The worldwide relational database management systems market saw a 12.6 percent growth spike in 2007 to US$18.8 billion compared to $16.7 billion in 2006, according to IDC.

While new features and innovations helped drive up revenue, some of the market's overall growth is also attributable to fluctuations in currency exchange rates, noted the report's author, analyst Carl Olofson. The weak US dollar has help drive up software vendors' reported revenues outside the country.

Oracle once again took the top spot, capturing 44.3 percent of the market with revenue growth of 13.3 percent. IBM came in second with a 21 percent share, also logging a 13.3 percent revenue growth rate. It was followed by Microsoft, with 18.5 percent of the market and a 14 percent jump in revenue.

Sybase and Teradata rounded out the top five, garnering market shares of 3.5 percent and 3.3 percent, respectively.

Oracle's continued strength came from sales of database options, such as its Real Application Clusters offering, Olofson said. "Oracle Database 11g has experienced unusually high early adoption rates for a major release," he added.

The top five vendors take up more than 90 percent of the market, but "there is plenty of dynamism and growth potential" in the other 10 percent, Olofson wrote.

For example, the open-source database maker Ingres took just .1 percent of the market in 2007, but that represented a 206.6 percent growth rate, according to the report.