Evaluating aggregate operations over imprecise data
- 1 April 1996
- journal article
- research article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Knowledge and Data Engineering
- Vol. 8 (2) , 273-284
- https://doi.org/10.1109/69.494166
Abstract
Imprecise data in databases were originally denoted as null values, which represent the meaning of ''values unknown at present.'' More generally, a partial value corresponds to a finite set of possible values for an attribute in which exactly one of the values is the ''true'' value. In this paper, we define a set of extended aggregate operations, namely sum, average, count, maximum, and minimum, which can be applied to an attribute containing partial values. Two types of aggregate operators are considered: scalar aggregates and aggregate functions. We study the properties of the aggregate operations and develop efficient algorithms for count, maximum and minimum. However, for sum and average, we point out that in general it takes exponential time complexity to do the computations.Keywords
This publication has 11 references indexed in Scilit:
- Evaluation of closely coupled systems for high performance database processingPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2002
- Performance modelling and comparisons of global shared buffer management policies in a cluster environmentIEEE Transactions on Computers, 1994
- Empirical performance evaluation of concurrency and coherency control protocols for database sharing systemsACM Transactions on Database Systems, 1993
- ARIESACM Transactions on Database Systems, 1992
- Cache consistency and concurrency control in a client/server DBMS architecturePublished by Association for Computing Machinery (ACM) ,1991
- Data caching tradeoffs in client-server DBMS architecturesPublished by Association for Computing Machinery (ACM) ,1991
- On coupling multi-systems through data sharingProceedings of the IEEE, 1987
- IBM Database 2 overviewIBM Systems Journal, 1984
- Locking granularity revisitedACM Transactions on Database Systems, 1979
- On Representatives of SubsetsJournal of the London Mathematical Society, 1935