Обсуждение: Sum of events over an interval; how?

--- S Dawalt <shane.dawalt@wright.edu> wrote:
>   I have a number of records having a timestamp when
> something happened. I am trying to find the number
> of events (records) that happened per minute over an
> hour timespan. I just cannot figure out how to do
> this.  Maybe it's not possible?  Would a plpgsql
> function be a good idea so that the number of
> front-end/back-end requests is small?  I'm looking
> for some output (or maybe temp table) of:
>
> Time                Count
> 2/17/2002 22:00:00    4
> 2/17/2002 22:01:00    7
> 2/17/2002 22:02:00   14
> ....
>
>   Any help, even "Can't be done" is appreciated.
>
> Shane A. Dawalt

The following solution will give you a count for the
events where the count during the minute is greater
than zero:

The name of our timestamp field is event_dt.
The name of the event flag is flag.
The name of the table is events.

select date_trunc('minute', event_dt) as minutes,
count(flag) as flags from events
where date_trunc('hour', event_dt)='2002-01-08
23:00:00'
group by minutes;

The WHERE clause is certainly optional.  You may need
it if you want to limit your results to a specific
time period.  In this example, only events occuring
between 11:00 pm and midnight on January 8, 2002 would
be reported.

Best of luck,

Andrew Gould


__________________________________________________
Do You Yahoo!?
Yahoo! Sports - Coverage of the 2002 Olympic Games
http://sports.yahoo.com

It might help to have the structure of the table you're querying, like the
CREATE TABLE statement. Also what version of Postgres are you using?

Wes



S Dawalt <shane.dawalt@wright.edu>@postgresql.org on 02/18/2002 02:32:08 PM

Sent by:  pgsql-general-owner@postgresql.org


To:   pgsql-general@postgresql.org
cc:
Subject:  [GENERAL] Sum of events over an interval; how?



? I have a number of records having a  timestamp when something happened. I
am trying to find the number of events  (records)?that happened per minute
over an hour timespan. I just cannot  figure out how to do this.? Maybe
it's not possible?? Would a plpgsql  function be a good idea so that the
number of front-end/back-end requests is  small?? I'm looking for some
output (or maybe temp table) of:

Time???????????????  Count
2/17/2002 22:00:00??? 4
2/17/2002 22:01:00??? 7
2/17/2002 22:02:00???14
....

? Any help, even "Can't be done" is  appreciated.

Shane A.  Dawalt
********************************************
Network  Engineer
Wright State University
Dayton,? OH??  45435??? USA
Phone:? 937-775-4089
Email:? shane.dawalt@wright.edu

I couldn't find if PostgreSQL  supports turkish encoding.

will/does PostgreSQL support these code pages ?

*DOS Code Page 857
*Internet ISO 8859-9
*Windows Code Page 1254

Serkan