Re: Speed up COPY FROM text/CSV parsing using SIMD

Hi,

On Fri, 13 Mar 2026 at 17:05, Nathan Bossart <nathandbossart(at)gmail(dot)com>
wrote:
>
> On Fri, Mar 13, 2026 at 04:34:49PM +0300, Nazir Bilal Yavuz wrote:
> > On Fri, 13 Mar 2026 at 14:57, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
wrote:
> >> Unfortunately, v15 causes a regression for a 'csv & wide & 1/3' case
> >> on my end. v14 was taking 8000ms but v15 took ~9100ms. If we add the
> >> tmp_hit_eof variable then the regression disappears. Also, if I use a
> >> struct like below, regression disappears again.
> >
> >> When I removed the tmp_hit_eof variable on v14, I didn't encounter any
> >> regression. I really don't understand why this is happening on my end.
> >> Manni didn't encounter any regression on the benchmark [1].
> >
> > Problem might be related to gcc. I am using Debian Trixie and my
> > current gcc version is 'gcc version 14.2.0 (Debian 14.2.0-19)'. If I
> > compile Postgres with 'Debian clang version 19.1.7 (3+b1)', then there
> > is no regression, which makes more sense IMO.
>
> Let's just re-add the temporary variable for hit_eof. The struct idea is
> clever, but it's just a little more complicated than I think is necessary
> here.
>
> I've also removed the goto in favor of just duplicating the "out" code,
> like you had before. I'd like to avoid sporadic #ifndef USE_NO_SIMD uses,
> and goto is out of fashion, anyway.

Thanks! v17 LGTM. I didn't encounter any regressions.

--
Regards,
Nazir Bilal Yavuz
Microsoft