Re: Add a test for "cannot truncate foreign table"

At Fri, 8 Jul 2022 01:06:18 +0900, Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote in
>
>
> On 2022/07/08 0:33, Tom Lane wrote:
> > Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> writes:
> >> On 2022/06/30 10:48, Yugo NAGATA wrote:
> >>> When a foreign table has handler but doesn't support TRUNCATE,
> >>> an error "cannot truncate foreign table xxx" occurs. So, what
> >>> about adding a test this message output? We can add this test
> >>> for file_fdw because it is one of the such foreign data wrappers.
> >
> >> Thanks for the patch! It looks good to me.
> >> I changed the status of this patch to ready-for-committer,
> >> and will commit it barring any objeciton.
> > This seems like a fairly pointless expenditure of test cycles
> > to me. Perhaps more importantly, what will you do when
> > somebody adds truncate support to that FDW?

As Fujii-san mentioned below, file_fdw has tests for INSERT/UPDATE and
DELETE. If somebody added DELETE to file_fdw, the test for DELETE
rejection would be turned into a normal test of the DELETE function.
I don't see a difference between TRUNCATE and other updating commands
from this point of view.

> One idea is to create dummy FDW (like foreign_data.sql regression test
> does) not supporting TRUNCATE and use it for the test.

I think the proposed test is not that for FDW framework, but for a
specific FDW module, file_fdw.

> BTW, file_fdw already has the similar test cases for INSERT, UPDATE
> and DELETE, as follows.
>
> -- updates aren't supported
> INSERT INTO agg_csv VALUES(1,2.0);
> ERROR: cannot insert into foreign table "agg_csv"
> UPDATE agg_csv SET a = 1;
> ERROR: cannot update foreign table "agg_csv"
> DELETE FROM agg_csv WHERE a = 100;
> ERROR: cannot delete from foreign table "agg_csv"

Agreed.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center