Efficient keyword based search over structured data

Keyword search is integrated in many applications on account of the convenience to convey users query intention, because the success of this research will relieve users from learning complex structure query languages and knowing the underlying schema of the queried data. Recently, answering keyword queries on both XML and graph data has drawn the attention of web and database communities. XML is the standard for data representation and exchange on the Internet. Graph also provides a common representation of relational database and network such as social network, traffic network. The universality of XML and graph representations makes them often be the natural choice when integrating data from different sources with various schemas. Supporting keyword queries on free structured and graph structured data is therefore fundamentally important. Furthermore, the rapid growth of user-generated content on the web or in social media also results in a huge explosion in demand for supporting keyword queries.