The ZF1 Zend_Db reference manual has an entire section on performing transactions.
The ZF2 Zend\Db reference manual lacks any documentation on transactions.
How do I perform transactions in ZF2? Example code would be helpful.
The missing documentation is curious.
To find out what happened, I had to dive into the API docs for Zend\Db\Adapter.
It looks like beginTransaction, rollback and commit are defined in Zend\Db\Adapter\Driver\ConnectionInterface. This means that they are methods callable on every single adapter connection. Unfortunately the connection itself is rather buried.
What I'm not clear on -- and can't provide an example for at this time -- is figuring out which object you actually call these methods on. In the worst case, it looks like you might want to call $adapter->getDriver()->getConnection()->beginTransaction().
Eww.
I'm hoping someone else with more knowledge, and a copy of ZF2 handy, will see this and provide a better option.
Don't forget that you can just issue BEGIN TRANSACTION/ROLLBACK/COMMIT/SET autocommit=... SQL statements yourself. This is probably OK, as it doesn't look like Zend\Db keeps track of the transaction state.