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Date: Tue, 28 Jun 2016 18:20:11 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
	PostgreSQL-documentation <pgsql-docs@postgresql.org>
Subject: Re: Pg_upgrade and collation
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On Tue, Jun 28, 2016 at 02:58:58PM -0700, Peter Geoghegan wrote:
> On Fri, Jun 17, 2016 at 2:51 PM, Alvaro Herrera
> <alvherre@2ndquadrant.com> wrote:
> > I think this is way too thin to be helpful:
> >
> >> --- 61,68 ----
> >>     checking for compatible compile-time settings, including 32/64-bit
> >>     binaries.  It is important that
> >>     any external modules are also binary compatible, though this cannot
> >> !   be checked by <application>pg_upgrade</>.  Compatible collation
> >> !   library versions must also be used.
> >>    </para>
> 
> Unfortunately, the reality is that as things stand, there is no way to
> test compatibility on all platforms. Glibc does have a notion of
> collation versioning, though [1].

Yes, the patch text is clearly weasel-words in that we can't explain how
to detect incompatible.

> I have long advocated adopting ICU as our defacto standard "collation
> provider", primarily so that we can directly control collations and
> collation versioning. I think that doing this would solve many
> problems. Besides, even SQLite has optional ICU support. PostgreSQL is
> the only major database system that I'm aware of that relies on
> operating system collations exclusively.

I am hopeful ICU has improved enough since we last researched that
support for it will soon be added.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+                     Ancient Roman grave inscription +


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