Re: Writable foreign tables: how to identify rows

Merlin Moncure <mmoncure@gmail.com> writes:
> On Wed, Mar 6, 2013 at 11:06 AM, Tom Lane <tgl@sss.pgh.pa.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