问协议）作为基本的分层数据库，然后对其进行扩展以提供成熟的数据库功能。这个项目的结果将证明构建一个层次数据库的可行性和价值，它是一种比目前流行的关系数据库更加灵活和可扩展的结构。http://www.eecs.umich.edu/~jag/

Hierarchical databases were standard thirty years ago, but have been completely supplanted by relational databases since, in spite of hierarchy remaining the most common way in which we organize information in other spheres. The goal of this research project is to re-evaluate hierarchical databases in the light of the progress made in database technology. The thesis is that relational databases supplanted hierarchical databases not because flat relations provided a superior organization of the data, but rather on account of other crucial benefits relational technology provided, namely the separation of data organization from application logic and the notion of a declarative query language. The approach in this project is to begin with LDAP (Lightweight Directory Access Protocol) as a rudimentary hierarchical database, and to extend it to provide full-fledged database functionality. The results of this project will demonstrate the feasibility and value of building a hierarchical database as a far more flexible and scalable structure than the relational databases that are prevalent today. http://www.eecs.umich.edu/~jag/