From 17cc7f57a405417c72189b27e073a1f71faab372 Mon Sep 17 00:00:00 2001 From: John Naylor Date: Wed, 1 Jul 2026 08:50:08 +0700 Subject: [PATCH] Document wal_compression=on Commit 4035cd5d4 added LZ4 compression for full-page writes in WAL, and retained "on" as a backward-compatible way to specify the builtin PGLZ method. Document this meaning of "on" and update postgresql.conf.sample to make the equivalence clear. Author: Christoph Berg Reviewed-by: Michael Paquier Discussion: https://postgr.es/m/akJDHRtXwGLTppsQ@msg.df7cb.de Backpatch-through: 15 --- doc/src/sgml/config.sgml | 1 + src/backend/utils/misc/postgresql.conf.sample | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index cd0c4fa084c..ba51ac2cecf 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3312,6 +3312,7 @@ include_dir 'conf.d' was compiled with ) and zstd (if PostgreSQL was compiled with ). + The value on is a historical spelling of pglz. The default value is off. Only superusers and users with the appropriate SET privilege can change this setting. diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index c8ffcdf7b16..172d70051f0 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -231,7 +231,7 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz, lz4, zstd, or on + # off, pglz (or "on"), lz4, or zstd #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers