Pavel Stehule writes:
postgres=# explain SELECT name
FROM person
WHERE name IN (
SELECT name FROM person p
LEFT JOIN person_data ON p.id = person_data.id);
ERROR: failed to build any 2-way joins
postgres=# explain SELECT name
FROM person
WHERE name IN (
SELECT name FROM person p
LEFT JOIN person_data ON p.id = person_data.id);
ERROR: failed to build any 2-way joins
regards, tom lane