Efficient Rewriting Algorithms for Preference Queries

Preference queries are crucial for various applications (e.g. digital libraries) as they allow users to discover and order data of interest in a personalized way. In this paper, we define preferences as preorders over relational attributes and their respective domains. Then, we rely on appropriate linearizations to provide a natural semantics for the block sequence answering a preference query. Moreover, we introduce two novel rewriting algorithms (called LBA and TBA) which exploit the semantics of preference expressions for constructing progressively each block of the answer. We demonstrate experimentally the scalability and performance gains of our algorithms (up to 3 orders of magnitude) for variable database and result sizes, as well as for preference expressions of variable size and structure. To the best of our knowledge, LBA and TBA are the first algorithms for evaluating efficiently arbitrary preference queries over voluminous databases.

[1]  Ralf Rantzau,et al.  Context-sensitive ranking , 2006, SIGMOD Conference.

[2]  Kenneth A. Ross,et al.  Practical Preference Relations for Large Data Sets , 2007, 2007 IEEE 23rd International Conference on Data Engineering Workshop.

[3]  Jan Chomicki,et al.  Preference formulas in relational queries , 2003, TODS.

[4]  Kenneth A. Ross.  On the Adequacy of Partial Orders for Preference Composition , .

[5]  Bernhard Seeger,et al.  An optimal and progressive algorithm for skyline queries , 2003, SIGMOD '03.

[6]  Georgia Koutrika,et al.  Personalized queries under a generalized preference model , 2005, 21st International Conference on Data Engineering (ICDE'05).

[7]  Ronen I. Brafman,et al.  Reasoning With Conditional Ceteris Paribus Preference Statements , 1999, UAI.

[8]  Jan Chomicki.  Iterative Modification and Incremental Evaluation of Preference Queries , 2006, FoIKS.

[9]  Werner Kießling,et al.  Optimization of Relational Preference Queries , 2005, ADC.

[10]  Pierre-Yves Schobbens,et al.  Operators and Laws for Combining Preference Relations , 2002, J. Log. Comput..

[11]  Ronen I. Brafman,et al.  CP-nets: Reasoning and Consistency Testing , 2002, KR.

[12]  Nicolas Spyratos,et al.  Querying with Preferences in a Digital Library , 2005, Federation over the Web.

[13]  Werner Kießling,et al.  Preference Queries with SV-Semantics , 2005, COMAD.

[14]  Wolf-Tilo Balke,et al.  Multi-objective Query Processing for Database Systems , 2004, VLDB.

[15]  Denis Bouyssou,et al.  Introduction to topics on preference modelling , 1998, Ann. Oper. Res..

[16]  Ronald Fagin,et al.  Comparing and aggregating rankings with ties , 2004, PODS '04.

[17]  Peter Buneman,et al.  Using Powerdomains to Generalize Relational Databases , 1991, Theor. Comput. Sci..

[18]  Georgia Koutrika,et al.  Personalization of queries in database systems , 2004, Proceedings. 20th International Conference on Data Engineering.

[19]  Georgia Koutrika,et al.  Personalized Systems: Models and Methods from an IR and DB Perspective , 2005, VLDB.

[20]  Qing Liu,et al.  Efficient Computation of the Skyline Cube , 2005, VLDB.

[21]  Werner Kießling,et al.  Foundations of Preferences in Database Systems , 2002, VLDB.

[22]  Moni Naor,et al.  Optimal aggregation algorithms for middleware , 2001, PODS '01.

[23]  Werner Kießling,et al.  The BNL + + Algorithm for Evaluating Pareto Preference Queries , 2006 .

[24]  Donald Kossmann,et al.  The Skyline operator , 2001, Proceedings 17th International Conference on Data Engineering.

[25]  Jignesh M. Patel,et al.  Efficient Skyline Computation over Low-Cardinality Domains , 2007, VLDB.

[26]  Luca Cardelli,et al.  On understanding types, data abstraction, and polymorphism , 1985, CSUR.

[27]  Kian-Lee Tan,et al.  Stratified computation of skylines with partially-ordered domains , 2005, SIGMOD '05.

[28]  Jan Chomicki,et al.  Semantic Optimization of Preference Queries , 2004, CDB.

[29]  Riccardo Torlone,et al.  Which are my preferred items , 2002 .

[30]  Elhadji Mamadou Nguer.  Semantics and Pragmatics of Preference Queries in Digital Libraries , 2007, ECDL.

[31]  Donald Kossmann,et al.  Shooting Stars in the Sky: An Online Algorithm for Skyline Queries , 2002, VLDB.