Several strong databases are available for Linux.
MySQL
MySQL has been known for being a lightning fast, free database. In exchange for its speed, however, it lacks certain essential features. MySQL's wide acceptance means that it has received extensive testing from a wide variety of users, whose requirements range from small data sets to very large data sets. Many applications do not require features such as embedded SQL, full ACID compliance, triggers, foreign keys, etc., but as they grow into enterprise applications that do require such features, one of the easiest upgrade paths is to purchase commercial, feature-packed versions of MySQL.
PostGreSQL
Known for containing the essential features that are lacking in MySQL, optimized versions of PostGreSQL now compete on speed as well.
Oracle
A strong option for enterprise customers, Oracle offers its database products on Linux because Linux offers more ways to optimize stability and speed, both of which are essential to Oracle's clients.
TCEG Support for Linux Databases
TCEG provides support for applications utilizing any of the above databases and can provide assistance with installation, administration, and crash recovery.