Re: extend pgbench expressions with functions

Hello, sorry for the silence.

At Fri, 18 Sep 2015 20:35:48 +0200 (CEST), Fabien COELHO <coelho@cri.ensmp.fr> wrote in
<alpine.DEB.2.10.1509182019100.27223@sto>
> > -1.  double is an inexact type, whereas integer is an exact type.
> 
> Sure. I already argue on that very line.

Agreed.

> > The typical way to handle this sort of thing is to define a struct
> > whose first member is a type field and whose second field is a union
> > of all the types you need to care about.
> 
> Yep.
> 
> > Then that gets passed around everywhere.  This patch should be
> > designed in such a way that if we eventually end up with functions
> > that have 10 different return types instead of 2 different return
> > types, we don't need to add 8 more parameters to any functions.
> > Instead, those still return PgBench_Value (or whatever we call it)
> > which is the aforementioned struct, but there are more options for
> > what that can contain.
> 
> I just put the double type as a proof of concept, but for pgbench only
> integers really matters.
> 
> What you suggest would work, but it would also result in ugly and
> lengthy code, as I argued in another mail, because you have to decide
> for overloaded operators and functions which actual typed operator
> must be called, and then perform the necessary type conversions
> depending on the actual type of the operands. The implicit descendent
> typing used in the patch hides this, and is more than enough for
> pgbench, IMO.

I also agree this.

> If this is a blocker, I would rather remove the support for doubles
> than write verbose and inelegant code.

I understood the situation and agreed for current shape of the
code. I no longer object the calling-alternatively code. But I'd
like see the abbreviated discussion in the comment on the
function.

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center