Optimization: Recursive CTE Boundaries

Choose the safer and more performant recursive query. Query A: WITH RECURSIVE tree AS (SELECT id, parent_id, 1 AS lvl FROM nodes WHERE parent_id IS NULL UNION ALL SELECT n.id, n.parent_id, t.lvl + 1 FROM nodes n JOIN tree t ON n.parent_id = t.id) SELECT * FROM tree; Query B: WITH RECURSIVE tree AS (SELECT id, parent_id, 1 AS lvl FROM nodes WHERE parent_id IS NULL UNION ALL SELECT n.id, n.parent_id, t.lvl + 1 FROM nodes n JOIN tree t ON n.parent_id = t.id WHERE t.lvl < 20) SELECT * FROM tree;