Cupertino, Calif.-based Solid will make a prototype of its online transaction processing storage engine, solidDB, available for download next Monday. The release coincides with the start of MySQL's annual user conference in Santa Clara, Calif.

So far, solidDB has been deployed 3 million times, according to Paola Lubet, vice president for marketing and business development. It has mostly been embedded in telecom and networking hardware from companies such as Siemens AG, Nortel Networks Corp. and Cisco Systems Inc., as well as in the OpenView monitoring software from Hewlett-Packard Co. But Lubet said the software is being used by 120 enterprise customers, including, among others, financial firms that use solidDB for handling live trading data.

The popular open-source MySQL database allows users to choose different methods for storing data. MyISAM is the default storage engine, but many users choose to use another bundled engine, InnoDB, which is seen as more reliable and faster for many scenarios.

InnoDB's parent company, Innobase OY Inc., was bought by Oracle last October. That sparked fears that Oracle might use its ownership of InnoDB technology to hurt MySQL. That hasn't happened, although Oracle tried unsuccessfully to buy MySQL.

MySQL renewed its contract for Oracle to continue supporting Innobase in early April, though it is developing its own storage engine.