--- In firebird-support@yahoogroups.com, Richard Wesley <hawkfish@...>
wrote:

>
> It computes the rand() value independently for every row and then
> returns only those rows where this value is less than .01 (i.e. about
> 1% of the table).
>

Very clever. I didn't know that could be done.

>
> The idea is that if FB makes a copy of the table before
> applying the where, then this is a very inefficient query.
>

Agreed. But I see nothing that indicates that FB is doing that.

Thanks for your comments.