SELECT * FROM (VALUES (1)) AS t(id) CROSS JOIN unnest('{1,2}'::int[]) AS a(x) FULL JOIN unnest('{2,3}'::int[]) AS b(x) ON a.x = b.x WHERE t.id = 1
Execute this SQL, I get the result id | x | x ----+---+--- 1 | 1 | 1 | 2 | 2
My expection is id | x | x ----+---+--- 1 | 1 | 1 | 2 | 2 | | 3
The query plan is QUERY PLAN ------------------------------------------------------------------- Nested Loop Left Join (cost=0.01..0.08 rows=1 width=12) Join Filter: (a.x = b.x) -> Function Scan on unnest a (cost=0.00..0.03 rows=1 width=8) Filter: (1 = 1) -> Function Scan on unnest b (cost=0.00..0.02 rows=2 width=4)
So I think the FULL JOIN is replaced by LEFT JOIN.
The following SQL statements both give me the expected result. SELECT * FROM (VALUES (1)) AS t(id) CROSS JOIN unnest('{1,2}'::int[]) AS a(x) FULL JOIN unnest('{2,3}'::int[]) AS b(x) ON a.x = b.x;
SELECT * FROM (VALUES (1)) AS t(id), unnest('{1,2}'::int[]) AS a(x) FULL JOIN unnest('{2,3}'::int[]) AS b(x) ON a.x = b.x WHERE t.id = 1;
I can reproduce on PostgreSQL 16.0, 15.4 and 14.9.
