From e612181686b54a0311a85247c7f1640dee53636f Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Sat, 2 Jul 2016 11:22:36 -0400
Subject: [PATCH] doc: mention dependency on collation libraries
Document that index storage is dependent on the operating system's
collation library ordering, and any change in that ordering can create
invalid indexes.
Discussion: 20160617154311.GB19359@momjian.us
Backpatch-through: 9.1
---
doc/src/sgml/runtime.sgml | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index fba67a37c79..cdc16c3ce5a 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -183,6 +183,15 @@ postgres$ <userinput>initdb -D /usr/local/pgsql/data</userinput>
locale setting. For details see <xref linkend="multibyte">.
</para>
+ <para>
+ Non<literal>C</> and and non-<literal>POSIX</> locales rely on the
+ operating system's collation library for character set ordering.
+ This controls the ordering of keys stored in indexes. For this reason,
+ a cluster cannot switch to an incompatible collation library version,
+ either through snapshot restore, binary streaming replication, or
+ <application>pg_upgrade</> run.
+ </para>
+
<sect2 id="creating-cluster-mount-points">
<title>Use of Secondary File Systems</title>