TAILIEUCHUNG - Keyword Search in Databases- P3

Keyword Search in Databases- P3:Conceptually, a database can be viewed as a data graph GD(V ,E), where V represents a set of objects, and E represents a set of connections between objects. In this book, we concentrate on two kinds of databases, a relational database (RDB) and an XML database. In an RDB, an object is a tuple that consists of many attribute values where some attribute values are strings or full-text; there is a connection between two objects if there exists at least one reference from one to the other | I Preface It has become highly desirable to provide flexible ways for users to query search information by integrating database DB and information retrieval IR techniques in the same platform. On one hand the sophisticated DB facilities provided by a database management system assist users to query well-structured information using a query language based on database schemas. Such systems include conventional rdbmss such as DB2 ORACLE SQL-Server which use SQL to query relational databases RDBs and XML data management systems which use XQuery to query XML databases. On the other hand IR techniques allow users to search unstructured information using keywords based on scoring and ranking and they do not need users to understand any database schemas. The main research issues on DB IR integration are discussed by Chaudhuri et al. 2005 and debated in a SIGMOD panel discussion Amer-Yahia et al. 2005 . Several tutorials are also given on keyword search over RDBs and XML databases including those by Amer-Yahia and Shanmugasundaram 2005 Chaudhuri and Das 2009 Chen et al. 2009 . The main purpose of this book is to survey the recent developments on keyword search over databases that focuses on finding structural information among objects in a database using a keyword query that is a set of keywords. Such structural information to be returned can be either trees or subgraphs representing how the objects which contain the required keywords are interconnected in an RDB or in an XML database. In this book we call this structural keyword search or simply keyword search. The structural keyword search is completely different from finding documents that contain all the user-given keywords. The former focuses on the interconnected object structures whereas the latter focuses on the object content. In a DB IR context for this book we use keyword search and keyword query interchangeably. We introduce forms of answers scoring ranking functions and approaches to process keyword queries. .

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