TABLESAMPLE?

[Gerard Lemson]

Hi
> On Thu, Jul 18, 2019 at 11:34:15AM +0000, Gerard Lemson wrote:
> > > Question - what does the user want, a random percentage (P) of rows,
> > > or a random sample of (N) rows from the table ?
> > >
> > I would generally want a number of rows.
> 
> It is probably not surprising that I prefer a percentage -- I find it much more
> natural to say "Try on 1% of the data" than "Try on 10000 items".
> 
I think both for statistical and display purposes one may really *want* a number of rows.
And Dave's argument is that unless you know the total number you would not know what percentage to choose.
But the argument against also supporting ROWS is that, at least for MS SQL, it is not exact anyway.
So PERCENT only is ok with me.

> ...
> Note also that, as VODataService 1.2 comes in, users will have a reasonable
> way of estimating the number of rows they can expect when using
> percentages, as tables there can (and hopefully will) have an @nrows
> attribute.
> 
Good, that was going to be my suggestion.

Cheers,
Gerard

>         -- Markus