From a7cc52370b2b8a0f9883e299cb07f56d702b58c2 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Fri, 29 Mar 2019 23:00:51 +0900 Subject: [PATCH] Reorganize Notes section in documentation of pg_checksums This commit reorders the paragraphs of the Notes section in order of importance, and clarifies better the safe uses of pg_checksums for replication setups. Author: Fabien Coelho Discussion: https://postgr.es/m/alpine.DEB.2.21.1903231404280.18811@lancre --- doc/src/sgml/ref/pg_checksums.sgml | 38 ++++++++++++++---------------- 1 file changed, 18 insertions(+), 20 deletions(-) diff --git a/doc/src/sgml/ref/pg_checksums.sgml b/doc/src/sgml/ref/pg_checksums.sgml index 1f4d4ab8b4..70339eaec9 100644 --- a/doc/src/sgml/ref/pg_checksums.sgml +++ b/doc/src/sgml/ref/pg_checksums.sgml @@ -179,29 +179,27 @@ PostgreSQL documentation Notes - When disabling or enabling checksums in a replication setup of multiple - clusters, it is recommended to stop all the clusters before doing - the switch to all the clusters consistently. When using a replication - setup with tools which perform direct copies of relation file blocks - (for example ), enabling or disabling - checksums can lead to page corruptions in the shape of incorrect - checksums if the operation is not done consistently across all nodes. - Destroying all the standbys in the setup first, enabling or disabling - checksums on the primary and finally recreating the standbys from - scratch is also safe. + Enabling checksums in a large cluster can potentially take a long time. + During this operation, the cluster or other programs that write to the + data directory must not be started or else data loss may occur. - If pg_checksums is aborted or killed in - its operation while enabling or disabling checksums, the cluster - will have the same state with respect of checksums as before the - operation and pg_checksums needs to be - restarted. + When using a replication setup with tools which perform direct copies + of relation file blocks (for example ), + enabling or disabling checksums can lead to page corruptions in the + shape of incorrect checksums if the operation is not done consistently + across all nodes. When enabling or disabling checksums in a replication + setup, it is thus recommended to stop all the clusters before switching + them all consistently. Destroying all standbys, performing the operation + on the primary and finally recreating the standbys from scratch is also + safe. - When enabling checksums in a cluster, the operation can potentially - take a long time if the data directory is large. During this operation, - the cluster or other programs that write to the data directory must not - be started or else data loss may occur. - + If pg_checksums is aborted or killed while + enabling or disabling checksums, the cluster will keep the same + configuration for data checksums as before the operation attempted. + pg_checksums can be restarted to + attempt again the same operation. + -- 2.40.0