Heterogeneous database system
A heterogeneous database system is an automated (or semi-automated) system for the integration of heterogeneous, disparate database management systems to present a user with a single, unified query interface.
Problems of heterogeneous database integration
Data model heterogeneity
Different ways of representing and storing the same data. Table decompositions may vary, column names (data labels) may be different (but have the same semantics), data encoding schemes may vary (i.e., should a measurement scale be explicitly included in a field or should it be implied elsewhere). Also referred as schematic heterogeneity.
Data across constituent databases may be related but different. Perhaps a database system must be able to integrate genomic and proteomic data. They are related—a gene may have several protein products—but the data are different (nucleotide sequences and amino acid sequences, or hydrophilic or -phobic amino acid sequence and positively or negatively charged amino acids). There may be many ways of looking at semantically similar, but distinct, datasets.
The system may also be required to present "new" knowledge to the user. Relationships may be inferred between data according to rules specified in domain ontologies.
- Sujansky, Walter (August 2001). "Heterogeneous Database Integration in Biomedicine". Journal of Biomedical Informatics. 34 (4): 285–298. doi:10.1006/jbin.2001.1024. Retrieved 30 July 2012.
- Sheth, Amit P.; James A. Larson (September 1990). "Federated Database Systems for Managing Distributed, Heterogeneous, and Autonomous Databases" (PDF). ACM Computing Surveys. 22 (3): 183–236. doi:10.1145/96602.96604.