Quick search the most similar objects in the n-dimensional space
PostgreSQL using cube

Using PostgreSQL this becomes pretty easy with the cube extension which I explained on your other question.. Sample data.

CREATE TABLE foo AS
SELECT *
FROM ( VALUES
  (1, cube(ARRAY[5 , 19, 42, 12, 16]) ),
  (2, cube(ARRAY[3 , 23, 38, 15, 12]) ),
  (3, cube(ARRAY[14, 21, 32, 33, 1 ]) ),
  (4, cube(ARRAY[12, 29, 21, 24, 5 ]) )
) AS t(id, c);


Finding distance...

SELECT
  id,
  c,
  c2,
  cube_distance(c,c2),
  rank() OVER (ORDER BY cube_distance(c,c2))
FROM foo
CROSS JOIN ( SELECT cube(ARRAY[4,20,40,14,15]) )
  AS t(c2)
ORDER BY cube_distance(c, c2);


Outputs.

 id |          c          |         c2          |  cube_distance   | rank 
----+---------------------+---------------------+------------------+------
  1 | (5, 19, 42, 12, 16) | (4, 20, 40, 14, 15) |  3.3166247903554 |    1
  2 | (3, 23, 38, 15, 12) | (4, 20, 40, 14, 15) | 4.89897948556636 |    2
  4 | (12, 29, 21, 24, 5) | (4, 20, 40, 14, 15) | 26.5706605111728 |    3
  3 | (14, 21, 32, 33, 1) | (4, 20, 40, 14, 15) | 26.8700576850888 |    4