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

On 10/28/2014 03:24 PM, Andres Freund wrote:
> On 2014-10-28 11:05:11 -0200, Arthur Silva wrote:
>> On Sat, Oct 25, 2014 at 12:38 PM, Andreas Karlsson <andreas@proxel.se>
>> As far as I'm aware int128 types are supported on every major compiler when
>> compiling for 64bit platforms. Right?
>
> Depends on what you call major. IIRC some not that old msvc versions
> don't for example. Also, there's a couple 32 platforms with int128 bit
> support. So I think we should just add a configure test defining the
> type + a feature macro.

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.

- Heikki