Databases to Evaluate.

Our current list, with brief reasons is:

MySQL - public domain DBMS, used by many astronomical sites, reputed to be very fast (especially the back-ends which do not support transactions).

PostgreSQL - public domain DBMS, used by several astro sites, supports data structures so object-relational, has R-tree indexing built-in, which may assist in indexing on spherical-polar coordinates.

Sybase - perhaps ethe most widely used commercial DBMS in astronomy, because it seems to have a number of functions useful in handling scientific data.

DB2 - large package, also said to be object-relational, supported by IBM, many language interfaces, cheap/free licences available on Linux. The optional Spatial extender is Open GIS compliant.

Oracle - the most successful DBMS in the world for commercial purposes. The lack of support (until very recently) for IEEE-754 format floating-point numbers indicates that scientific users have been low on Oracle's priority list. Licence costs tend to be high, and while several astronomical sites use it, this is often because they already have a site licence. Oracle 8i has a spatial data handling option, based on Helical Hyperspatial code (HHCODE) similar to a z-ordering mapping function.

SQL Server - only available on one platform (Windows) and unlikely ever to be available on Linux; no 64-bit version yet. But now in use by Sloan Digital Sky Survey for their SkyServer .

Others that we considered but are not on the priority list:

Informix - some interesting features, e.g. R-trees and datablades for multi-dimensional indexing. Two papers on it by A.Baruffolo in ADASS-VIII conference proceedings. But now Informix has been taken over by IBM its future seems uncertain.

Interbase - owned by Borland, but free version available. Standard RDBMS, but no known users in astronomy.

Objectivity/DB - OODBMS used by Sloan digital sky survey, and by the Babar database at Stanford where it stores 496 TB of data. But problems and doubts over its future have led to Sloan porting their SX system to Microsoft SQL-server.

O2 - another OODBMS with good interfaces to C as well as C++, and ability to suffer schema changes gracefully. Unfortunately a series of take-overs have left it as a mature product (a euphemism for defunct). We use it at Leicester, but support is now expensive, and I think it is no longer on sale to new users.

-- ClivePage - 19 April 2002

-- TonyLinde - 15 Mar 2002