date_trunc 5 minute interval in PostgreSQL [duplicate]

问题

Possible Duplicate:
What is the fastest way to truncate timestamps to 5 minutes in Postgres?
Postgresql SQL GROUP BY time interval with arbitrary accuracy (down to milli seconds)

I want to aggregate data at a 5 minute interval in PostgreSQL. If I use the date_trunc() function, I can aggregate data at an hourly, monthly, daily, weekly, etc. interval but not a specific interval like 5 minute or 5 days.

select date_trunc('hour', date1), count(*) from table1 group by 1;

Does anyone know how we can achieve this in PostgreSQL?

Any help is appreciated.

回答1:

SELECT date_trunc('hour', date1) AS hour_stump
      ,(extract(minute FROM date1)::int / 5) AS min5_slot
      ,count(*)
FROM   table1
GROUP  BY 1, 2
ORDER  BY 1, 2;

You could GROUP BY two columns: a timestamp truncated to the hour and a 5-minute-slot.

The example produces slots 0 - 11. Add 1 if you prefer 1 - 12.
I cast the result of extract() to integer, so the division / 5 truncates fractional digits. The result:
minute 0 - 4 -> slot 0
minute 5 - 9 -> slot 1
etc.

This query only returns values for those 5-minute slots where values are found. If you want a value for every slot or if you want a running sum over 5-minute slots, consider this related answer:
PostgreSQL: running count of rows for a query 'by minute'

回答2:

Here's a simple query you can either wrap in a function or cut and paste all over the place:

select now()::timestamp(0), (extract(epoch from now()::timestamptz(0)-date_trunc('d',now()))::int)/60;

It'll give you the current time, and a number from 0 to the n-1 where n=60 here. To make it every 5 minutes, make that number 300 and so on. It groups by the seconds since the start of the day. To make it group by seconds since year begin, hour begin, or whatever else, change the 'd' in the date_trunc.

来源：https://stackoverflow.com/questions/12165827/date-trunc-5-minute-interval-in-postgresql

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sql

postgresql

datetime

aggregate-functions