Amit-san, On Mon, Aug 3, 2020 at 2:55 PM Amit Langote <amitlangot...@gmail.com> wrote: > However, I noticed that having system columns like ctid, xmin, etc. in > the RETURNING list is now broken and maybe irrepairably due to the > approach we are taking in the patch. Let me show an example: > > drop table foo; > create table foo (a int, b int) partition by list (a); > create table foo1 (c int, b int, a int); > alter table foo1 drop c; > alter table foo attach partition foo1 for values in (1); > create table foo2 partition of foo for values in (2); > create table foo3 partition of foo for values in (3); > create or replace function trigfunc () returns trigger language > plpgsql as $$ begin new.b := 2; return new; end; $$; > create trigger trig before insert on foo2 for each row execute > function trigfunc(); > insert into foo values (1, 1), (2, 2), (3, 3); > update foo set a = 2 from (values (1), (2), (3)) s(x) where a = s.x > returning tableoid::regclass, ctid, xmin, xmax, *; > tableoid | ctid | xmin | xmax | a | b | x > ----------+----------------+------+------------+---+---+--- > foo2 | (4294967295,0) | 128 | 4294967295 | 2 | 2 | 1 > foo2 | (0,3) | 782 | 0 | 2 | 2 | 2 > foo2 | (0,4) | 782 | 0 | 2 | 2 | 3 > (3 rows) > > During foo1's update, it appears that we are losing the system > information in the physical tuple initialized during ExecInsert on > foo2 during its conversion back to foo1's reltype using the new code. > I haven't been able to figure out how to preserve the system > information in HeapTuple contained in the destination slot across the > conversion. Note we want to use the latter to project the RETURNING > list.
Thanks for pointing that out! > By the way, you'll need two adjustments to even get this example > working, one of which is a reported problem that system columns in > RETURNING list during an operation on partitioned table stopped > working in PG 12 [1] for which I've proposed a workaround (attached). > Another is that we forgot in our patch to "materialize" the virtual > tuple after conversion, which means slot_getsysattr() can't find it to > access system columns like xmin, etc. Ok, I’ll look at those closely. Best regards, Etsuro Fujita
