The built-in Hibernate connection pool

Hibernate will be connecting to the database on behalf of your application, so it needs to know how to obtain connections. For this tutorial we will be using a standalone connection pool (as opposed to a javax.sql.DataSource ). Hibernate comes with support for two third-party open source JDBC connection pools: c3p0 and proxool    .

<!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>