> For example, if we had reason to be concerned about *adversarial*
> inputs, I think that there is a good chance that our qsort() actually
> would be problematic to the point of driving us to prefer some generally
> slower alternative.
That is an interesting point.
Indeed, a database in general often stores user-supplied data, which may
happen to be sorted for presentation purpose in an interface. Same thing
occured with hashtable algorithms and was/is a way to do DOS attacks on
web applications. I'm not sure whether the qsort version discussed here
would apply on user-supplied data, though. If so, adding some randomness
in the decision process would suffice to counter the adversarial input
argument you raised.
--
Fabien.
