Re: Writable foreign tables: how to identify rows

Merlin Moncure <mmoncure(at)gmail(dot)com> writes:
> On Wed, Mar 6, 2013 at 11:06 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Yeah, I considered that. I thought seriously about proposing that we
>> forget magic row identifiers altogether, and instead make postgres_fdw
>> require a remote primary key for a foreign table to be updatable.

> IMO, Utilizing anything but this for remote record identification is
> an implementation specific optimization. Aren't the semantics
> different though? If you go:

> update foo set id = 1 where id = 1;

> the primary key would not change, but the ctid would. or is that
> already a handled?

In postgres_fdw as it currently stands, the remote ctid would change.
I'm not sure we should posit that as a universal property of FDWs
though. It's not even a meaningful question for FDWs with no underlying
rowid concept.

regards, tom lane