Re: Rework of collation code, extensibility

Jeff Davis <pgsql@j-davis.com>

From: Jeff Davis <pgsql@j-davis.com>

To: pgsql-hackers@postgresql.org

Date: 2022-12-22T05:40:57Z

Lists: pgsql-hackers

Attachments

v5-0007-Add-test-module-for-libc-collation-provider-hook.patch (text/x-patch) patch v5-0007
v5-0006-Support-multiple-libc-collation-provider-librarie.patch (text/x-patch) patch v5-0006
v5-0005-Add-test-module-for-icu-collation-provider-hook.patch (text/x-patch) patch v5-0005
v5-0004-Support-multiple-ICU-collation-provider-libraries.patch (text/x-patch) patch v5-0004
v5-0003-Refactor-pg_locale_t-routines.patch (text/x-patch) patch v5-0003
v5-0002-Add-pg_strxfrm-and-pg_strxfrm_prefix.patch (text/x-patch) patch v5-0002
v5-0001-Add-pg_strcoll-and-pg_strncoll.patch (text/x-patch) patch v5-0001

On Sat, 2022-12-17 at 19:14 -0800, Jeff Davis wrote:
> Attached is a new patch series. I think there are enough changes that
> this has become more of a "rework" of the collation code rather than
> just a refactoring. This is a continuation of some prior work[1][2]
> in
> a new thread given its new scope.

Here's version 5. There are a number of fixes, and better tests, and
it's passing in CI.

The libc hook support is still experimental, but what's working is
passing in CI, even on windows. The challenges with libc hook support
are:

 * It obviously doesn't replace all of libc, so the separation is not
as clean and there are a number of callers throughout the code that
don't necessarily care about specific collations. 

 * libc relies on setlocale() / uselocale(), which is global state and
not as easy to track.

 * More platform issues (obviously) and harder to test.

-- 
Jeff Davis
PostgreSQL Contributor Team - AWS

Commits

Remove unnecessary #ifdef USE_ICU and branch.
- e0b3074e8944 16.0 landed
Refactor to introduce pg_locale_deterministic().
- 6974a8f7682b 16.0 landed
Refactor to add pg_strcoll(), pg_strxfrm(), and variants.
- d87d548cd030 16.0 landed
Fix MSVC build
- c971a5b27ac9 16.0 cited