The advantage of configuring via ``HikariConfig`` over ``HikariDataSource`` is that when using the ``HikariConfig`` we know at ``DataSource`` construction-time what the configuration is, so the pool can be initialized at that point. However, when using ``HikariDataSource`` alone, we don't know that you are *done* configuring the DataSource until ``getConnection()`` is called. In that case, ``getConnection()`` must perform an additional check to see if the pool has been initialized yet or not. The cost (albeit small) of this check is incurred on every invocation of ``getConnection()`` in that case. In summary, intialization by ``HikariConfig`` is ever so slightly more performant than initialization directly on the ``HikariDataSource`` -- not just at construction time but also at runtime.
### Popular DataSource Class Names
We recommended using ``dataSourceClassName`` instead of ``driverClassName``/``jdbcUrl``, as using the driver class requires HikariCP to wrap the driver with an internal *DataSource* class. Here is a list of JDBC *DataSource* classes for popular databases:
Brett Wooldridge
11 years ago