[idm]

ACID: Atomicity, Consistency, Isolation, Durability

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.

[teej]

ACID isn't an excuse to skip redunancy and backups.

[idm]

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.