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Hyperfile, A Database Manager for Documents (Thesis)

Report ID:
May 1991
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Documents, pictures, and other such non-quantitative information pose
interesting new problems in the database world. Such data has
traditionally been stored in file systems, which do not provide the
security, integrity, or query features of database management systems.
We have developed HyperFile, a data server that provides query
facilities (as well as some other database features) while maintaining
the flexibility and efficiency of a file system. HyperFile is based on
the hypertext notion of free-form objects connected by links.
Hypertext systems "query" their database by browsing (reading objects
and following links.) We present a query interface that maintains much
of the flavor of browsing, allowing the user to specify a single query
rather than manually following links. This eliminates the repeated
user interactions of hypertext browsing, and allows the hypertext model
to be extended to larger and less structured databases. An algorithm
for processing HyperFile queries is presented. We also show how to
extend this algorithm for distributed query processing, and present
experimental results from a distributed HyperFile server. Another
issue explored is indexing. In HyperFile, searches are often
demarcated by pointers between items. Thus the scope of the search may
change dynamically, whereas traditional indexes cover a statically
defined region such as a relation. This demands new indexing
techniques. Some ideas on indexing in HyperFile are presented, as well
as experiments in a large HyperFile database. Also presented is a
sample HyperFile application. This is a "browser" that uses menus to
guide the user in constructing HyperFile queries.

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