Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Mime-Version: 1.0 (1.0)
Subject: Re: Collation version tracking for macOS
From: Jeremy Schneider <schneider@ardentperf.com>
In-Reply-To: 
 <CA+hUKGKJFZR7Tw=9L7kxvv1wp-EN_wp__9a4xj=4HXciR-yw=Q@mail.gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>,
 Peter Geoghegan <pg@bowt.ie>,
 Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
 pgsql-hackers <pgsql-hackers@postgresql.org>
Date: Wed, 8 Jun 2022 16:40:37 -0700
Message-Id: <AB8B7BCF-4E06-48FA-B8AB-629AD1CC96FC@ardentperf.com>
References: 
 <CA+hUKGKJFZR7Tw=9L7kxvv1wp-EN_wp__9a4xj=4HXciR-yw=Q@mail.gmail.com>
To: Thomas Munro <thomas.munro@gmail.com>
Archived-At: 
 <https://www.postgresql.org/message-id/AB8B7BCF-4E06-48FA-B8AB-629AD1CC96FC%40ardentperf.com>
Precedence: bulk

New emoji are getting added with some frequency, it=E2=80=99s a thing lately=
=E2=80=A6

New Unicode chars use existing but unassigned code points. All code points a=
re able to be encoded, claimed or unclaimed.

Someone on old glibc or ICU can still store the new characters. As long as t=
here=E2=80=99s an input field. You wouldn=E2=80=99t believe some stuff I=E2=80=
=99ve seen people enter in the =E2=80=9Cname=E2=80=9D field for web apps=E2=80=
=A6 =F0=9F=99=84 It=E2=80=99ll get some undefined or default sort behavior f=
or unrecognized or unassigned code points.

When the libs are updated, those new chars begin to sort correctly, which is=
 a change and breaks indexes (and potentially other stuff).

-Jeremy

Sent from my TI-83

> On Jun 8, 2022, at 16:34, Thomas Munro <thomas.munro@gmail.com> wrote:
> =EF=BB=BFOn Thu, Jun 9, 2022 at 5:42 AM Tom Lane <tgl@sss.pgh.pa.us> wrote=
:
>> I'm sure that Apple are indeed updating the UTF8 data behind
>> their proprietary i18n APIs, but the libc APIs are mostly getting benign
>> neglect.
>=20
> As for how exactly they might be doing that, I don't know, but a bit
> of light googling tells me that a private, headerless,
> please-don't-call-me-directly copy of ICU arrived back in macOS
> 10.3[1].  I don't see it on my 12.4 system, but I also know that 12.x
> started hiding system libraries completely (the linker is magic and
> pulls libraries from some parallel dimension, there is no
> /usr/lib/libSystem.B.dylib file on disk, and yet otool -L
> <your_favourite_executable> references it).
>=20
> It's a lovely client machine, but I don't know if anyone really runs
> meaningful database server stuff on macOS.  I think if I did I'd be
> very keen to use ICU for everything directly, rather than trying to
> unpick any of that and talk to Apple's API...  I think the
> how-to-support-multiple-ICUs subrant/subthread is a much more
> interesting topic.  I have no idea if the dlopen() concept I mentioned
> is the right way forward, but FWIW the experimental patch I posted
> seems to work just fine on a Mac, using multiple ICU libraries
> installed by MacPorts, which might be useful to developers
> contemplating that stuff.
>=20
> [1] https://lists.apple.com/archives/xcode-users/2005/Jun/msg00633.html