PreCN: Preprocessing Candidate Networks for Efficient Keyword Search over Databases

Keyword Search Over Relational Databases(KSORD) has attracted much research interest since casual users or Web users can use the techniques to easily access databases through free-form keyword queries, just like searching the Web. However, it is a critical issue that how to improve the performance of KSORD systems. In this paper, we focus on the performance improvement of schema-graph-based online KSORD systems and propose a novel Preprocessing Candidate Network(PreCN) approach to support efficient keyword search over relational databases. Based on a given database schema, PreCN reduces CN generation time by preprocessing the maximum Tuple Sets Graph(Gts) to generate CNs in advance and to store them in the database. When a user query comes, its CNs will be quickly retrieved from the database instead of being temporarily generated through a breadth-first traversal of its Gts. Extensive experiments show that the approach PreCN is efficient and effective.