Uncertain database
An uncertain database[1] is a kind of database where the uncertainty in the information contained is explicitly represented and managed, usually in a compact way.
At the basis of uncertain database is the notion of possible world: a possible world of an uncertain database is a (certain) database which is one of the possible realization of the uncertain database. A given uncertain database typically has more than one, and potentially infinitely many, possible worlds.
Uncertain database models differ in how they represent and quantify these possible worlds:
- Incomplete databases[2] are a compact representation of the set of possible worlds – the use of NULL in SQL, arguably the most commonplace instantiation of uncertain databases, is an example of incomplete database model.
- Probabilistic databases[3] are a compact representation of a probability distribution over the set of possible worlds.
- Fuzzy databases[4] are a compact representation of a fuzzy set of the possible worlds.
Though mostly studied in the relational setting, uncertain database models can also be defined in other relational models such as graph databases[5] or XML databases.
References
- ^ Aggarwal, Charu C., ed. (2009). "Managing and Mining Uncertain Data". Advances in Database Systems. doi:10.1007/978-0-387-09690-2. ISSN 1386-2944.
- ^ Imieliński, Tomasz; Lipski, Witold (1984-09-20). "Incomplete Information in Relational Databases". Journal of the ACM. 31 (4): 761–791. doi:10.1145/1634.1886. ISSN 0004-5411.}}
- ^ Suciu, Dan; Olteanu, Dan; Ré, Christopher; Koch, Christoph (2011). "Probabilistic Databases". Synthesis Lectures on Data Management. doi:10.1007/978-3-031-01879-4. ISSN 2153-5418.
- ^ Petry, Frederick E. (1996). "Fuzzy Databases". International Series in Intelligent Technologies. doi:10.1007/978-1-4613-1319-9. ISSN 1382-3434.
- ^ Khan, Arijit; Ye, Yuan; Chen, Lei (2018). "On Uncertain Graphs". Synthesis Lectures on Data Management. doi:10.1007/978-3-031-01860-2. ISSN 2153-5418.