The eZ Publish Extension for Oracle® Database (also known as the "ezoracle" extension or "database extension") makes it possible to use Oracle as a database server for eZ Publish.

The communication/interaction between eZ Publish and the database is done via the "ezdb" library, which provides a database abstraction layer. This allows developers to access the database using a generic/unified API that is independent when it comes to different databases and their specific ways of doing things. The "ezdb" library supports MySQL and PostgreSQL databases by default. The database extension contains a database driver implementation (also called the "ezoracle" database handler) that makes it possible for the "ezdb" library to connect to an Oracle database. The extension itself makes use of the PHP Oracle functions. This means that you have to make sure that your PHP installation supports Oracle. Refer to the documentation of PHP for more information.

You need to use the database extension if you wish to do one of the following:

• Create a new eZ Publish site that uses an Oracle database from the beginning.
• Migrate an existing site that uses a MySQL database to Oracle.
• Access an external Oracle database from an eZ Publish site using the ezdb abstraction layer

Note that migration from PostgreSQL is not supported. In addition, once you have migrated from MySQL to Oracle, migrating back to either MySQL or PostgreSQL is not a trivial task, and the database extension does not provide scripts for that.

If your site is running on MySQL/PostgreSQL and you do not plan on migrating to Oracle but only need to execute a few Oracle queries (e.g., you need to fetch some data from the Oracle database for one of your pages), you can choose between the following alternatives:

• Install the database extension and interact with the Oracle database using the wrapper functions provided by the "ezdb" library.
• Do not install the extension and interact with the Oracle database directly using the PHP Oracle functions. Be aware that if the external Oracle database is later replaced by another database solution (MySQL, PostgreSQL, MSSQL, etc.), you will have to rewrite parts of the code that make direct use of the Oracle database functions.