Re: How to fetch values at regular hours?

Goran Hasse wrote:
> Hello all!
>
> I am logging my electricity meeter every five minute!
>
> But the problem is that I would like to get values *just before* every
> hour - like
>
> select * from counter_log_view where name='CNT-3' and timestamp <
> '2010-05-23 22:00:00' order by timestamp desc limit 1;
> name | timestamp | count
> -------+----------------------------+-------
> CNT-3 | 2010-05-23 21:53:20.844422 | 69
> (1 rad)
>
> But I don't want to do a lot of selections and gather all the data in
> a file.
> Is there any better way to create the query so that I get the values
> just before
> every hour?

wild guess, untested.. something like...

select * from counter_log_view where name = 'CNT-3' and extract(minute
from timestamp) >= 55 order by timestamp;