SchemaSQL - A Language for Interoperability in Relational Multi-Database Systems

We provide a principled extension of SQL, called SchemaSQL , that offers the capability of uniform manipulation of data and meta-data in relational multi-database systems. We develop a precise syntax and semantics of SchemaSQL in a manner that extends traditional SQL syntax and semantics, and demonstrate the following. (1) SchemaSQL retains the flavour of SQL while supporting querying of both data and meta-data. (2) It can be used to represent data in a database in a structure substantially different from original database, in which data and meta-data may be interchanged. (3) It also permits the creation of views whose schema is dynamically dependent on the contents of the input instance. (4) While aggregation in SQL is restricted to values occurring in one column at a time, SchemaSQL permits “horizontal” aggregation and even aggregation over more general “blocks” of information. (5) SchemaSQL provides a great facility for interoperability and data/meta-data management in relational multi-database systems. We provide many examples to illustrate our claims. We outline an architecture for the implementation of SchemaSQL and discuss implementation algorithms based on available database technology that allows for powerful integration of SQL based relational DBMS. l This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC), the National Science Foundation (NSF), and The University of North Carolina at Greensboro. t Dept of Computer Science, Concordia University, Montreal, Canada. {laks,subbu}Ocs.concordia.ca $ Dept of Mathematical Sciences, University of North Carolina, Greensboro, NC. [email protected] Permission to copy without fee all or port of this material is gmnted provided that the copies ore not, mode or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its dote appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires o fee and/or special permission from the Endowment. Proceedings of the 22nd VLDB Conference Mumbai(Bombay), India, 1996