Re: pow support for pgbench

Hi Fabien,

Thanks for the review.
I've fixed the documentation and added an ipow function that handles both
positive and negative ints, having 0^0 == 1 and 0^(negative) == PG_INT64_MAX
since that's what my glibc math.h pow() is returning.

On Sat, Nov 4, 2017 at 12:34 PM, Fabien COELHO <coelho@cri.ensmp.fr> wrote:

>
> Hello Raúl,
>
> Sorry about the patch. Attaching it now so it can be considered as
>> submitted.
>>
>
> There is a typo in the XML doc:
>
>         <literal>1024.0/<literal>
>
> Please check that the documentation compiles.
>
> I'm at odds with having the integer version rely on a double pow(), even
> if it works. I think that there should be a specific integer version which
> does use integer operations. From stack overflow, the following is
> suggested:
>
>  int ipow(int base, int exp)
>  {
>     int result = 1;
>     while (exp)
>     {
>         if (exp & 1)
>             result *= base;
>         exp >>= 1;
>         base *= base;
>     }
>
>     return result;
>  }
>
> The integer version should be when x & y are integers *AND* y >= 0.
>
> if y is a negative integer, the double version should be used.
>
> --
> Fabien.




-- 

*Raúl Marín Rodríguez*carto.com