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Paper: The StarView Flexible Query Mechanism
Volume: 61, Astronomical Data Analysis Software and Systems III
Page: 92
Authors: Silberberg, D. P.; Semmel, R. D.
Abstract: We are developing a distributed user interface to the Space Telescope Data Archive and Distribution Service (DADS) known as StarView. The DADS architecture consists of the data archive as well as a relational database catalog describing the archived data. Users query the DADS catalog via StarView forms. Based on the results, users decide which data sets to retrieve from the DADS archive. Archive requests are packaged by StarView and sent to DADS, which returns the requested data sets to the users. The DADS catalog is comprised of more than 1500 columns, or keywords, distributed among 50 tables. StarView has several defined forms to serve as the interface for the most common catalog queries. In a simple implementation, the form definitions associate each field with a corresponding keyword and table, and associate each form with a corresponding join of database tables. However, the predefined forms represent only a small subset of the keyword combinations that users need for querying the catalog. As StarView services a wide and diverse group of users, the interface must provide the flexibility to query the catalog by the combination of keywords that best suits a user's needs. Moreover, users should not be required to understand the topology of the database when formulating queries involving joins. StarView provides the needed flexibility by enabling users to view the columns of the DADS catalog as if they were defined in a single table known as a Universal Relation (UR). In the UR approach, users need only specify keywords of interest, and the interface software infers the underlying joins for the corresponding query. This paper describes the challenges of providing flexible user interfaces for databases with many interrelated tables. In addition to providing a more detailed description of the problem, inherent difficulties in interface development are discussed and the solution adopted in StarView is presented.
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