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VLDB Journal,4, 45-86 (1995), Ron Sacks-Davis, Editor
45
QVLDB
HyperFile: A Data and Query Model for Documents
Chris Clifton, Hector Garcia-Molina, and David Bloom
Received July 1, 1992; revised version received, January 25, 1994; accepted October 7,
1994.
Abstract. Non-quantitative information such as documents and pictures pose in-
teresting new problems in the database world. Traditional data models and query
languages do not provide appropriate support for this information. Such data are
typically stored in file systems, which do not provide the security, integrity, or query
features of database management systems. The hypertext model has emerged as
a good interface to this information; however, finding information using hypertext
browsing does not scale well. We developed a query interface that serves as an extension of the browsing model of hypertext systems. These queries minimize the
repeated user interactions required to locate data in a standard hypertext system.
HyperFile is a prototype data server interface. In this article, we describe HyperFile, including a number of issues such as query generation, query processing, and
indexing.
Key Words. Hypertext, indexing, user interface.
1. Introduction
Hypertext (Conklin, 1987) is emerging as a model for the m a n a g e m e n t o f looselystructured information. T h e key idea is to view data as a collection of "cards" or
nodes that are linked in a variety of ways. E a c h n o d e may contain text or multimedia
information. E n d users can view one or m o r e cards at a time, and can traverse
links to view other nodes.
Hypertext systems are currently built on top of file-based storage systems. This
means that they often do not provide adequate data m a n a g e m e n t facilities such as
indexing, concurrency control, and recovery. Storage systems for h y p e r m e d i a must
provide these facilities (Halasz, 1988; Lange, 1992; Grelnbaek, 1994). To add data
Chris Clifton, Ph.D., is Assistant Professor, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208-3118, [email protected], Hector Garcia-Molina,
Ph.D., is Professor, Department of Computer Science, Stanford University, Stanford, CA 94305-2140, [email protected], and David Bloom, B.S., is with Anderson Consulting, 1345 Avenue of the Americas,
Room 928, New York, NY 10105.