See ma.gnol.ia for an example of what can happen with a DBMS that doesn't provide this. That's a big reason why I use Postgres instead of MySQL. With Postgres, the database won't get corrupted by a partially complete operation.
On the other hand, MySQL gets better performance by skipping the whole ACID part... so if you are willing to work with this (i.e. you have a good disaster recovery strategy) then you can theoretically handle a higher load by using MySQL.
Good point, and I didn't mean to suggest that the one precludes the other. However, the ma.gnol.ia story is a tale of redundancy - they were backing up corrupted data for weeks, and once they realized this, it was too late. The database took weeks to fail, and their backups were worthless.
See ma.gnol.ia for an example of what can happen with a DBMS that doesn't provide this. That's a big reason why I use Postgres instead of MySQL. With Postgres, the database won't get corrupted by a partially complete operation.
On the other hand, MySQL gets better performance by skipping the whole ACID part... so if you are willing to work with this (i.e. you have a good disaster recovery strategy) then you can theoretically handle a higher load by using MySQL.