Horton

Re: Collation versioning

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Michael Paquier <michael@paquier.xyz>, Julien Rouhaud <rjuju123@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Douglas Doole <dougdoole@gmail.com>, Christoph Berg <myon@debian.org>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-11-26T20:43:21Z
Lists: pgsql-hackers 
On Fri, Nov 8, 2019 at 5:40 PM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
> On Fri, 2019-11-08 at 15:04 +1300, Thomas Munro wrote:
> > 3.  We don't know if pre-13 indexes are corrupted or not, and we'll
> > record that with a special value just as in proposal #1, except that
> > we could show a different hint for that special version value.  It
> > would tell you can you can either REINDEX, or run ALTER INDEX ...
> > DEPENDS ON COLLATION "fr_FR" VERSION '34.0' if you believe the index
> > to have been created with the current collation version on an older
> > release of PostgreSQL that didn't track versions.

> #3 is the best proposal, but there is still the need to run
> ALTER INDEX on all affected indexes to keep PostgreSQL from nagging.
> Perhaps the situation could be improved with a pg_upgrade option
> --i-know-my-indexes-are-fine that causes a result like #2.
> Together with a bold note in the release notes, this may relieve
> the pain.

I suppose another reason to use such a switch would be if there is a
change in the versioning scheme; for example, as of today in master we
are using the glibc version, but a future glibc release might offer an
interface to query the CLDR version it's using, and then a future
release of PostgreSQL might get support for that, so the strings would
change between major version of PostgreSQL but you might want to be
able to tell pg_upgrade that your indexes are good.

Commits

  1. Doc: Document known problem with Windows collation versions.

  2. Add collation versions for FreeBSD.

  3. Tolerate version lookup failure for old style Windows locale names.

  4. Track collation versions for indexes.

  5. Add pg_depend.refobjversion.

  6. Remove pg_collation.collversion.

  7. Fix the MSVC build for versions 2015 and later.

  8. Add collation versions for Windows.

  9. Implement type regcollation

  10. Use libc version as a collation version on glibc systems.

  11. Make type "name" collation-aware.