Re: Using FDW AddForeignUpdateTargets for a hidden pseudo-column

Bernd Helmle <mailings@oopsware.de> writes:
> --On 14. Juni 2016 10:32:13 +0000 Albe Laurenz <laurenz.albe@wien.gv.at>
> wrote:
>> I first thought of using the internal ROWID column that's probably
>> similar to your case, but that wouldn't fit into a tid's 6 bytes, and I
>> found that I could only add resjunk columns for existing columns of the
>> table.
>> Making the internal ROWID an explicit column in the foreign table seemed
>> just too ugly.

> The Informix FDW uses SelfItemPointerAttributeNumber. Luckily the Informix
> ROWID is a 4 byte encoded identifier (3 first significant bytes are the
> logical page number, last significant bytes is the slot number within that
> page). Maybe you can find a way of logically addressing your data, too? It
> only needs to fit within 6 bytes, afaik.

There's been some speculation about allowing FDWs to control the type of
the CTID column created for a foreign table, but it hasn't gotten past
the speculation stage yet.
        regards, tom lane