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

On Fri, 08 Jul 2022 09:44:10 +0900 (JST)
Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote:

> At Fri, 8 Jul 2022 01:06:18 +0900, Fujii Masao <masao.fujii@oss.nttdata.com> wrote in 
> > 
> > 
> > On 2022/07/08 0:33, Tom Lane wrote:
> > > Fujii Masao <masao.fujii@oss.nttdata.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.

Yes, the patch is an improvement for the test of flie_fdw. 

If we want to test foreign table modifications for the FDW framework, 
we will have to add such tests in foreign_data.sql, because foreign
table modifications are tested only for postgres_fdw and 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

Regards,
Yugo Nagata

-- 
Yugo NAGATA <nagata@sraoss.co.jp>