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

On Mon, Dec 04, 2023 at 03:35:48PM +0900, Sutou Kouhei wrote:
> I want to work on making COPY format extendable. I attach
> the first patch for it. I'll send more patches after this is
> merged.

Given the current discussion about adding JSON, I think this could be a
nice bit of refactoring that could ultimately open the door to providing
other COPY formats via shared libraries.

> In other words, this is just a refactoring for further
> changes to make COPY format extendable. If I use "complete
> the task and then request reviews for it" approach, it will
> be difficult to review because changes for it will be
> large. So I want to work on this step by step. Is it
> acceptable?

I think it makes sense to do this part independently, but we should be
careful to design this with the follow-up tasks in mind.

> So I measured COPY TO time with/without this change. You can
> see there is no significant loss of performance.
>
> Data: Random 32 bit integers:
>
> CREATE TABLE data (int32 integer);
> INSERT INTO data
> SELECT random() * 10000
> FROM generate_series(1, ${n_records});

Seems encouraging. I assume the performance concerns stem from the use of
function pointers. Or was there something else?

--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com