Re: [WIP Patch] Using 128-bit integers for sum, avg and statistics aggregates

Heikki Linnakangas <hlinnakangas@vmware.com> writes:
> It wouldn't be too hard to just do:

> struct {
>      int64 high_bits;
>      uint64 low_bits;
> } pg_int128;

> and some macros for the + - etc. operators. It might be less work than 
> trying to deal with the portability issues of a native C datatype for this.

-1.  That's not that easy, especially for division, or if you want to
worry about overflow.  The point of this patch IMO is to get some low
hanging fruit; coding our own int128 arithmetic doesn't sound like
"low hanging" to me.

Also, we've already got the configure infrastructure for detecting
whether a platform has working int64.  It really shouldn't be much
work to transpose that to int128 (especially if we don't care about
printf support, which I think we don't).
        regards, tom lane