Horton

Re: Built-in CTYPE provider

Daniel Verite <daniel@manitou-mail.org>

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From: "Daniel Verite" <daniel@manitou-mail.org>
To: "Peter Eisentraut" <peter@eisentraut.org>
Cc: Jeff Davis <pgsql@j-davis.com>, Robert Haas <robertmhaas@gmail.com>, Jeremy Schneider <schneider@ardentperf.com>, pgsql-hackers@postgresql.org
Date: 2024-01-18T19:42:10Z
Lists: pgsql-hackers 
	Peter Eisentraut wrote:

> > If the Postgres default was bytewise sorting+locale-agnostic
> > ctype functions directly derived from Unicode data files,
> > as opposed to libc/$LANG at initdb time, the main
> > annoyance would be that "ORDER BY textcol" would no
> > longer be the human-favored sort.
> 
> I think that would be a terrible direction to take, because it would 
> regress the default sort order from "correct" to "useless".  Aside from 
> the overall message this sends about how PostgreSQL cares about
> locales and Unicode and such.

Well, offering a viable solution to avoid as much as possible
the dreaded:

"WARNING: collation "xyz" has version mismatch
... HINT: Rebuild all objects affected by this collation..."

that doesn't sound like a bad message to send. 

Currently, to have in codepoint order the indexes that don't need a
linguistic order, you're supposed to use collate "C", which then means
that upper(), lower() etc.. don't work beyond ASCII.
Here our Unicode support is not good enough, and the proposal
addresses that.


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

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.