Andrey Balmin  IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (abalminus.ibm.com). Dr. Balmin is a research staff member in the Exploratory Database department at IBM's Almaden Research Center. He is a member of the cross-divisional team that extended DB2 Universal Database for Linux, UNIX, and Windows to provide native XML and XQuery support. Within this project, he is responsible for XML index eligibility and XML cardinality and cost estimation modules. His research interests include querying and management of semistructured data, as well as integration of structured and unstructured search technologies. He received a Ph.D. degree from the University of California at San Diego.

Tom Eliaz  IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (teliazus.ibm.com). Mr. Eliaz is a software engineer in IBM's Silicon Valley Lab. He is a member of the DB2 Universal Database for Linux, UNIX, and Windows query compiler team and is focused on extending the DB2 optimizer with native XML and XQuery support. He graduated from the University of Pennsylvania with a B.S. degree in computer science and has worked for IBM on the query optimizer since 2002.

John Hornibrook  IBM Software Group, 8200 Warden Ave., Markham Ontario L6G 1C7, Canada (jhornibrca.ibm.com). Mr. Hornibrook is the development manager for the optimizer, runstats, and explain components of DB2 Universal Database for Linux, UNIX, and Windows. He has been a DB2 developer for 14 years, working on various DB2 engine components, including Relational Data Services and the SQL Compiler.

Lipyeow Lim  IBM Thomas J. Watson Research Center, 19 Skyline Drive, Hawthorne, New York 10532 (liplimus.ibm.com). Dr. Lim is a research staff member at the Watson Research Center. He is part of the team that prototyped and developed the XML runstats component in DB2. His research interests lie in the field of data management, in particular, statistics collection and storage for database query optimization.

Guy M. Lohman  IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (lohmanalmaden.ibm.com). Dr. Lohman is the manager of Advanced Optimization in the Advanced Database Solutions department at IBM's Almaden Research Center. He has over 23 years of experience in relational query optimization. He is the architect of the optimizer of the DB2 Universal Data Base (UDB) for Linux, UNIX, and Windows, and was responsible for its development in Versions 2 and 5, as well as the invention and prototyping of Visual Explain. During that period, Dr. Lohman also managed the overall effort to incorporate into the DB2 UDB product the Starburst compiler technology that was prototyped at the Almaden Research Center. More recently, he was a co-inventor and designer of the DB2 Index Advisor (now part of the Design Advisor) and co-founder of the DB2 Autonomic Computing project. In 2002, Dr. Lohman was elected to the IBM Academy of Technology. His current research interests involve query optimization, self-managing database systems, and problem determination.

David Simmen  IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (simmenus.ibm.com). Mr. Simmen is a Senior Technical Staff Member in the Exploratory Database department at IBM's Almaden Research Center. He was formerly the technical lead of the DB2 Universal Database for Linux, UNIX, and Windows query optimization team and managed the Silicon Valley Laboratory branch of the team. He was a member of the cross-divisional team that developed the DB2 optimizer from a research prototype and spent a large portion of his IBM career leading efforts to extend that technology. His research interests include query processing and the integration of content, database, and text-processing systems. He joined IBM after receiving a B.S. degree in applied mathematics from Carnegie Mellon University in 1989.

Min Wang  IBM Thomas J. Watson Research Center, 19 Skyline Drive, Hawthorne, New York 10532 (minus.ibm.com). Dr. Wang received a Ph.D. degree in computer science from Duke University in 1999. She is currently a research staff member at the Watson Research Center in Hawthorne, New York. Her research interests include query optimization, approximate query processing, data mining, electronic commerce, and database security.

Chun Zhang  Cosmix Corporation, 444 Castro Street, Suite 700, Mountain View, California 94041 (yazhangchunyahoo.com). Dr. Zhang is currently a member of the technical staff at Cosmix Corporation in Mountain View, California. The work described in this paper was done while she was a research staff member at IBM's Almaden Research Center and part of the DB2 XML optimizer team focusing on the design and development of the query optimizer. She has extensive experience in structured, semistructured, and unstructured data management. Her current work involves text-mining and search-engine technologies. She is also interested in storage, query processing, and optimization. Dr. Zhang received a Ph.D. degree from the University of Wisconsin at Madison.