index af9ff2867b72234f94e2bf52b0def1086acb6c48..9bcb91e8ff9b76e688b4645e6e5b1bba4ddf7185 100644 (file)
@@ -129,12 +129,24 @@ HINT: Rebuild all objects affected by this collation and run ALTER COLLATION pg
correctly.
</para>
<para>
- When using collations provided by <literal>libc</literal> and
- <productname>PostgreSQL</productname> was built with the GNU C library, the
- C library's version is used as a collation version. Since collation
- definitions typically change only with GNU C library releases, this provides
- some defense against corruption, but it is not completely reliable.
+ When using collations provided by <literal>libc</literal>, version
+ information is recorded on systems using the GNU C library (most Linux
+ systems), FreeBSD and Windows.
</para>
+ <note>
+ <para>
+ When using the GNU C library for collations, the C library's version
+ is used as a proxy for the collation version. Many Linux distributions
+ change collation definitions only when upgrading the C library, but this
+ approach is imperfect as maintainers are free to back-port newer
+ collation definitions to older C library releases.
+ </para>
+ <para>
+ When using Windows for collations, version information is only available
+ for collations defined with BCP 47 language tags such as
+ <literal>en-US</literal>.
+ </para>
+ </note>
<para>
Currently, there is no version tracking for the database default collation.
</para>