Grouping into interval of 5 minutes within a time range

Solution 1:

This works with every interval.

PostgreSQL

SELECT
    TIMESTAMP WITH TIME ZONE 'epoch' +
    INTERVAL '1 second' * round(extract('epoch' from timestamp) / 300) * 300 as timestamp,
    name,
    count(b.name)
FROM time a, id 
WHERE …
GROUP BY 
round(extract('epoch' from timestamp) / 300), name

MySQL

SELECT
    timestamp,  -- not sure about that
    name,
    count(b.name)
FROM time a, id 
WHERE …
GROUP BY 
UNIX_TIMESTAMP(timestamp) DIV 300, name

Solution 2:

I came across the same issue.

I found that it is easy to group by any minute interval is just dividing epoch by minutes in amount of seconds and then either rounding or using floor to get ride of the remainder. So if you want to get interval in 5 minutes you would use 300 seconds.

    SELECT COUNT(*) cnt, 
    to_timestamp(floor((extract('epoch' from timestamp_column) / 300 )) * 300) 
    AT TIME ZONE 'UTC' as interval_alias
    FROM TABLE_NAME GROUP BY interval_alias

interval_alias       cnt
-------------------  ----  
2010-11-16 10:30:00  2
2010-11-16 10:35:00  10
2010-11-16 10:45:00  8
2010-11-16 10:55:00  11 

This will return the data correctly group by the selected minutes interval; however, it will not return the intervals that don't contains any data. In order to get those empty intervals we can use the function generate_series.

    SELECT generate_series(MIN(date_trunc('hour',timestamp_column)),
    max(date_trunc('minute',timestamp_column)),'5m') as interval_alias FROM 
    TABLE_NAME

Result:

interval_alias       
-------------------    
2010-11-16 10:30:00  
2010-11-16 10:35:00
2010-11-16 10:40:00   
2010-11-16 10:45:00
2010-11-16 10:50:00   
2010-11-16 10:55:00   

Now to get the result with interval with zero occurrences we just outer join both result sets.

    SELECT series.minute as interval,  coalesce(cnt.amnt,0) as count from 
       (
       SELECT count(*) amnt,
       to_timestamp(floor((extract('epoch' from timestamp_column) / 300 )) * 300)
       AT TIME ZONE 'UTC' as interval_alias
       from TABLE_NAME  group by interval_alias
       ) cnt
    
    RIGHT JOIN 
       (    
       SELECT generate_series(min(date_trunc('hour',timestamp_column)),
       max(date_trunc('minute',timestamp_column)),'5m') as minute from TABLE_NAME 
       ) series
  on series.minute = cnt.interval_alias

The end result will include the series with all 5 minute intervals even those that have no values.

interval             count
-------------------  ----  
2010-11-16 10:30:00  2
2010-11-16 10:35:00  10
2010-11-16 10:40:00  0
2010-11-16 10:45:00  8
2010-11-16 10:50:00  0 
2010-11-16 10:55:00  11 

The interval can be easily changed by adjusting the last parameter of generate_series. In our case we use '5m' but it could be any interval we want.

Solution 3:

You should rather use GROUP BY UNIX_TIMESTAMP(time_stamp) DIV 300 instead of round(../300) because of the rounding I found that some records are counted into two grouped result sets.

Solution 4:

For postgres, I found it easier and more accurate to use the

date_trunc

function, like:

select name, sum(count), date_trunc('minute',timestamp) as timestamp
FROM table
WHERE xxx
GROUP BY name,date_trunc('minute',timestamp)
ORDER BY timestamp

You can provide various resolutions like 'minute','hour','day' etc... to date_trunc.