Tuple source relational model: A source-aware data model for multidatabases

In some integration projects, complete integration of database instances ma y not be necessary. It may also be too costly and impossible to do so due t o poor local data quality and insufficient instance-level knowledge. In thi s research, we study how multidatabases with global schemas should be repre sented and manipulated when the data instances from the local databases do not require to be fully integrated. We propose the tuple source (TS) relati onal model to represent multidatabases under such an integration requiremen t. This model extends the classical relational model by augmenting every re lation with a source attribute to identify the local database that the tupl es come from. The source attribute can also be used to specify the right co ntext to interpret global data instances. To manipulate TS relations, we ha ve developed a set of tuple source relational algebraic operations and an e xtended SQL query language known as TS-SQL. With TS relational model, flexi ble multidatabase queries that involve instances from different local datab ases can be formulated easily. In this paper, we also reported our distribu ted query processing and optimization strategies and their implementation. (C) 1999 Elsevier Science B.V. All rights reserved.