MIME-Version: 1.0
References: <aZ3kYQnF9_u6sUQp@nathan>
 <CAN55FZ3+NYF1TkKyNtpRQuLiaauSYk9G5tA+fpruOA4-14Y_ZA@mail.gmail.com>
 <aaXrGSyq4u2d9qEC@nathan>
 <CAN55FZ2DNaKCK3Kf_kHizb2pAbQvULeDYtzaiz97B_xz7YbrkQ@mail.gmail.com>
 <91acb778-42c4-44ef-8888-f18ad9b12a5b@dunslane.net>
 <CAKWEB6r0CrN-a2P=2ey3EK7p1MxsbQx2C8=hpNGfxLxnRaX66Q@mail.gmail.com>
 <CAN55FZ1BYbdt97RLkd-vAVZ5EKiX=KLkhJ_S-4vgvNJRHvQZ6w@mail.gmail.com>
 <CAKWEB6pmXvv3sbQBNLAR_B=8wzX8rn4VFsJ4WwmNbuJ2etSwDQ@mail.gmail.com>
 <CAN55FZ25HV0FNziFR8xBpQpHkNPS48w8yEXCc91W+=0c0jr+KA@mail.gmail.com>
 <CAKWEB6rnMKYGSt=t9=pL2kKUefsAdzKfjtwdqW_acv1+vMTKVA@mail.gmail.com>
 <aatfiTMLvLok2cUc@nathan>
 <CA+K2RunT=1P7_E4jrZMogDiPunNCOGw9P_UHLaJRJk=5_odKmA@mail.gmail.com>
 <CAN55FZ1k2sOZn1qkDDVTX8Z1t99ZUkywBhdp_43euDHaAi5bRA@mail.gmail.com>
 <CAKWEB6pJ-5b7QUmVtG12hC0bQ82OvDv4XsidAcnngN36q28qTQ@mail.gmail.com>
 <CAN55FZ1pM3PgKfAuTT5YmG4enCoh93bOjxNi95nqKgwbHmh3hg@mail.gmail.com>
 <CAKWEB6pWU+2mUa41t0Tb+3XmKyDuGSS=8XaDirumjSc9=d8WJQ@mail.gmail.com>
In-Reply-To: 
 <CAKWEB6pWU+2mUa41t0Tb+3XmKyDuGSS=8XaDirumjSc9=d8WJQ@mail.gmail.com>
From: Nazir Bilal Yavuz <byavuz81@gmail.com>
Date: Mon, 9 Mar 2026 16:43:00 +0300
Message-ID: 
 <CAN55FZ0sgNGT5AmGd1Pv3Wu--uUE1jSugh2REqNa4d55KdPvAw@mail.gmail.com>
Subject: Re: Speed up COPY FROM text/CSV parsing using SIMD
To: Manni Wood <manni.wood@enterprisedb.com>
Cc: KAZAR Ayoub <ma_kazar@esi.dz>, Nathan Bossart <nathandbossart@gmail.com>,
	Andrew Dunstan <andrew@dunslane.net>, Neil Conway <neil.conway@gmail.com>,
	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/CAN55FZ0sgNGT5AmGd1Pv3Wu--uUE1jSugh2REqNa4d55KdPvAw%40mail.gmail.com>
Precedence: bulk

Hi Manni!

On Mon, 9 Mar 2026 at 16:31, Manni Wood <manni.wood@enterprisedb.com> wrote=
:
>
> I was being too brief.
>
> The benchmarks I shared were absolutely with lz4 compiled in and 'default=
_toast_compression =3D lz4' set in postgresql.conf for every postgres insta=
nce I tested with. (Furthermore, I ran `show default_toast_compression` via=
 `psql` on each postgres instance to be sure 'default_toast_compression =3D=
 lz4' was really set!)
>
> Also, all were compiled using meson using `debugoptimized` which results =
in `-g -O2`.
>
> So those are the benchmarks that I shared.

Thanks for the clarification.

> OK, so my final question, hopefully clarified: If I run additional benchm=
arks where pglz is used for default_toast_compression, is it enough to use =
the instances I have already compiled with lz4 in them, but with 'default_t=
oast_compression =3D pglz` explicitly set in postgresql.conf in a brand new=
 data dir created by initdb? (In other words, existing data dir deleted, th=
en initdb run to make a new data dir, then postgresql.conf edited to ensure=
 'default_toast_compression =3D pglz` explicitly set, then and only then st=
arting up the cluster for the first time... and finally verifying via `show=
 default_toast_compression` for good measure.)
>
> Or should I re-compile with the lz4-is-now-the-default commit completely =
excised?

Yes, it is clear now; thanks. You don't need to compile without the
lz4-is-now-the-default commit. You can compile with lz4 commit and set
the 'default_toast_compression =3D pglz' in the postgresql.conf like you
said. This should be enough.

--=20
Regards,
Nazir Bilal Yavuz
Microsoft