MIME-Version: 1.0
References: <20231009230805.funj5ipoggjyzjz6@awork3.anarazel.de>
 <E25A9AD2-EAD3-4372-AFD2-2627E4D5E3C5@percona.com> <x56pxq6jpuftn6ear3uwbz5tyb4r37itv5zetvcucq3td57apc@yq7jyka7tszv>
 <CA+aWR11Gvz4RvPaBx1kfpTx2QxpNW46Yv120dDcUA93UbYcxrg@mail.gmail.com>
In-Reply-To: <CA+aWR11Gvz4RvPaBx1kfpTx2QxpNW46Yv120dDcUA93UbYcxrg@mail.gmail.com>
From: Andy Pogrebnoi <andrew.pogrebnoi@percona.com>
Date: Wed, 18 Feb 2026 15:26:24 +0200
Message-ID: <CA+aWR11mKA=kFGxX++6uMAhhqzRPU72ktd9TnhbD3O8OnR_Org@mail.gmail.com>
Subject: Re: Lowering the default wal_blocksize to 4K
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org, Heikki Linnakangas <hlinnaka@iki.fi>, 
	Robert Haas <robertmhaas@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, 
	Matthias van de Meent <boekewurm+postgres@gmail.com>
Content-Type: multipart/alternative; boundary="000000000000115113064b1923a7"
Archived-At: <https://www.postgresql.org/message-id/CA%2BaWR11mKA%3DkFGxX%2B%2B6uMAhhqzRPU72ktd9TnhbD3O8OnR_Org%40mail.gmail.com>
Precedence: bulk

--000000000000115113064b1923a7
Content-Type: text/plain; charset="UTF-8"

Hi,

The Windows tests are failing on `Assert("check_GUC_init(hentry->gucvar)")`
for wal_writer_flush_after [1]. It doesn't make much sense to me as both
load- and C-value for the wal_writer_flush_after GUC are the same constant:

src/backend/utils/misc/guc_parameters.dat:
{ name => 'wal_writer_flush_after', type => 'int', context => 'PGC_SIGHUP',
group => 'WAL_SETTINGS',
  short_desc => 'Amount of WAL written out by WAL writer that triggers a
flush.',
  flags => 'GUC_UNIT_XBLOCKS',
  variable => 'WalWriterFlushAfter',
  boot_val => 'DEFAULT_WAL_WRITER_FLUSH_AFTER',
  min => '0',
  max => 'INT_MAX',
},

src/include/postmaster/walwriter.h:
int WalWriterFlushAfter = DEFAULT_WAL_WRITER_FLUSH_AFTER;

This constant was introduced to fix the same issue [2], but I suppose no
one checked Windows builds. Windows clearly has an old 8kB value for
WalWriterFlushAfter during the check. I suppose it is something with the
CI/build. But I have zero experience with building anything for Windows, so
any tips on where to look are welcome.

*And apologies for the dreadful formatting in my previous email; the client
plays tricks on me after I hit Send.

[1] https://cirrus-ci.com/task/6286650038288384?logs=test_world#L2728-L2729
[2]
https://www.postgresql.org/message-id/CA+hUKGLNmLV=VrT==5MqnbARgx2ifRSFtdd8ofdfrdSLL3yv5A@mail.gmail.com

---
Cheers,
Andy

--000000000000115113064b1923a7
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div dir=3D"ltr">Hi,<br><br>The Windows tests are failing =
on `Assert(&quot;check_GUC_init(hentry-&gt;gucvar)&quot;)` for wal_writer_f=
lush_after [1]. It doesn&#39;t make much sense to me as both load- and C-va=
lue for the wal_writer_flush_after GUC are the same constant:<br><br>src/ba=
ckend/utils/misc/guc_parameters.dat:<br>{ name =3D&gt; &#39;wal_writer_flus=
h_after&#39;, type =3D&gt; &#39;int&#39;, context =3D&gt; &#39;PGC_SIGHUP&#=
39;, group =3D&gt; &#39;WAL_SETTINGS&#39;,<br>=C2=A0 short_desc =3D&gt; =
9;Amount of WAL written out by WAL writer that triggers a flush.&#39;,<br>=
=C2=A0 flags =3D&gt; &#39;GUC_UNIT_XBLOCKS&#39;,<br>=C2=A0 variable =3D&gt;=
 &#39;WalWriterFlushAfter&#39;,<br>=C2=A0 boot_val =3D&gt; &#39;DEFAULT_WAL=
_WRITER_FLUSH_AFTER&#39;,<br>=C2=A0 min =3D&gt; &#39;0&#39;,<br>=C2=A0 max =
=3D&gt; &#39;INT_MAX&#39;,<br>},<br><br>src/include/postmaster/walwriter.h:=
<br>int			WalWriterFlushAfter =3D DEFAULT_WAL_WRITER_FLUSH_AFTER;<br><br>Th=
is constant was introduced to fix the same issue [2], but I suppose no one =
checked Windows builds. Windows clearly has an old 8kB value for WalWriterF=
lushAfter during the check. I suppose it is something with the CI/build. Bu=
t I have zero experience with building anything for Windows, so any tips on=
 where to look are welcome.<br><br>*And apologies for the dreadful formatti=
ng in my previous email; the client plays tricks on me after I hit Send.<br=
><br>[1] <a href=3D"https://cirrus-ci.com/task/6286650038288384?logs=3Dtest=
_world#L2728-L2729">https://cirrus-ci.com/task/6286650038288384?logs=3Dtest=
_world#L2728-L2729</a><br>[2] <a href=3D"https://www.postgresql.org/message=
-id/CA+hUKGLNmLV=3DVrT=3D=3D5MqnbARgx2ifRSFtdd8ofdfrdSLL3yv5A@mail.gmail.co=
m">https://www.postgresql.org/message-id/CA+hUKGLNmLV=3DVrT=3D=3D5MqnbARgx2=
ifRSFtdd8ofdfrdSLL3yv5A@mail.gmail.com</a><br><br>---<br>Cheers,<br>Andy<br=
></div>
</div>

--000000000000115113064b1923a7--