Range query estimation with data skewness for top-k retrieval

•This paper extends the query-mapping method for top-k retrieval in a relational DB.•Top-k retrieval finds a small set of approximate results for user specified values.•Query-mapping involves converting a top-k query into a range query.•Proposed method incorporates data skewness in cost-based query-mapping.•Experiments show improved efficiency and robustness across parameters.

Top-k querying can significantly improve the performance of web-based business intelligence applications such as price comparison and product recommendation systems. Top-k retrieval involves finding a limited number of records in a relational database that are most similar to user-specified attribute-value pairs. This paper extends the cost-based query-mapping method for top-k retrieval by incorporating data skewness in range estimation. Experiments on real world and synthetic multi-attribute data sets show that incorporating data skewness provides a robust performance across different types of data sets, query sets, distance functions, and histograms.