On Mon, 27 Feb 2006, Nikolay Samokhvalov wrote:
> On 2/27/06, Bruno Wolff III <bruno(at)wolff(dot)to> wrote:
> The alternatives to distinct on are painful. They are generally both harder
> to read and run slower.
>
>'DISTINCT ON' is evil constuction, because (w/o any 'ORDER BY') it
>produses unpredictable result, as 'ORDER BY random()' does.
And so does UNION in the standard under some circumstances (look at
anywhere in the spec that a query expression is possibly
non-deterministic), so I think that's a weak argument.