Here is an example using postgres_fdw.
[Terminal 1]
postgres=# create table t (a int, b int);
CREATE TABLE
postgres=# insert into t values (1, 1);
INSERT 0 1
postgres=# begin;
BEGIN
postgres=# update t set b = b * 2;
UPDATE 1
[Terminal 2]
postgres=# create foreign table ft (a int) server loopback options
(table_name 'lbt');
CREATE FOREIGN TABLE
postgres=# insert into ft values (1);
INSERT 0 1
postgres=# select tableoid, ctid, * from ft;
tableoid | ctid | a
----------+-------+---
25092 | (0,1) | 1
(1 row)
postgres=# select ft.tableoid, ft.ctid, ft.* from t, ft where t.a = ft.a
for update;
[Terminal 1]
postgres=# commit;
COMMIT
[Terminal 2]
postgres=# select ft.tableoid, ft.ctid, ft.* from t, ft where t.a = ft.a
for update;
tableoid | ctid | a
----------+----------------+---
0 | (4294967295,0) | 1
(1 row)
Note that tableoid and ctid have been changed!
I think the reason for that is because EvalPlanQualFetchRowMarks doesn't
properly set tableoid and ctid for foreign tables, IIUC. I think this
should be fixed. Please find attached a patch. The patch slightly
relates to [1], so if it is reasonable, I'll update [1] on top of this.
[1] https://commitfest.postgresql.org/action/patch_view?id=1386
Best regards,
Etsuro Fujita
