SELECT v,  rolling_median(v::double precision, 5) over() FROM generate_series(1, 10) as t(v);
 v  | rolling_median 
----+----------------
  1 |               
  2 |               
  3 |               
  4 |               
  5 |              3
  6 |              4
  7 |              5
  8 |              6
  9 |              7
 10 |              8
(10 rows)

SELECT v,  rolling_median(v, 3) over() FROM (VALUES (1), (1.1), (0.9), (1.1), (0.95), (2.1), (1.95), (2.0), (2.05), (3.11), (2.99), (3.05), (3.0)) as t(v);
  v   | rolling_median 
------+----------------
    1 |               
  1.1 |               
  0.9 |              1
  1.1 |            1.1
 0.95 |           0.95
  2.1 |            1.1
 1.95 |           1.95
  2.0 |              2
 2.05 |              2
 3.11 |           2.05
 2.99 |           2.99
 3.05 |           3.05
  3.0 |              3
(13 rows)

SELECT v,  rolling_median(v, 3) over() FROM (VALUES (1), (1.1)) as t(v);
  v  | rolling_median 
-----+----------------
   1 |               
 1.1 |               
(2 rows)

SELECT v,  rolling_median(v::double precision, 3) over() FROM (VALUES (NULL), (NULL), (NULL)) as t(v);
 v | rolling_median 
---+----------------
   |               
   |               
   |               
(3 rows)

SELECT v,  rolling_median(v, 3) over() FROM (VALUES (1), (1.1), (0.9), (1.1), (NULL), (NULL), (1.95)) as t(v);
  v   | rolling_median 
------+----------------
    1 |               
  1.1 |               
  0.9 |              1
  1.1 |            1.1
      |               
      |               
 1.95 |               
(7 rows)