Postgres group by timestamp into 6 hourly buckets

Question

I have the following simple table:

ID      TIMESTAMP               VALUE
4   2011-05-27 15:50:04 1253
5   2011-05-27 15:55:02 1304
6   2011-05-27 16:00:02 1322
7         


        

Answer 1

I think grouping the integer value of the quotient of the (Hour of your timestamp / 6) should help. Try it and see if it helps. Your group by should be something like

group by year, month, day, trunc(EXTRACT(hour from TIMESTAMP) / 6)

The logic behind this is that when the hour part of the date is divided by 6, the int values can only be

    0 - 0:00 - 5:59:59
    1 - 6:00 - 11:59:59
    2 - 12:00 - 17:59:59
    3 - 18:00 - 23:59:59

Grouping using this should put your data into 4 groups per day, which is what you need.