Re: BUG #15552: Unexpected error in COPY to a foreign table in a transaction

(2018/12/19 11:52), Amit Langote wrote:
> On 2018/12/19 11:38, Michael Paquier wrote:
>> I would rather not play with the semantics of heap_sync() on
>> the back branches as well as on a thread dealing with a bug about COPY
>> with foreign tables. Such discussions deserve a larger audience on
>> -hackers.
>
> +1

OK, I agree with that too.

> Patch looks good, by the way.

Thanks for working on this, Michael!

>> it is a bit funny to see COPY FREEZE working for foreign tables
>> actually, but perhaps this has some use-cases for some FDWs, so I'd
>> rather not touch it.
>
> Hmm, note that we don't pass CopyState->freeze option to the FDW drivers
> today, though we may in the future when we add an *actual* COPY interface
> to FDWs. Wouldn't it be a good idea to prevent specifying the FREEZE
> option for foreign tables as COPY targets until then?

Not sure. In general, I think it would be a good thing that the FDW is
able to see options specified in the COPY command, though.

> Of course, that's
> something for -hackers to consider.

Agreed.

BTW I noticed that this error occurs not only for foreign tables but for
views with INSTEAD OF INSERT triggers. Here is an example on HEAD:

postgres=# create table instead_of_insert_tbl(id serial, name text);
CREATE TABLE
postgres=# begin;
BEGIN
postgres=# create view instead_of_insert_tbl_view as select ''::text as str;
CREATE VIEW
postgres=# create function fun_instead_of_insert_tbl() returns trigger
as $$ beg
in insert into instead_of_insert_tbl (name) values (new.str); return
null; end;
$$ language plpgsql;
CREATE FUNCTION
postgres=# create trigger trig_instead_of_insert_tbl_view instead of
insert on i
nstead_of_insert_tbl_view for each row execute procedure
fun_instead_of_insert_t
bl();
CREATE TRIGGER
postgres=# copy instead_of_insert_tbl_view from stdin;
Enter data to be copied followed by a newline.
End with a backslash and a period on a line by itself, or an EOF signal.
>> test1
>> \.
ERROR: could not open file "base/13788/16426": そのようなファイルやディ
レクトリはありません

("そのようなファイルやディレクトリはありません" means no such file or
directory.)

To fix this I think we would also need the same treatment for the view case.

Best regards,
Etsuro Fujita