From 0660ead78d62660fa97e20fd101464762d081553 Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Mon, 13 Jul 2026 13:47:20 +0200 Subject: [PATCH v5 1/2] Mention checkpoints in online data checksums docs Mention checkpoints in the docs discussion impact of online data checksums changes on the system. Checkpoints (especially fast ones) are a major source of write activity, and can be rather disruptive. Backpatch to 19, where the online change of data checksums was introduced. Author: Tomas Vondra Discussion: https://postgr.es/m/37745926-4213-49a3-b628-4136e9e49f9b@vondra.me Backpatch-through: 19 --- doc/src/sgml/wal.sgml | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 646076f7e39..1adfca01aa5 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -357,12 +357,19 @@ parameters of the pg_enable_data_checksums() function. + + Checkpoints have to be performed at certain points - both when enabling + and disabling data checksums, which may generate of lot of writes due to + flushing dirty pages. + + I/O: all pages need to have data checksums calculated and written which will generate a lot of dirty pages that will need to be flushed to disk, - as well as WAL logged. + as well as WAL logged. Both enabling and disabling data checksums requires + performing checkpoints, which may generate a lot of writes. Replication: When the standby receives the data checksum state change -- 2.54.0