Re: Make COPY format extendable: Extract COPY TO format implementations

On Fri, May 2, 2025 at 9:56 PM Sutou Kouhei <kou(at)clear-code(dot)com> wrote:
>
> Hi,
>
> In <CAD21AoBGRFStdVbHUcxL0QB8wn92J3Sn-6x=RhsSMuhepRH0NQ(at)mail(dot)gmail(dot)com>
> "Re: Make COPY format extendable: Extract COPY TO format implementations" on Fri, 2 May 2025 21:38:32 -0700,
> Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> >> How about requiring schema for all custom formats?
> >>
> >> Valid:
> >>
> >> COPY ... TO ... (FORMAT 'text');
> >> COPY ... TO ... (FORMAT 'my_schema.jsonlines');
> >>
> >> Invalid:
> >>
> >> COPY ... TO ... (FORMAT 'jsonlines'); -- no schema
> >> COPY ... TO ... (FORMAT 'pg_catalog.text'); -- needless schema
> >>
> >> If we require "schema" for all custom formats, we don't need
> >> to depend on search_path.
> >
> > I'm concerned that users cannot use the same format name in the FORMAT
> > option depending on which schema the handler function is created.
>
> I'm not sure that it's a problem or not. If users want to
> use the same format name, they can install the handler
> function to the same schema.
>
> >> Why do we need to assign a unique ID? For performance? For
> >> RegisterCustomCopyFormatOption()?
> >
> > I think it's required for monitoring purposes for example. For
> > instance, we can set the format ID in the progress information and the
> > progress view can fetch the format name by the ID so that users can
> > see what format is being used in the COPY command.
>
> How about setting the format name instead of the format ID
> in the progress information?

The progress view can know only numbers. We need to extend the
progress view infrastructure so that we can pass other data types.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com