Re: Improving and extending int128.h to more of numeric.c

On Tue, Jul 15, 2025 at 4:07 AM Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>
> I have reduced the number of iterations and changed it to use the
> current time for the PRNG seed. I don't see much value in logging the
> seed though, since we already log the inputs that cause any failure.

Ah, right.

On Mon, Jun 23, 2025 at 3:01 PM Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
> 0005 is the main patch. It adds a few more functions to int128.h and
> uses them in numeric.c to allow various functions (mainly aggregate
> functions) to use 128-bit integers unconditionally on all platforms.
> This applies to the following aggregates:
>
> - sum(int8)
> - avg(int8)
> - stddev_pop(int4)
> - stddev_samp(int4)
> - var_pop(int4)
> - var_samp(int4)

> Testing on a 32-bit system without native int128 support, I see
> something like a 1.3-1.5x speedup in a couple of simple queries using
> those aggregates.

With v5, I don't see any difference from master when building on x86
with -m32 for these queries:

select sum(i) from generate_series(1e10, 1e10+1e6, 1) i;
select var_pop(i) from generate_series(1e9, 1e9+1e6, 1) i;

Which queries were you testing?

(Also, unrelated to the patch set, but I was surprised to find
replacing the numeric expressions above with bigint ones
(10_000_000_000 etc) makes the queries at least 5 times slower, and
that's true with a normal 64-bit build as well.)

--
John Naylor
Amazon Web Services