Progressive Keyword Search in Relational Databases

A common approach to performing keyword search over relational databases is to find the minimum Steiner trees in database graphs. These methods, however, are rather expensive as the minimum Steiner tree problem is known to be NP-hard. Further, these methods cannot benefit from DBMS capabilities. We propose a new concept called Compact Steiner Tree (CSTree), which can be used to approximate the Steiner tree problem for answering top-k keyword queries efficiently. We propose a structure-aware index, together with an effective ranking mechanism for fast, progressive and accurate retrieval of $top$-$k$ highest ranked CSTrees. The proposed techniques can be implemented using a standard RDBMS to benefit from its indexing and query processing capability. The experimental results show that our method achieves high search efficiency and result quality comparing to existing state-of-the-art approaches.