The VAGUE system, described in this paper, is designed to support imprecise
(vague) queries on a relational database system. The objective is to be able
to answer queries such as "List all inexpensive French restaurants that are
located downtown," where the requirements for inexpensive, downtown, and
even French may provide fuzzy matches to the exact data stored in a restaurant
database. The author presents an interesting and practical approach for
designing and querying a relational database to accommodate such vague queries
directly. The concept of "vagueness" is implemented in the system by
using a data metric on the distance between values in attribute domains. A
database designer must invent and build a distance metric for each attribute
based on the semantics of database applications. Each distance metric is
represented in the database in one of four ways; using a built-in metric
function, providing a procedure to compute the metric, designing a separate
relation to store the metric, or using a reference relation where the
attribute distance is based on the distance metrics of related attributes. The
QUEL query language is extended to include a "similar-to" operator that
requires the use of the distance metrics in determining a query result. In
addition, the VAGUE system provides a user interface that prompts the user to
help formulate the query and understand the meaning of its results. This
well-written paper demonstrates the merits of the author's approach. The
related research areas of fuzzy database, similarity in information retrieval,
database browsers, and ambiguity in query languages are surveyed and their
relationship to the current research is shown. I recommend this paper to
anyone who is interested in these topics.
<p>
Alan Raymond Hevner<br>
<em>ACM Computing Reviews</em>