Re: pgsql: doc: mention dependency on collation libraries

On Thu, Jul 21, 2016 at 09:59:42AM +0200, Christoph Berg wrote:
> Re: Bruce Momjian 2016-07-20 <20160720161318.GE24559@momjian.us>
> > > > How about simply this: ?
> > > >
> > > >    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
> > > > eason,
> > > >    a cluster cannot switch to an incompatible collation library
> > > > ersion,
> > > >    either through
> > > >
> > > > +  operating system upgrade,
> > > >
> > > >    snapshot restore, binary streaming replication, or
> > > >    <application>pg_upgrade</> run.
> > >
> > > OK, good point.  I was more focused on cluster moves than an OS change.
> > > How is the attached patch?
> >
> > With the mention of different operating systems, there is no need to
> > mention pg_upgrade anymore as it is already covered.  Updated patch
> > attached.
>
> With that argument, you could drop snapshot restore and replication as
> well, as "different OS (version)" is the real problem. Still,
> mentioning pg_upgrade would highlight the fact that it doesn't "fix"
> the problem in the same sense that pg_dump would. Collation changes
> are subtle changes that are surprising in many cases, so mention a few
> cases makes people aware more.

I mentioned snapshot restore and replication as a way to highlight that
it is binary transfer that is the problem, not pg_dump.

You are right about pg_upgrade not fixing the problem, but since it only
runs on the same machine, I don't see it as a good example.

--
  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. +
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