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| author | Thomas Munro <tmunro@postgresql.org> | 2021-05-07 21:47:08 +1200 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2021-05-07 21:58:02 +1200 |
| commit | b65431ca5e12a475ba7cf68afb63edb070c2ce08 (patch) | |
| tree | eb2d7872ad893fbce88c03ccdc0e92fe8801aa39 | |
| parent | ec48314708262d8ea6cdcb83f803fc83dd89e721 (diff) | |
| download | postgresql-b65431ca5e12a475ba7cf68afb63edb070c2ce08.tar.gz postgresql-b65431ca5e12a475ba7cf68afb63edb070c2ce08.zip | |
Doc: Update notes about libc collation versions.
The per-index collation version tracking feature was reverted, but we
still have the ability to ask Windows (352f6f2d) and FreeBSD
(ca051d8b) for collation versions to store in pg_collation.collversion.
So, from the reverted patch, take a few words of documentation about
libc on all three supported OSes to replace the pre-existing note that
mentioned only glibc.
Discussion: https://postgr.es/m/CA%2BhUKGLhj5t1fcjqAu8iD9B3ixJtsTNqyCCD4V0aTO9kAKAjjA%40mail.gmail.com
| -rw-r--r-- | doc/src/sgml/ref/alter_collation.sgml | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/doc/src/sgml/ref/alter_collation.sgml b/doc/src/sgml/ref/alter_collation.sgml index af9ff2867b7..9bcb91e8ff9 100644 --- a/doc/src/sgml/ref/alter_collation.sgml +++ b/doc/src/sgml/ref/alter_collation.sgml @@ -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> |