Re: Collation version tracking for macOS

On Tue, 2022-11-29 at 11:27 -0500, Joe Conway wrote:
> My vote is for something like #5. The collversion should indicate a
> specific immutable ordering behavior.

Easier said than done:

https://www.postgresql.org/message-id/abddc35a7a447d93e2b8371a1a9052cb48866070.camel@j-davis.com

Even pointing at a specific minor version doesn't guarantee that
specific ICU code is loaded. It could also be a mix of different minor
versions that happen to be installed.

But if we ignore that problem for a moment, and assume that major
version is precise enough, let me make another proposal (not advocating
for this, but wanted to put it out there):

6. Create a new concept of a "locked down collation" that points at
some specific collation code (identified by some combination of library
version and collation version or whatever else can be used to identify
it). If a collation is locked down, it would never have a fallback or
any other magic, it would either find the code it's looking for, or
fail. If a collation is not locked down, it would look only in the
built-in ICU library, and warn if it detects some kind of change
(again, by whatever heuristic we think is reasonable).

#6 doesn't answer all of the problems I pointed out earlier:

https://www.postgresql.org/message-id/83faecb4a89dfb5794938e7b4d9f89daf4c5d631.camel@j-davis.com

but could be a better starting place for answers.

--
Jeff Davis
PostgreSQL Contributor Team - AWS