Query language support for incomplete information in the MayBMS system

MayBMS [4, 1, 3, 2] is a data management system for incomplete information developed at Saarland University. Its main features are a simple and compact representation system for incomplete information and a language called I-SQL with explicit operations for handling uncertainty. MayBMS is currently an extension of PostgreSQL and manages both complete and incomplete data and evaluates I-SQL queries. The focus of the demonstration is I-SQL. I-SQL is a natural extension of SQL to the context of incomplete information. Like SQL, I-SQL is a generic language in that it preserves the independence of the data from its representation. Thus the answers to I-SQL queries do not depend on details of how the data is stored. I-SQL proves expressive enough for a variety of application scenarios, where incompleteness is ubiquitous: planning, design, business decisionmaking, data cleaning [2], and, as exemplified in Section 3, monitoring moving objects when only partial information is available, like satellite tracking of whales. Differently from SQL, I-SQL has explicit operations for dealing with uncertainty. Extensions of SQL with limited operations like certain, which closes the possible worlds semantics and computes the certain answers, are not expressive enough, as they do not allow for the convenient construction of new worlds or for a uniform transformation of both complete and incomplete databases. The present demonstration reconfirms that explicit language constructs that deal with uncertainty are definitely useful and even mandatory in many application scenarios where incompleteness is commonplace.