Date: Thu, 26 Mar 2026 16:09:23 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: KAZAR Ayoub <ma_kazar@esi.dz>
Cc: Andres Freund <andres@anarazel.de>,
	Pg Hackers <pgsql-hackers@postgresql.org>,
	Neil Conway <neil.conway@gmail.com>,
	Manni Wood <manni.wood@enterprisedb.com>,
	Andrew Dunstan <andrew@dunslane.net>,
	Shinya Kato <shinya11.kato@gmail.com>,
	Mark Wong <markwkm@gmail.com>,
	Nazir Bilal Yavuz <byavuz81@gmail.com>
Subject: Re: Speed up COPY TO text/CSV parsing using SIMD
Message-ID: <acWgg0cG7MALI2hB@nathan>
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On Wed, Mar 18, 2026 at 12:02:28AM +0100, KAZAR Ayoub wrote:
>   Test                 Master    v3       v3_var   v3_var_noinl
>   TEXT clean           1504ms   -24.1%   -23.0%   -21.5%
>   CSV clean            1760ms   -34.9%   -32.7%   -33.0%

Nice!

>   TEXT 1/3 backslashes     3763ms    +4.6%    +6.9%   +4.1%
>   CSV 1/3 quotes           3885ms    +3.1%    +2.7%    -0.8%

Hm.  These seem a little bit beyond what we could ignore as noise.

> Wide table TEXT (integer columns):
> 
>   Cols    Master    v3       v3_var   v3_var_noinl
>   50      2083ms   -0.7%    -0.6%    +3.5%
>   100     4094ms   -0.1%    -0.5%    +4.5%
>   200     1560ms   +0.6%    -2.3%    +3.2%
>   500     1905ms   -1.0%    -1.3%    +4.7%
>   1000    1455ms   +1.8%    +0.4%    +4.3%

These numbers look roughly within the noise range.

> Wide table CSV:
> 
>   Cols    Master    v3       v3_var   v3_var_noinl
>   50      2421ms   +4.0%    +6.7%    +5.8%

Hm.  Is this reproducible?  A 4% regression is a bit worrisome.

>   100     4980ms   +0.1%    +2.0%     +0.1%
>   200     1901ms   +1.4%    +3.5%    +1.4%
>   500     2328ms   +1.8%    +2.7%    +2.2%
>   1000    1815ms   +2.0%    +2.8%    +2.5%

These numbers don't bother me too much, but maybe there are some ways to
minimize the regressions further.

-- 
nathan