On Wed, 2021-06-02 at 18:16 +0900, Masahiko Sawada wrote:
> > > We should add a line that indicates that there is a limitation (that
> > > should be IMO, backported to documentation of earlier versions as it
> > > affects all supported versions), at least until such limitation is
> > > lifted.
> > Here is a patch for that,
>
> The patch adds the description in the autovacuum_work_mem section.
> Isn't it better to add it in mantenance_work section or VACUUM command
> section since this limitation is not only for autovacuum?
You are right; theoretically, the correct place to document that
would be the VACUUM documentation. But I guess that most people who
are curious about VACUUM's memory usage will read the documentation for
"maintenance_work_mem" or "autovacuum_work_mem".
I have fixed a typo and added a similar paragraph to "maintenance_work_mem".
Yours,
Laurenz Albe
From a94811e45df96846cb0531615e9d773f69d2cc2d Mon Sep 17 00:00:00 2001
From: Laurenz Albe <laurenz.a...@cybertec.at>
Date: Fri, 4 Jun 2021 14:30:08 +0200
Subject: [PATCH] Document the 1GB memory limit for VACUUM
---
doc/src/sgml/config.sgml | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 7e32b0686c..0976494506 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1882,6 +1882,12 @@ include_dir 'conf.d'
too high. It may be useful to control for this by separately
setting <xref linkend="guc-autovacuum-work-mem"/>.
</para>
+ <para>
+ Also, note that <command>VACUUM</command> has a hard-coded limit of 1GB
+ for the amount of memory used, so setting
+ <varname>maintenance_work_mem</varname> higher than that has no effect
+ as far as <command>VACUUM</command> is concerned.
+ </para>
</listitem>
</varlistentry>
@@ -1901,6 +1907,11 @@ include_dir 'conf.d'
be used instead. The setting has no effect on the behavior of
<command>VACUUM</command> when run in other contexts.
</para>
+ <para>
+ Note that <command>VACUUM</command> has a hard-coded limit of 1GB
+ for the amount of memory used, so setting
+ <varname>autovacuum_work_mem</varname> higher than that has no effect.
+ </para>
</listitem>
</varlistentry>
--
2.26.3
