> Oracle does, but you pay in other ways. Instead of keeping dead tuples
> in the main heap, they shuffle them off to an 'undo log'. This has some
> downsides:
>
> Rollbacks take *forever*, though this usually isn't much of an issue
> unless you need to abort a really big transaction.
It's a good point though. Surely a database should be optimised for the
most common operation - commits, rather than rollbacks?
Chris