Horton

Re: Collation versioning

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Christoph Berg <myon@debian.org>, Thomas Munro <thomas.munro@enterprisedb.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-09-13T07:03:40Z
Lists: pgsql-hackers 
On 12/09/2018 13:25, Christoph Berg wrote:
> Re: Peter Eisentraut 2018-09-12 <0447ec7b-cdb6-7252-7943-88a4664e7bb7@2ndquadrant.com>
>>> Naive idea: make that catalog shared? Collations are system-wide after
>>> all.
>>
>> By the same argument, extensions should be shared, but they are not.
> 
> But extensions put a lot of visible stuff into a database, whereas a
> collation is just a line in some table that doesn't get into the way.

How about C functions?  They are just a system catalog representation of
something that exists on the OS.

Anyway, we also want to support application-specific collation
definitions, so that users can CREATE COLLATION
"my_specific_requirements" and use that that in their application, so
global collations wouldn't be appropriate for that.

Moreover, the fix for a collation version mismatch is, in the simplest
case, to go around and REINDEX everything.  Making the collation or
collation version global doesn't fix that.  It would actually make it
harder because you couldn't run ALTER COLLATION REFRESH VERSION until
after you have rebuilt all affected objects *in all databases*.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.