MIME-Version: 1.0
References: <CAN55FZ3g6QaiC8G4GMjdJ24egvgc-HG_xpoOztxnM_wnQNn5aw@mail.gmail.com>
 <aY-vJe_ENCB-fux9@nathan> <CAN55FZ2OpqRxUUEvgPpHCk2HnY0xZSH1x09fgFGOUyXSv8HcEA@mail.gmail.com>
 <aZYudtuBLVb36pZE@nathan> <CAN55FZ0J5iz9wFJLHcK7yNQqPb10_4ROoZiDu1wBZWSGC_fATg@mail.gmail.com>
 <CAKWEB6qY=mU62oAQFAVPCFWvwRuTPKBwxvM2aZ+J7p_9_MBmhQ@mail.gmail.com>
 <CAN55FZ2RPMxquXE6TH7dQkhtoiBcOOOZq8EOXj5COHv3ecP_cw@mail.gmail.com>
 <CA+K2Ru=fFTUVgEDr-fBed5aOMeDbH9vrOEhapXzHEpBeOxkucg@mail.gmail.com>
 <CAKWEB6pq7C0Wv1wT9Y1_c_1fn-+cR8pb210Pj3w2FcEOmNGxbQ@mail.gmail.com>
 <CAN55FZ2DT4-k06umn=7NYG+NoM6gnVJVQCCwRrr2qOraO+Jadw@mail.gmail.com>
 <aZikzQP6WPJ5Rq2S@nathan> <CAN55FZ3cBN_TncLVWyXAKm-KfewguN1AUjyRhoR6zL_QCxHh7A@mail.gmail.com>
 <CAKWEB6qzsZEQ4Czo9QBFiMXqdXVJknHUJwg6wjRwNzLn4+Jw0g@mail.gmail.com>
In-Reply-To: <CAKWEB6qzsZEQ4Czo9QBFiMXqdXVJknHUJwg6wjRwNzLn4+Jw0g@mail.gmail.com>
From: Nazir Bilal Yavuz <byavuz81@gmail.com>
Date: Tue, 24 Feb 2026 16:57:21 +0300
Message-ID: <CAN55FZ2O2Ls==sdpROHqxWRx-PMBZ0riJ6eVKoHj8=vssTavxw@mail.gmail.com>
Subject: Re: Speed up COPY FROM text/CSV parsing using SIMD
To: Manni Wood <manni.wood@enterprisedb.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, KAZAR Ayoub <ma_kazar@esi.dz>, 
	Neil Conway <neil.conway@gmail.com>, Andrew Dunstan <andrew@dunslane.net>, 
	Shinya Kato <shinya11.kato@gmail.com>, 
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://www.postgresql.org/message-id/CAN55FZ2O2Ls%3D%3DsdpROHqxWRx-PMBZ0riJ6eVKoHj8%3DvssTavxw%40mail.gmail.com>
Precedence: bulk

Hi,

On Tue, 24 Feb 2026 at 07:44, Manni Wood <manni.wood@enterprisedb.com> wrot=
e:
>
> Hello!
>
> I ran some speed tests on Nazir's v10 SIMD-only patch. I'm a bit surprise=
d 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 numbe=
rs 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%3DA2uTHpywczq=
t%3D-Q%40mail.gmail.com

--
Regards,
Nazir Bilal Yavuz
Microsoft