Both Memcached, which accelerates existing relational databases like MySQL, and Redis, which is a complete, stand-alone database and acceleration solution, are open source technologies.

FORBES: Big Data and NoSQL: Five Key Insights

For one thing, it says, MySQL and Oracle's databases do not compete: the former is a relatively simple program used by many websites, while the latter is complex software that underpins corporate applications.

ECONOMIST: Oracle and Sun Microsystems

Last December ten times as many came and on the stage were plenty of Europeans, including Marten Mickos of MySQL, a maker of databases now owned by Oracle, a software giant, Marc Simoncini, founder of meetic.com, Europe's largest dating site, and Niklas Zennstrom, who started Skype.

ECONOMIST: Europe's tech entrepreneurs

If Oracle's acquisition of Sun Microsystems goes through, it will have an even bigger open-source portfolio including MySQL, a popular program for databases.

ECONOMIST: Open-source software in the recession: Born free | The

At the low-price end, open-source upstarts MySQL and Enterprisedb have hawked cheaper, nimbler databases for a few years, possibly squeezing Ingres out.

FORBES: Terry Versus Larry

"All other databases on the market today were designed for an offline, back-office use, " says MySQL Chief Executive Marten Mickos.

FORBES: Magazine Article