Re: Do we want a hashset type?

On Mon, Jun 26, 2023 at 4:36 AM Joel Jacobson <joel@compiler.org> wrote:
>
> On Sun, Jun 25, 2023, at 11:42, Joel Jacobson wrote:
> >     SELECT hashset_contains('{}'::int4hashset, NULL::int);
> >
> > would be False, according to the General Rules.
> >
> ...
> > Applying the same rules, we'd have to return Unknown (which we represent as
> > null) for:
> >
> >     SELECT hashset_contains('{null}'::int4hashset, NULL::int);
> >
>
> Aha! I just discovered to my surprise that the corresponding array
> queries gives the same result:
>
> SELECT NULL = ANY(ARRAY[]::int[]);
>  ?column?
> ----------
>  f
> (1 row)
>
> SELECT NULL = ANY(ARRAY[NULL]::int[]);
>  ?column?
> ----------
>
> (1 row)
>
> I have no more objections; let's stick to the same null semantics as arrays and multisets.
>
> /Joel

Can you try to glue the attached to the hashset data type input function.
the attached will parse cstring with double quote and not. so '{1,2,3}' == '{"1","2","3"}'. obviously quote will preserve the inner string as is.