A High Efficiency Approach to Querying Rough Data

Any attribute in rough relational database (RRDB) can be multi-valued, and has an indiscernibility relation in its domain. Currently, the research on rough data querying mainly discussed some simple select-querying. That is, selecting the tuples whose attribute´s value is equal to a constant from a single table. The main idea of its implementation is to expand the original search conditions according to the indiscernibility relation in attribute´s domain. Because the search conditions after being expanded need more calculation, the querying becomes very slow. In this paper, we present a solution called rough data querying based on encoding. Firstly encode the data of multi-valued attribute into the single-valued data according to the indiscernibility relation in attribute´s domain, and then execute the querying on the single-valued data despite the indiscernibility relation to make the implementation of rough data querying much simpler and more efficient.