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doc: Improve description of wal_compression

author Michael Paquier <michael@paquier.xyz>

2025年8月21日 04:25:03 +0000 (13:25 +0900)

committer Michael Paquier <michael@paquier.xyz>

2025年8月21日 04:25:03 +0000 (13:25 +0900)

The description of this GUC provides a list of the situations where
full-page writes are generated. However, it is not completely exact,
mentioning only the cases where full_page_writes=on or base backups. It
is possible to generate full-page writes in more situations than these
two, making the description confusing as it implies that no other cases
exist.

The description is slightly reworded to take into account that other
cases are possible, without mentioning them directly to minimize the
maintenance burden should FPWs be generated in more contexts in the
future.

Author: Jingtang Zhang <mrdrivingduck@gmail.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
Discussion: https://postgr.es/m/CAPsk3_CtAYa_fy4p6=x7qtoutrdKvg1kGk46D5fsE=sMt2546g@mail.gmail.com
Backpatch-through: 13

doc/src/sgml/config.sgml patch | blob | blame | history

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml

index 20ccb2d6b5447ca4dcc8f23bb5ff88d8f94cd37b..0a4b3e55ba5ed2784f0dda8b2903e725e1dce33f 100644 (file)

--- a/doc/src/sgml/config.sgml

+++ b/doc/src/sgml/config.sgml

@@ -3399,8 +3399,9 @@ include_dir 'conf.d'

This parameter enables compression of WAL using the specified

compression method.

When enabled, the <productname>PostgreSQL</productname>

- server compresses full page images written to WAL when

- <xref linkend="guc-full-page-writes"/> is on or during a base backup.

+ server compresses full page images written to WAL (e.g. when

+ <xref linkend="guc-full-page-writes"/> is on, during a base backup,

+ etc.).

A compressed page image will be decompressed during WAL replay.

The supported methods are <literal>pglz</literal>,

<literal>lz4</literal> (if <productname>PostgreSQL</productname>

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