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Advances in Astronomy
Volume 2010 (2010), Article ID 524534, 11 pages
Research Article

Multiple Depth DB Tables Indexing on the Sphere

1Istituto Nazionale di Astrofisica, IASF Bologna, Via P. Gobetti 101, 40129 Bologna, Italy
2Istituto Nazionale di Astrofisica, IASF Palermo, Via U. La Malfa 153, 90146 Palermo, Italy

Received 30 June 2009; Revised 13 October 2009; Accepted 12 January 2010

Academic Editor: Joshua S. Bloom

Copyright © 2010 Luciano Nicastro and Giorgio Calderone. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Any project dealing with large astronomical datasets should consider the use of a relational database server (RDBS). Queries requiring quick selections on sky regions, objects cross-matching and other high-level data investigations involving sky coordinates could be unfeasible if tables are missing an effective indexing scheme. In this paper we present the Dynamic Index Facility (DIF) software package. By using the HTM and HEALPix sky pixelization schema, it allows a very efficient indexing and management of spherical data stored into MySQL tables. Any table hosting spherical coordinates can be automatically managed by DIF using any number of sky resolutions at the same time. DIF comprises a set of facilities among which SQL callable functions to perform queries on circular and rectangular regions. Moreover, by removing the limitations and difficulties of 2-d data indexing, DIF allows the full exploitation of the RDBS capabilities. Performance tests on Giga-entries tables are reported together with some practical usage of the package.