SIGMOD Record

note: With the exception of the last pages –which would be the back cover of the printed issue– that are not included in this file, it has the same contents as the printed edition. All the articles are also available individually online and have been put together here for convenience only.] SIGMOD Record SIGMOD Record is a quarterly publication of the Special Interest Group on Management of Data (SIGMOD) of the Association for Computing Machinery (ACM). SIGMOD is dedicated to the study, development, and application of database and information technology. SIGMOD Record Web Edition is also freely available online at SIGMOD Record solicits contributions of articles, technical notes, reports, and proposals for special sections. Conference announcements and calls for papers are published if relevant to the interests of the group and, in most cases, are limited to one page. All contributions should be sent to the editor for consideration. Submitted technical papers are reviewed for importance and correctness. Priority is given to papers that deal with current issues of interest to a broad audience. Papers should be submitted electronically in PDF format to [email protected], and they should follow a format similar to that of the SIGMOD conference proceedings (but with a larger font): 10 point font, single-space, 2-column, 8.5'' by 11'' page size with 1'' margins all around and no page numbers. They should also be formatted for letter size pages and must contain all fonts embedded. Submitted articles are limited to 6 pages unless prior agreement of the editor is obtained. By submitting your article for distribution in this Special Interest Group publication, you hereby grant to ACM the following non-exclusive, perpetual, worldwide rights: 1) to publish in print on condition of acceptance by the editor; 2) to digitize and post your article in the electronic version of this publication; 3) to include the article in the ACM Digital Library; and 4) to allow users to copy and distribute the article for noncommercial, educational or research purposes. However, as a contributing author, you retain copyright to your article and ACM will make every effort to refer requests for commercial use directly to you. Therefore, ACM is asking all newsletter authors to include their contact information in their submissions. Opinions expressed in articles and letters are those of the author(s) and do not necessarily express the opinions of the ACM or SIGMOD. Author(s) should be contacted for reprint authorization. As …