create table parent (
 id SERIAL NOT NULL,
 owner_id INTEGER NOT NULL
);
create table child (
 parent_id INTEGER NOT NULL,
 owner_id INTEGER NOT NULL
);
create table child_nopart (
 parent_id INTEGER NOT NULL,
 owner_id INTEGER NOT NULL
);
insert into parent (owner_id) values (1), (2), (3), (3);
insert into child (parent_id, owner_id) values (1, 1), (2, 2), (3, 3), (5, 3);
insert into child_nopart (parent_id, owner_id) values (1, 1), (2, 2), (3, 3), (5, 3);
select create_hash_partitions('child', 'owner_id', 2);

select *
 from parent
 left join child on child.parent_id = parent.id and child.owner_id = parent.owner_id
 where parent.owner_id = 3 and parent.id in (3, 4);

id	owner_id	parent_id	owner_id
3	3		3		3
3	3		5		3
4	3		3		3
4	3		5		3

select *
 from parent
 left join child on child.parent_id = parent.id and child.owner_id = 3
 where parent.owner_id = 3 and parent.id in (3, 4);
select *
 from parent
 left join child_1 child on child.parent_id = parent.id and child.owner_id = parent.owner_id
 where parent.owner_id = 3 and parent.id in (3, 4);
select *
 from parent
 left join child_nopart child on child.parent_id = parent.id and child.owner_id = parent.owner_id
 where parent.owner_id = 3 and parent.id in (3, 4);
select *
 from parent
 left join child on child.parent_id = parent.id and child.owner_id = parent.owner_id
 where parent.owner_id = 3;

id	owner_id	parent_id	owner_id
3	3		3		3
4	3		<null>		<null>