Re: Document DateStyle effect on jsonpath string()

Peter Eisentraut <peter(at)eisentraut(dot)org> writes:
> What I'm concerned about is that this makes the behavior of JSON_QUERY
> non-immutable. Maybe there are other reasons for it to be
> non-immutable, in which case this isn't important. But it might be
> worth avoiding that?

Fair point, but haven't we already bit that bullet with respect
to timezones?

[ looks... ] Hmm, it looks like jsonb_path_exists_tz is marked
stable while jsonb_path_exists is claimed to be immutable.
So yeah, there's a problem here. I'm not 100% convinced that
jsonb_path_exists was truly immutable before, but for sure it
is not now, and that's bad.

regression=# select jsonb_path_query('"2023-08-15 12:34:56"', '$.timestamp().string()');
jsonb_path_query
-----------------------
"2023-08-15 12:34:56"
(1 row)

regression=# set datestyle = postgres;
SET
regression=# select jsonb_path_query('"2023-08-15 12:34:56"', '$.timestamp().string()');
jsonb_path_query
----------------------------
"Tue Aug 15 12:34:56 2023"
(1 row)

regards, tom lane