Hmmm. Yes the unicode rules seem to be a little strict on conforming to the past! I just made the following fix to my python code in forming the upper case alphabet from the lower case one:
"Peter J. Holzer" <hjp-pgsql@hjp.at> writes: > On 2023-03-13 17:38:51 -0400, Celia McInnis wrote: >> I would be really happy if postgresql had an upper case version of the ß >> german character.
> But the 'ß' is a bit special as it is usually uppercased to 'SS' > (although 'ẞ' is now officially allowed, too). > Apparently your (and my) locale doesn't uppercase ß at all, which isn't > correct according to German spelling rules but was very common in the > last decades.
Our code for libc locales doesn't support upcasing 'ß' to 'SS', because it uses towlower() which can only manage one-character-to-one-character transformations. It should work for upcasing to 'ẞ', but as you say, you need to find a locale that thinks that should happen.
You might have better luck if you have a version of Postgres that supports ICU and you can use an ICU locale. That code path doesn't appear to have any hard-wired assumption about how many characters in convert to how many out.
