Florents Tselai <florents.tse...@gmail.com> writes: > On 22 May 2025, at 11:56 PM, Peter Eisentraut <pe...@eisentraut.org> wrote: >> I don't understand how this discussion got to the conclusion that functions >> that depend on the locale cannot be immutable. Note that the top-level >> functions lower, upper, and initcap themselves are immutable.
> I assume you mean that they’re set at initdb time, so there’s no mutability > concern? Yeah, I think Peter's right and I'm wrong. Obviously this ties into our philosophical debate about how immutable is immutable. But as long as the functions only depend on locale settings that are fixed at database creation, I think it's okay to consider them immutable. If you were, say, depending on LC_NUMERIC, it would clearly be unsafe to consider that immutable, so I'm not quite sure if this is the end of the discussion. But for what's mentioned in the thread title, I think we only care about LC_CTYPE. regards, tom lane