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

Hello,

On Tue, Feb 24, 2026 at 2:57 PM Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
wrote:

> Hi,
>
> On Tue, 24 Feb 2026 at 07:44, Manni Wood <manni(dot)wood(at)enterprisedb(dot)com>
> wrote:
> >
> > Hello!
> >
> > I ran some speed tests on Nazir's v10 SIMD-only patch. I'm a bit
> surprised at the regression for x86 with wide rows for the 1/3rd special
> characters scenarios. I'm hoping it's something I did wrong. If anyone else
> has numbers to share, that would be excellent.
>
> Thank you for doing this!
>
> I see similar regression on the wide & CSV 1/3 case by using your
> benchmark script. I didn't see this regression when I used my
> benchmark while sharing v9 [1].
>
> +-------------+---------------------------+---------------------------+
> | | Text | CSV |
> +-------------+-------------+-------------+-------------+-------------+
> | WIDE TEST | None | 1/3 | None | 1/3 |
> +-------------+-------------+-------------+-------------+-------------+
> | Master | 9996 | 10769 | 11548 | 13960 |
> +-------------+-------------+-------------+-------------+-------------+
> | v10 | 8912 %-10.8 | 10902 %+1.2 | 8952 %-22.4 | 15123 %+8.3 |
> +-------------+-------------+-------------+-------------+-------------+
> | | | | | |
> +-------------+-------------+-------------+-------------+-------------+
> | | Text | | CSV |
> +-------------+-------------+-------------+-------------+-------------+
> | NARROW TEST | None | 1/3 | None | 1/3 |
> +-------------+-------------+-------------+-------------+-------------+
> | Master | 9441 | 9561 | 9734 | 9830 |
> +-------------+-------------+-------------+-------------+-------------+
> | v10 | 9291 %-1.5 | 9504 -%0.5 | 9644 %-0.9 | 10078 %-2.4 |
> +-------------+-------------+-------------+-------------+-------------+
>
> I will investigate this. However, please note that the current master
> includes the inlining commit (dc592a4155), which makes the COPY FROM
> faster. In my case,
>
> 1: current master without dc592a4155: 14400ms
> 2: current master: 13960ms (%3 improvement against #1)
> 3: current master + SIMD: 15123ms (%5 regression against #1 and %8
> regression against #2)
>
> Is it possible for you to do a similar test? I mean dropping
> dc592a4155 from the current master and re-running the benchmark, that
> would be helpful.
>
> [1]
> https://postgr.es/m/CAN55FZ0MiFCgK26gRgE05a%3D_ggenkxDM8H%3DA2uTHpywczqt%3D-Q%40mail.gmail.com

Here are some numbers for v10 from my end, these are multiple long runs:
Master contains the previous inlining patch.

This is on an Intel I7-1255U CPU

WIDE (500k rows)

TXT | none
Master avg: 20,721 ms
New avg: 17,980 ms
Improvement: -13.23%

CSV | none
Master avg: 26,608 ms
New avg: 18,433 ms
Improvement: -30.73%

TXT | escape
Master avg: 25,069 ms
New avg: 22,910 ms
Improvement: -8.61%

CSV | quote
Master avg: 31,931 ms
New avg: 31,493 ms
Improvement: -1.37%

--------------------------------------

NARROW (15M rows)

TXT | none
Master avg: 20,687 ms
New avg: 20,824 ms
Regression: +0.67%

CSV | none
Master avg: 21,187 ms
New avg: 21,153 ms
Improvement: -0.16%

TXT | escape
Master avg: 20,870 ms
New avg: 21,341 ms
Regression: +2.25%

CSV | quote
Master avg: 22,074 ms
New avg: 22,267 ms
Regression: +0.87%

For narrow that would be mostly noise and extra branch effects.

Regards,
Ayoub