From: Tom Lane <tgl@sss.pgh.pa.us>
To: Florents Tselai <florents.tselai@gmail.com>
cc: Peter Eisentraut <peter@eisentraut.org>,
        Robert Haas <robertmhaas@gmail.com>,
        Alexander Korotkov <aekorotkov@gmail.com>,
        pgsql-hackers <pgsql-hackers@lists.postgresql.org>,
        Andrew Dunstan <andrew@dunslane.net>
Subject: Re: PATCH: jsonpath string methods: lower, upper, initcap, l/r/btrim,
 replace, split_part
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Comments: In-reply-to Florents Tselai <florents.tselai@gmail.com>
	message dated "Fri, 23 May 2025 20:06:25 +0300"
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Date: Fri, 23 May 2025 13:52:01 -0400
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Florents Tselai <florents.tselai@gmail.com> writes:
> On 22 May 2025, at 11:56=E2=80=AFPM, Peter Eisentraut <peter@eisentraut.=
org> wrote:
>> I don't understand how this discussion got to the conclusion that funct=
ions that depend on the locale cannot be immutable.  Note that the top-lev=
el functions lower, upper, and initcap themselves are immutable.

> I assume you mean that they=E2=80=99re set at initdb time, so there=E2=80=
=99s 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