The DatabaseAdaptor class is an abstract class that all SQL adaptors should extend. It implements the Sql interface found at phork/php/database/interfaces/Sql.interface.php.
In addition to being a straight forward adaptor, each adaptor class has the ability to read from and write to different databases, allowing for master-slave replication. It's also possible to add other database connections in addition to the standard read and write. All database connections are defined in the database configuration.