Earlier quoted context omitted.
As others have said, this appears to be a total dump of the system and not just the database. It looks like the encryption keys were not kept with the database, but all of the SSL keys and everything are included inside the full dump. Seemingly it was another server with the keys that was dumped too. The only way to protect against this would be some type of hardware key store with limited access to all employees and…
If the keys are only ever held in memory then getting a dump of all the stored data from all the database and font-end servers would not reveal the keys. To achieve that you would need human interaction to bring up a new box (or after an existing box is restarted) in order to hand over the keys (if the server could request the key from somewhere on the local network, then perhaps so can an attacker if they get access…
In a big company though, having that one developer with full keys to the kingdom and is the only way to start up new servers is obviously out of the picture. Especially if the system works by having the keys on an easily stolen or damaged laptop...