Thank you for the clarification.
пн, 16 авг. 2021 г. в 19:22, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>
> PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> > Why concat_ws and concat is not immutable?
>
> Those invoke datatype-specific output functions, which aren't guaranteed
> to be immutable. Maybe ideally they would be, but we have too much
> historical baggage --- for example, timestamp_out has always depended
> on DateStyle.
>
> regards, tom lane