Multi-insert into a partitioned table with before insert row trigger causes server crash on latest HEAD

Hi All,

The copy command on partitioned table causes server crash when before
insert row trigger is created on one of its partition. Please find the
following test-case to reproduce the crash.

-- create a partitioned table
create table part_copy_test (a int, b int, c text) partition by list (b);
create table part_copy_test_a1 partition of part_copy_test for values in(1);
create table part_copy_test_a2 partition of part_copy_test for values in(2);

-- insert enough rows to allow multi-insert into a partitioned table.
copy (select x,1,'One' from generate_series(1,1000) x
union all
select x,2,'two' from generate_series(1001,1010) x
union all
select x,1,'One' from generate_series(1011,1020) x) to
'/tmp/multi_insert_data.csv';

-- create before insert row trigger on part_copy_test_a2
create function part_ins_func() returns trigger language plpgsql as
$$
begin
return new;
end;
$$;

create trigger part_ins_trig before insert on part_copy_test_a2
for each row execute procedure part_ins_func();

-- run copy command on partitioned table.
copy part_copy_test from '/tmp/multi_insert_data.csv';

postgres=# copy part_copy_test from '/tmp/multi_insert_data.csv';
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!>

I've spent some time looking into this issue and found that,
CopyFrom() is trying perform multi-insert for the partition that has
before insert row trigger created on it which is not expected. When a
normal table with before insert row trigger is created, CopyFrom
doesn't allow multi insert on such tables and i guess same should be
the case with table partition as well. Please correct me if i my
understanding is wrong ?

Thanks,

--
With Regards,
Ashutosh Sharma
EnterpriseDB:http://www.enterprisedb.com