PostgreSQL use value from previous row if missing

Question

I have a following query:

WITH t as (
  SELECT date_trunc(\'hour\', time_series) as trunc 
  FROM generate_series(\'2013-02-27 22:00\'::timestamp, \'2013-02-         


        

Answer 1

Try:

WITH t as (
  SELECT time_series as trunc 
    FROM generate_series('2013-02-27 22:00'::timestamp, '2013-02-28 2:00', 
                         '1 hour') as time_series
)
SELECT DISTINCT ON(t.trunc) t.trunc, e.id
  FROM t
  JOIN event e
    ON e.created < t.trunc 
 ORDER BY t.trunc, e.created DESC

If it is too slow - tell me. I will give you a faster query.