[[_database]]

== Relational Database Setup
{{book.project.name}} comes with its own embedded Java-based relational database called H2.
This is the default database that {{book.project.name}} will use to persist data and really only exists so that you can run the authentication
server out of the box.  We highly recommend that you replace it with a more production ready external database.  The H2 database
is not very viable in high concurrency situations and should not be used in a cluster either.  The purpose of this chapter is to
show you how to connect {{book.project.name}} to a more mature database.

{{book.project.name}} uses two layered technologies to persist its relational data.  The bottom layered technology is JDBC.  JDBC
is a Java API that is used to connect to a RDBMS.  There are different JDBC drivers per database type that are provided
by your database vendor.  This chapter discusses how to configure {{book.project.name}} to use one of these vendor-specific drivers.

The top layered technology for persistence is Hibernate JPA.  This is a object to relational mapping API that maps Java
Objects to relational data.  Most deployments of {{book.project.name}} will never have to touch the configuration aspects
of Hibernate, but we will discuss how that is done if you run into that rare circumstance.

NOTE:  Datasource configuration is covered much more thoroughly in link:{{book.appserver.doc_base_url}}{{book.appserver.version}}{{book.appserver.datasource_ref.link}}[{{book.appserver.datasource_ref.name}}]
       in the _{{book.appserver.admindoc.name}}_.