Sales of database software continue to rise at impressive rates. According to IT advisory group Gartner, the worldwide market for relational database management systems (RDBMS) software grew by 8.3% from 2004 to 2005, to $13.8 billion.

The top five vendors still account for over 91% of the total market. Microsoft showed the fastest growth, with sales were up 16.6% year on year. Much of that growth was driven by pent-up demand for its long-awaited SQL Server 2005, while Oracle saw sales rise, up 7.8% on 2004.

However, the most impressive growth – albeit from a much smaller base – was in open source database sales. Vendors such as MySQL and Ingres both outgrew their commercial rivals. Coleen Graham, a principal analyst at Gartner says: “These open source DBMS products continue to improve in terms of functionality and scalability, and DBMS tool vendors are beginning to provide support for these offerings.”

Indeed, the growth of open source software has promoted Gartner to revise its methodology for calculating market share. In the past, Gartner measured new license revenue; now new licenses and updates, as well as subscriptions to hosted models, technical support and maintenance, are included.

Of the platforms for RDBMS, open source Linux grew the fastest at 84% from 2004 to 2005. Gartner analysts predict that spending will continue to rise at least until 2010, as data management becomes evermore strategically important to companies.