Message-ID: <12a7c9ddd5c44003869a114d0b5326fec27b2477.camel@j-davis.com>
Subject: Re: Collation version tracking for macOS
From: Jeff Davis <pgsql@j-davis.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Jeremy Schneider <schneider@ardentperf.com>, Peter Eisentraut
 <peter.eisentraut@enterprisedb.com>, Peter Geoghegan <pg@bowt.ie>, "Nasby,
 Jim" <nasbyj@amazon.com>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers
 <pgsql-hackers@postgresql.org>
Date: Tue, 29 Nov 2022 12:59:47 -0800
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On Wed, 2022-11-30 at 08:41 +1300, Thomas Munro wrote:
> In terms of user experience, I think that might mean that users of
> 'zh' who encounter warnings after a minor upgrade would therefore
> really only have the options of REFRESHing and rebuilding, or
> downgrading the package, because there's no way for us to access the
> older version.=C2=A0 Users of 'en' probably only encounter collversion
> changes when moving between OS releases with an ICU major version
> change, and then the various schemes in this thread can help them
> avoid the need to rebuild, until they eventually want to, if ever.

I installed the first minor release for each major, and got some new
tables. I think we can all agree that it's a lot easier to work with
information once it's in table form.

Here's what I found for the 'ar' locale (firstminor/lastminor are the
icu library versions, firstcollversion/lastcollversion are their
respective collation versions for the given locale):

 firstminor | lastminor | firstcollversion | lastcollversion=20
------------+-----------+------------------+-----------------
 60.1       | 60.3      | 153.80.32        | 153.80.32.1
 64.1       | 64.2      | 153.96.35        | 153.97.35.8
 68.1       | 68.2      | 153.14.38        | 153.14.38.8
(3 rows)

For 'en':

 firstminor | lastminor | firstcollversion | lastcollversion=20
------------+-----------+------------------+-----------------
 64.1       | 64.2      | 153.96           | 153.97
(1 row)

And for 'zh':

 firstminor | lastminor | firstcollversion | lastcollversion=20
------------+-----------+------------------+-----------------
 60.1       | 60.3      | 153.80.32        | 153.80.32.1
 64.1       | 64.2      | 153.96.35        | 153.97.35.8
 68.1       | 68.2      | 153.14.38        | 153.14.38.8
(3 rows)

It looks like collation versions do change in minor releases. It looks
like it's *not* safe to lock a collation to a major version *if* that
major version could be updated to a new minor. And we can't lock to a
minor, as I said earlier. Therefore, once we lock a collation down to a
major release, we better keep that in the icu_library_path, and never
touch it, and never install a new minor for that major.

Then again, maybe some of these are just about how the version is
reported... maybe 153.80.32 and 153.80.32.1 are really the same
version? But 64.1 -> 64.2 looks like a real difference.

I suppose the next step is to test with actual data and find
differences?


--=20
Jeff Davis
PostgreSQL Contributor Team - AWS