SIGMOD/PODS 2011 June 12 th -16 th , 2011 Athens, Greece Conference Program ACM SIGMOD International Conference on Management of Data & ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems SIGMOD/PODS 2011 June 12 th – June 16 th , 2011 Athens, Greece http://www.sigmod2011.org Conference Program 1 Copyright © 2011 Editors: Tasos Kementsietsidis (IBM T.J. Watson), Yannis Velegrakis (University of Trento) Conference Proceedings Chairs Template: Yannis Velegrakis, Toronto 2004, Available for download at: http://db.disi.unitn.eu/pages/programBooklet Permission to use the template is granted, with the kind request to include the current notice in the booklet. 2 TABLE OF CONTENTS Table of Contents .................................................................................................................. 3 Welcome Messages .............................................................................................................. 5 Conference Organization .................................................................................................. 11 Conference Venue ............................................................................................................. 17 Program at a Glance ........................................................................................................... 23 Session Contents ................................................................................................................. 27 Social Events ........................................................................................................................ 47 Awards .................................................................................................................................. 51 Keynotes ............................................................................................................................... 57 Tutorials ................................................................................................................................ 61 Panels ..................................................................................................................................... 67 SIGMOD Research Paper Abstracts .............................................................................. 69 PODS Paper Abstracts ....................................................................................................... 93 SIGMOD Industrial Paper Abstracts .......................................................................... 101 SIGMOD Demonstration Abstracts ............................................................................ 107 Undergraduate Poster Competition ............................................................................. 115 Graduate Poster Abstracts .............................................................................................. 117 Programming Contest Finalists .................................................................................... 119 Co-Located Workshops .................................................................................................. 121 Local Information ............................................................................................................ 123 Notes Space ....................................................................................................................... 129 3 4 Welcome to SIGMOD 2011 WELCOME MESSAGES Welcome message from the SIGMOD Chairs Welcome to an exciting week in the city of Athens for the 2011 ACM SIGMOD Conference. Athens is a metropolitan and cosmopolitan city, with so many things to do and to see. It is also known as the birth place of Democracy, the city with the world-renown "Acropolis and Parthenon", with the famous Theater of Herodes Atticus and the "marble stadium" where the first modern time Olympic Games took place in 1896, home of Socrates, Plato, Pericles (Golden Age), and home of the very successful 2004 Olympic Games. And now the home of the 2011 ACM SIGMOD Conference! Athens is both an "ancient" and a "modern" city, in which visitors can walk safely and enjoy the rich - almost 5,000 year old - history it has to offer. The city offers a lot of sightseeing, museums, shopping and nightlife. We have a program of several social events to complement an excellent technical program. The SIGMOD banquet is in the beautiful Island Restaurant by the sea, the SIGMOD reception on Monday at the Caravel Hotel (conference hotel) Roof Garden, and the PODS 30th Anniversary Colloquium and Reception on Sunday also at the hotel. Through the generous support from our sponsors (Platinum) EMC, Microsoft, and Oracle, (Gold) Google, IBM Research, SAP, Sybase, and Yahoo! Labs, (Silver) AsterData, HP, Intrasoft International, Kosmix, MarkLogic, Twitter, and VirtualTrip, and (Other Supporters) Greenplum and NEC, along with a contribution from ACM SIGMOD, we were able to keep the conference fees to a minimum with an extraordinarily low student registration that will allow many students to participate. The scientific program was designed by over 150 dedicated volunteers. We would like to thank our chairs for all the time, knowledge, and insight they put into creating a very exciting program. In particular, we would like to thank our tutorial co-chairs Susan Davidson (University of Pennsylvania) and Tova Milo (Tel Aviv University), the keynote and panel chair Pat Selinger (IBM Research - Almaden), the industrial program co-chairs Richard Hull (IBM Research - Thomas J. Watson Research Ctr.) and Raghu Ramakrishnan (Yahoo! Research), the demonstration chair Chris Jermaine (Rice University), the workshop chair Christian S. Jensen (Aarhus University), and the undergraduate research program chair Irini Fundulaki (Institute of Computer Science - FORTH), along with our very wise advisory committee Laura Hass (IBM Research - Almaden) and Donald Kossmann (ETH Zurich). We also thank the SIGMOD Executive Committee for their guidance with special thanks to Lisa Singh for providing tremendously valuable history and advice. We had 375 research papers submitted. A research program committee provided detailed reviews and extensive discussion following SIGMOD's double-blind reviewing policy. The program committee was led by nine group leaders: Sihem Amer-Yahia (Yahoo! Labs), Michael Böhlen (University of Zurich), Bettina Kemme (McGill University), Sam Madden (MIT), Jignesh Patel (University of Wisconsin), Dan Suciu (University of Washington), Wang-Chiew Tan (IBM Research - Almaden and UC Santa Cruz), Nesime Tatbul (ETH Zurich), and Min Wang (HP Labs China). The group leaders ensured that every paper had a champion and received thorough discussion. We accepted a record number of research papers. Nonetheless, it is clear there were still papers that were rejected that would have been valuable contributions to SIGMOD. The group leaders did a great job in keeping the discussions positive and reviewers focused on finding reasons to accept papers, rather than reasons to reject. We hope that SIGMOD continues the trend of accepting more papers to accommodate all the great ideas being produced by the community. All research papers have been invited to participate in SIGMOD’s Experimental Repeatability effort, the goal of which is to help to enable SIGMOD papers to stand as reliable, archival work for future research. A demonstration program committee of 35 people reviewed 81 proposals for system demonstrations and accepted 32. We will again be holding a Best Demonstration Award Competition to recognize the most innovative demonstrations. We encourage everyone to participate in the voting. An industrial program committee of 13 people reviewed 36 short presentation proposals, accepting 14. In addition, the industrial program will include two invited talks by Michael Abbott (Twitter) and Don Campbell (IBM). Rounding out the full program, we have a panel on data management issues in health and medical informatics, two invited talks by James Hamilton (Amazon) and Anastasia Ailamaki (EPFL), along with six tutorials on new applications of Datalog, flash memory, copy detection, data privacy, web data management, and statistical relational models. SIGMOD continues its commitment to undergraduate research awarding eight scholarships to undergraduate researchers who will participate in the Undergraduate Research Poster session that will be co-located with a 5 Welcome to SIGMOD 2011 Graduate Research Poster session. In addition, we will host the Third Annual SIGMOD Programming Contest. Student teams from degree granting institutions were invited to compete in this annual contest. This year, the task is to implement a high-throughput main-memory index that is made durable using a flash- based SSD. On behalf of the conference organization committee, we would like to thank you all for your submissions to SIGMOD 2011, your hard work serving on SIGMOD 2011 committees, and for participating in the conference. It is your ideas, interest and input that shaped the conference and that continue to make it such a valuable venue for our community. Timos Sellis Renée J. Miller Anastasios Kementsietsidis Yannis Velegrakis General Chair Program Chair Proceedings Co -Chair Proceedings Co -Chair 6 Welcome to SIGMOD 2011 Welcome Message from the PODS General Chair It is our great pleasure to welcome you to the 2011 ACM Symposium on Principles of Database Systems – PODS’11. This year’s symposium continues its tradition of being the premier international conference on the theoretical aspects of data