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Re: Order changes in PG16 since ICU introduction

Daniel Verite <daniel@manitou-mail.org>

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From: "Daniel Verite" <daniel@manitou-mail.org>
To: "Jeff Davis" <pgsql@j-davis.com>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Andrew Gierth <andrew@tao11.riddles.org.uk>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
Date: 2023-06-06T13:09:59Z
Lists: pgsql-hackers 
	Jeff Davis wrote:

> New patch series attached. I plan to commit 0001 and 0002 soon, unless
> there are objections.
> 
> 0001 causes the "C" and "POSIX" locales to be treated with
> memcmp/pg_ascii semantics in ICU, just like in libc. We also
> considered a new "none" provider, but it's more invasive, and we can
> always reconsider that in the v17 cycle.

FWIW I don't quite see how 0001 improve things or what problem it's
trying to solve.

0001 creates exceptions throughout the code so that when an ICU
collation has a locale name "C" or "POSIX" then it does not behave
like an ICU collation, even though pg_collation.collprovider='i'
To me it's neither desirable nor necessary that a collation that
has collprovider='i' is diverted to non-ICU semantics.

Also in the current state, this diversion does not apply to initdb.

"initdb --icu-locale=C" with 0001 applied reports this:

   Using language tag "en-US-u-va-posix" for ICU locale "C".
   The database cluster will be initialized with this locale configuration:
     provider:	  icu
     ICU locale:  en-US-u-va-posix
     LC_COLLATE:  fr_FR.UTF-8
     [...]

and "initdb --locale=C" reports this:

   Using default ICU locale "fr_FR".
   Using language tag "fr-FR" for ICU locale "fr_FR".
   The database cluster will be initialized with this locale configuration:
     provider:	  icu
     ICU locale:  fr-FR
     LC_COLLATE:  C
     [...]

Could you elaborate a bit more on what 0001 is meant to achieve, from
the point of view of the user?


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. Introduce "builtin" collation provider.

  2. ICU: do not convert locale 'C' to 'en-US-u-va-posix'.

  3. initdb: change default --locale-provider back to libc.

  4. CREATE DATABASE: make LOCALE apply to all collation providers.

  5. Remove read-only server settings lc_collate and lc_ctype

  6. ICU: use uloc_getDefault() for initdb.

  7. Doc fixes for commit 1e16af8ab5.

  8. Doc: fix some rendering problems in the PDF docs build.

  9. Doc improvements for language tags and custom ICU collations.

  10. ICU: check for U_STRING_NOT_TERMINATED_WARNING.

  11. Reduce icu_validation_level default to WARNING.

  12. Revert "ICU: do not convert locale 'C' to 'en-US-u-va-posix'."

  13. Fix initdb --no-locale.

  14. Avoid character classification in regex escape parsing.