Re: Make COPY format extendable: Extract COPY TO format implementations - Mailing list pgsql-hackers

On Fri, Jan 26, 2024 at 4:32 PM Sutou Kouhei <kou@clear-code.com> wrote:
>
> Hi,
>
> In <CAEG8a3+-oG63GeG6v0L8EWi_8Fhuj9vJBhOteLxuBZwtun3GVA@mail.gmail.com>
>   "Re: Make COPY format extendable: Extract COPY TO format implementations" on Fri, 26 Jan 2024 16:18:14 +0800,
>   Junwang Zhao <zhjwpku@gmail.com> wrote:
>
> > In the current implementation, there is no way that one can check
> > incompatibility
> > options in ProcessCopyOptions, we can postpone the check in CopyFromStart
> > or CopyToStart, but I think it is a little bit late. Do you think
> > adding an extra
> > check for incompatible options hook is acceptable (PFA)?
>
> Thanks for the suggestion! But I think that a custom handler
> can do it in
> CopyToProcessOption()/CopyFromProcessOption(). What do you
> think about this? Or could you share a sample COPY TO/FROM
> WITH() SQL you think?

CopyToProcessOption()/CopyFromProcessOption() can only handle
single option, and store the options in the opaque field,  but it can not
check the relation of two options, for example, considering json format,
the `header` option can not be handled by these two functions.

I want to find a way when the user specifies the header option, customer
handler can error out.

>
>
> Thanks,
> --
> kou



--
Regards
Junwang Zhao