What databases does Plone integrate with?
Plone comes with a reliable, secure, easy-to-administer object database backend known as the ZODB (Zope Object Database). In addition, Plone can easily connect to data stored in Active Directory, LDAP, Salesforce.com, SQL databases, and more.
A free Plone add-on, RelStorage, also allows enterprises with investments in Oracle, MySQL and PostgreSQL to store the data driving their Plone site in their existing infrastructure to be able to make use of familiar tools, clustering and failover solutions.

