Re: PATCH: pg_dump to support "on conflict do update"

Laurenz Albe <laurenz.albe@cybertec.at> writes:
> On Sat, 2025-05-03 at 22:47 -0700, Tanin Na Nakorn wrote:
>> Here's the patch (against the latest master) that will make pg_dump support "on conflict do update" .
>>
>> There are 3 caveats:
>>
>> 1. The "on conflict do update" would apply to every table. In my opinion, this is fine.

> I don't think that is fine.  I think it would make the feature unusable for most cases.
> At the very least, there would have to be a way to specify which tables are affected.

Yeah.  I kind of feel that this entire idea is misguided.  pg_dump is
not an ETL tool, and bolting ETL-ish features onto it one at a time
seems destined to end in a mess.  But it's particularly awful that
the proposed switch design would apply to all tables.  That pretty
much makes it useless except in a dump that selects only one table.
It's also useless except in a --data-only dump, since if we create
the target table then we know perfectly well that it's empty to
start with.  So at this point you barely need pg_dump at all,
as opposed to some other tool that does a light syntactic
transformation on the result of COPY.

I think it could be interesting to try to build something that
*is* an ETL tool and is meant for cases like partial data loads.
But pg_dump is serving more than enough masters already.  Let's
not add this to its plate.

            regards, tom lane