Horton

Re: Built-in CTYPE provider

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: Jeff Davis <pgsql@j-davis.com>, Daniel Verite <daniel@manitou-mail.org>
Cc: Robert Haas <robertmhaas@gmail.com>, Jeremy Schneider <schneider@ardentperf.com>, pgsql-hackers@postgresql.org
Date: 2024-03-25T07:29:47Z
Lists: pgsql-hackers 
On 22.03.24 18:26, Jeff Davis wrote:
> On Fri, 2024-03-22 at 15:51 +0100, Peter Eisentraut wrote:
>> I think this might be too big of a compatibility break.  So far,
>> initcap('123abc') has always returned '123abc'.  If the new collation
>> returns '123Abc' now, then that's quite a change.  These are not some
>> obscure Unicode special case characters, after all.
> 
> It's a new collation, so I'm not sure it's a compatibility break. But
> you are right that it is against documentation and expectations for
> INITCAP().
> 
>> What is the ICU configuration incantation for this?  Maybe we could
>> have
>> the builtin provider understand some of that, too.
> 
> https://unicode-org.github.io/icu-docs/apidoc/dev/icu4c/stringoptions_8h.html#a4975f537b9960f0330b233061ef0608d
> https://unicode-org.github.io/icu-docs/apidoc/dev/icu4c/stringoptions_8h.html#afc65fa226cac9b8eeef0e877b8a7744e
> 
>> Or we should create a function separate from initcap.
> 
> If we create a new function, that also gives us the opportunity to
> accept optional arguments to control the behavior rather than relying
> on collation for every decision.

Right.  I thought when you said there is an ICU configuration for it, 
that it might be like collation options that you specify in the locale 
string.  But it appears it is only an internal API setting.  So that, in 
my mind, reinforces the opinion that we should leave initcap() as is and 
make a new function that exposes the new functionality.  (This does not 
have to be part of this patch set.)

Commits

  1. Support PG_UNICODE_FAST locale in the builtin collation provider.

  2. Support Unicode full case mapping and conversion.

  3. Fix test failures when language environment is not UTF-8.

  4. Add unicode_strtitle() for Unicode Default Case Conversion.

  5. Use version for builtin collations.

  6. Fix convert_case(), introduced in 5c40364dd6.

  7. Inline basic UTF-8 functions.

  8. Support C.UTF-8 locale in the new builtin collation provider.

  9. Fix another warning, introduced by 846311051e.

  10. Address more review comments on commit 2d819a08a1.

  11. Fix unreachable code warning from commit 2d819a08a1.

  12. Introduce "builtin" collation provider.

  13. Catalog changes preparing for builtin collation provider.

  14. Unicode case mapping tables and functions.

  15. Add Unicode property tables.

  16. Documentation update for Standard Collations.

  17. Cleanup for unicode-update build target and test.

  18. Shrink Unicode category table.

  19. Make some error strings more generic

  20. pg_upgrade: copy locale and encoding information to new cluster.

  21. Update Unicode data to Unicode 15.0.0

  22. Create a new type category for "internal use" types.