[HACKERS] postgres_fdw : Not able to update foreign table referring to a local table's view when use_remote_estimate = true

[Rajkumar Raghuwanshi]

Hi,

I observed below in postgres_fdw.

*Observation:* Update a foreign table which is referring to a local table's
view (with use_remote_estimate = true) getting failed with below error.
                    ERROR:  column "ctid" does not exist
                    CONTEXT:  Remote SQL command: EXPLAIN SELECT c1, ctid
FROM public.lt_view FOR UPDATE

create extension postgres_fdw;
create server link_server foreign data wrapper postgres_fdw options (host
'localhost',dbname 'postgres', port '5447');
create user mapping for public server link_server;

create table lt (c1 integer, c2 integer);
insert into lt values (1,null);
create view lt_view as select * from lt;
create foreign table ft (c1 integer,c2 integer) server link_server options
(table_name 'lt_view');

--alter server with use_remote_estimate 'false'
alter server link_server options (add use_remote_estimate 'false');
--update foreign table refering to local view -- able to update
update ft set c2 = c1;
UPDATE 1

--alter server with use_remote_estimate 'true'
alter server link_server options (SET use_remote_estimate 'true');
--update foreign table refering to local view -- fail, throwing error
update ft set c2 = c1;
psql:/home/edb/Desktop/edb_work/Postgres_Fdw/dml_pushdown_35882/observation_view.sql:24:
ERROR:  column "ctid" does not exist
CONTEXT:  Remote SQL command: EXPLAIN SELECT c1, ctid FROM public.lt_view
FOR UPDATE

Thanks & Regards,
Rajkumar Raghuwanshi
QMG, EnterpriseDB Corporation

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