Re: general purpose array_sort - Mailing list pgsql-hackers

Hi Jian,

On Fri, Oct 11, 2024 at 1:12 PM jian he <jian.universality@gmail.com> wrote:
>
> tricky case:
> should we allow array element type to be composite/domain?
> currently seems to work fine.
>
>
> create table t(b int[]);
> insert into t values ('{{1,3}}'), ('{{1,2}}');
>
>  select array_sort((select array_agg(t) from t), 'desc');
>             array_sort
> -----------------------------------
>  {"(\"{{1,3}}\")","(\"{{1,2}}\")"}
>
>
> select array_sort((t.b)) from t;
> ERROR:  multidimensional arrays sorting are not supported
>
>
> select array_sort((select array_agg(t.b) from t));
> ERROR:  multidimensional arrays sorting are not supported

I tried the above cases, and the first one works because it's
a one dim array of composite type, the other two fails because
they are multidimensional.

It seems there is not much meaning to sort composite type,
so are you proposing we should error on that?

--
Regards
Junwang Zhao