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

Hi,

In <CAEG8a3LxnBwNRPRwvmimDvOkPvYL8pB1+rhLBnxjeddFt3MeNw@mail.gmail.com>
  "Re: Make COPY format extendable: Extract COPY TO format implementations" on Fri, 2 Feb 2024 15:27:15 +0800,
  Junwang Zhao <zhjwpku@gmail.com> wrote:

> I agree CopyToRoutine should be placed into CopyToStateData, but
> why set it after ProcessCopyOptions, the implementation of
> CopyToGetRoutine doesn't make sense if we want to support custom
> format in the future.
> 
> Seems the refactor of v11 only considered performance but not
> *extendable copy format*.

Right.
We focus on performance for now. And then we will focus on
extendability. [1]

[1]
https://www.postgresql.org/message-id/flat/20240130.171511.2014195814665030502.kou%40clear-code.com#757a48c273f140081656ec8eb69f502b

> If V7 and V10 have no performance reduction, then I think V6 is also
> good with performance, since most of the time goes to CopyToOneRow
> and CopyFromOneRow.

Don't worry. I'll re-submit changes in the v6 patch set
again after the current patch set that focuses on
performance is merged.

> I just think we should take the *extendable* into consideration at
> the beginning.

Introducing Copy{To,From}Routine is also valuable for
extendability. We can improve extendability later. Let's
focus on only performance for now to introduce
Copy{To,From}Routine.


Thanks,
-- 
kou