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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: 2023-06-08T10:08:12Z
Lists: pgsql-hackers 
	Jeff Davis wrote:

> As I replied in that subthread, that creates a worse problem: if you
> only change the provider when the locale is C, then what about when the
> locale is *not* C?
> 
>  export LANG=en_US.UTF-8
>  initdb -D data --locale=fr_FR.UTF-8
>  ...
>    provider:    icu
>    ICU locale:  en-US

What you're proposing with the 0003 patch still applies.

In the above case I think we would end up with:

provider=icu
ICU locale=fr-FR
lc_collate=fr_FR.UTF-8
lc_lctype=fr_FR.UTF-8

which is reasonable.


In the following cases we would initialize a libc cluster instead of an
ICU cluster:

- initdb --locale=C
- initdb --locale=POSIX
- LANG=C initdb
- LANG=C.UTF-8 initdb
- LANG=POSIX initdb
- ... possibly other locales that we find are unsuitable for ICU

That is, the rule "ICU by default" really means "ICU unless the locale
that we're being passed or getting from the environment
has semantics that ICU does not provide but we know libc provides,
in which case we fall back to libc".

The user who wants ICU imperatively should invoke
--icu-locale=something or --locale=something --locale-provider=icu
in which case we should not fallback to libc.
We still have to determine lc_collate and lc_ctype either from the
environment or from the locale argument (I think we should
favor the environment), except if the user specifies
--lc-collate=... lc-ctype=...


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.