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Re: ICU for global collation

Daniel Verite <daniel@manitou-mail.org>

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From: "Daniel Verite" <daniel@manitou-mail.org>
To: "Julien Rouhaud" <rjuju123@gmail.com>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Pgsql-Hackers <pgsql-hackers@postgresql.org>
Date: 2022-03-15T19:48:00Z
Lists: pgsql-hackers 
	Julien Rouhaud wrote:

> > > While on that topic, the doc should probably mention that default ICU
> > > collations can only be deterministic.
> >
> > Well, there is no option to do otherwise, so I'm not sure where/how to
> > mention that.  We usually don't document options that don't exist. ;-)
> 
> Sure, but I'm afraid that users may still be tempted to use ICU locales like
> und-u-ks-level2 from the case_insensitive example in the doc and hope that
> it will work accordingly.

+1.

The CREATE DATABASE doc says this currently:

icu_locale

    Specifies the ICU locale ID if the ICU locale provider is used.


ISTM that we need to say explicitly that this locale will be used by
default to compare all collatable strings, except that it's overruled
by a bytewise comparison to break ties in case of equality.

The idea is to describe what the backend will do with the setting
rather than saying that we don't have a nondeterministic option.


Best regards,
-- 
Daniel Vérité
https://postgresql.verite.pro/
Twitter: @DanielVerite

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add CHECK_FOR_INTERRUPTS while restoring changes during decoding.

  2. Improve ICU option handling in CREATE DATABASE

  3. Don't allow creation of database with ICU locale with unsupported encoding

  4. Make locale option behavior more consistent

  5. pg_dump: Dump colliculocale

  6. Remove further unwanted linker flags from perl_embed_ldflags

  7. Doc: document possible need to raise kernel's somaxconn limit.

  8. Reduce warnings with -Wshadow=compatible-local builds

  9. Remove redundant spaces in _outA_Expr() output

  10. Fix outdated --help message for postgres -f

  11. pg_upgrade: Fix version comparison for global ICU support

  12. Silence -Wmaybe-uninitialized compiler warning in dbcommands.c.

  13. Add option to use ICU as global locale provider

  14. DefineCollation() code cleanup

  15. Change collate and ctype fields to type text

  16. Call pg_newlocale_from_collation() also with default collation

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

  18. Silence -Wmaybe-uninitialized compiler warnings in dbcommands.c.

  19. Make LC_COLLATE and LC_CTYPE database-level settings. Collation and