Re: [18] Policy on IMMUTABLE functions and Unicode updates

On Wed, 2024-07-24 at 08:20 -0400, Robert Haas wrote:
> I note in passing that the last time I saw a customer query with
> UPPER() in the join clause was... yesterday.

Can you expand on that? This thread is mostly about durable state so I
don't immediately see the connection.

> So I don't want to see us sit on our hands and assert that we don't
> need to worry about ctype because it's minor in comparison with
> collation. It *is* minor in comparison with collation. 

...

> But one problem
> can be small in comparison with another and still bad. If an aircraft
> is on fire whilst experiencing a dual engine failure, it's still in a
> lot of trouble even if the fire can be put out.

There's a qualitative difference between a collation update which can
break your PKs and FKs, and a ctype update which definitely will not.
Your analogy doesn't quite capture this distinction. I don't mean to
over-emphasize this point, but I do think we need to keep some
perspective here.

But I agree with your general point that we shouldn't dismiss the
problem just because it's minor. We should expect the problem to
surface at some point and be reasonably prepared.

Regards,
Jeff Davis