Generate nested set structure from PostgreSQL ltree structure

ltree_to_nested.sql

CREATE VIEW anc_and_des AS 
SELECT 
        m.*,
        -- Count all descendats of a vertice
        ( SELECT COUNT(*) 
          FROM KeywordLtree AS d
          WHERE m.path @> d.path
        ) AS descendants,
        -- Count all ancestors of a vertice
        ( SELECT COUNT(*) 
          FROM KeywordLtree AS a
          WHERE a.path @> m.path
        ) AS ancestors,
        -- Enumerate vertices as with DFS flow
        ROW_NUMBER() OVER (ORDER BY m.path) AS rn
    FROM KeywordLtree AS m;
-- Generate output: 
-- left index for a vertice would be a 2 * number of a vertice in DFS - ancestros
-- right index for a vertice would be a left index + 2 * number of descendats - 1 (because without -1 we
-- would count current vertice twice
SELECT '#', id, value, 2 * rn - ancestors AS lft, 2 * rn - ancestors + 2 * descendants - 1 AS rgt
FROM anc_and_des
ORDER BY lft;

ltree_to_nested_2.sql

WITH aux AS (
  SELECT A.id, A.value, A.path, COUNT(*) as size, ROW_NUMBER(*) OVER(ORDER BY A.path) as ord
  FROM KeywordLtree A, KeywordLtree B
  WHERE A.path @> B.path
  GROUP BY A.id, A.value, A.path
)
SELECT '#', id, value, 1 + (ord - 1) * 2 - nlevel(path) as lft, (ord + size - 1) * 2 - nlevel(path) as rgt
FROM aux;