Example of rounding time to 5-second interval in ClickHouse.

rounding_time.txt

:) SELECT toDateTime(intDiv(toUInt32(EventTime), 5) * 5) AS k, count(), uniq(UserID) FROM hits_layer WHERE CounterID = 29761725 AND EventDate = today() AND EventTime >= now() - 600 GROUP BY k ORDER BY k

SELECT 
    toDateTime(intDiv(toUInt32(EventTime), 5) * 5) AS k, 
    count(), 
    uniq(UserID)
FROM hits_layer
WHERE (CounterID = 29761725) AND (EventDate = today()) AND (EventTime >= (now() - 600))
GROUP BY k
ORDER BY k ASC

┌───────────────────k─┬─count()─┬─uniq(UserID)─┐
│ 2016-06-20 23:49:55 │       1 │            1 │
│ 2016-06-20 23:50:00 │       1 │            1 │
│ 2016-06-20 23:50:05 │       1 │            1 │
│ 2016-06-20 23:50:10 │       1 │            1 │
│ 2016-06-20 23:50:25 │       3 │            1 │
│ 2016-06-20 23:50:45 │       1 │            1 │
│ 2016-06-20 23:50:50 │       1 │            1 │
│ 2016-06-20 23:51:00 │       1 │            1 │
│ 2016-06-20 23:51:05 │       2 │            1 │
│ 2016-06-20 23:51:25 │       1 │            1 │
│ 2016-06-20 23:51:30 │       1 │            1 │
│ 2016-06-20 23:51:40 │       1 │            1 │
│ 2016-06-20 23:51:55 │       1 │            1 │
│ 2016-06-20 23:52:05 │       2 │            2 │
│ 2016-06-20 23:52:15 │       1 │            1 │
│ 2016-06-20 23:52:30 │       1 │            1 │
│ 2016-06-20 23:53:20 │       1 │            1 │
│ 2016-06-20 23:53:35 │       1 │            1 │
│ 2016-06-20 23:54:05 │       1 │            1 │
│ 2016-06-20 23:54:20 │       1 │            1 │
│ 2016-06-20 23:56:00 │       1 │            1 │
│ 2016-06-20 23:56:05 │       3 │            1 │
│ 2016-06-20 23:56:45 │       2 │            2 │
│ 2016-06-20 23:57:00 │       1 │            1 │
│ 2016-06-20 23:57:15 │       1 │            1 │
│ 2016-06-20 23:57:20 │       1 │            1 │
│ 2016-06-20 23:57:25 │       1 │            1 │
└─────────────────────┴─────────┴──────────────┘

27 rows in set. Elapsed: 0.053 sec. Processed 352.26 thousand rows, 6.34 MB (6.70 million rows/s., 120.55 MB/s.)