statistic over time ranges

statistics.sql

WITH
  timerange (ts) AS (SELECT generate_series(date_trunc('hour', min(collected_at)), date_trunc('hour', max(collected_at)) + '1 day'::interval, '1 hour'::interval) FROM statistic)
SELECT
    ts,
    count(stat),
    stddev(stat),
    avg(stat)
FROM
    timerange t
      LEFT JOIN statistic s ON s.collected_at <@ tsrange(t.ts, t.ts + '1 hour'::interval, '[)') 
GROUP BY 1
ORDER BY 1 ASC

;