A Universal-Scheme Approach to Statistical Databases Containing Homogeneous Summary Tables

Abstract

In many situations a statistical database contains multiple summary tables, which report summary statistics on the same summary variable for the same population of individuals or objects using different classification criteria (�homogeneous� summary tables) Existing query languages consider only those queries which may aggregate data stored in a single summary table When a statistical database contains homogeneous summary tables, such query languages do not allow an integrated view of data, whereas statistic] ans are inclined to view and query a collection of homogeneous summary tables as if they were actually a single higher-dimensional summary table This le@imizes the search for a universal-scheme solution to the problem of data integration m such statistical databases. It is shown that such a solution can be found if the database tables contain additive summary data. Accordingly, queries are grouped into three classes: queries that can be evaluated to single values (evatuabte queries): queries that can be evaluated to value ranges (ansu,erable querkes); and queries whose values remain unknown (unansu,erable querzes). The membership of a given query to one of these three classes us not an intrinsic property of the query, but depends on both the type of the summary variable and tbe dependencies that are assumed in the universal scheme by the database designer On the basis of such information, linear-time procedures for recogmzing and answering answerable and evaluable queries are developed. © 1993, ACM. All rights reserved.