Re: Group by range in hour of day

Assuming 3 things

Table name - test
Column names - start_time, end_time
Added an id column (int) to distinguish each record in the table

You can go with this..... (my apologies for formatting issues)

with
slots as (
select *
from generate_series(0,1439) as s(slot)
),
slots_hours as (
select slot,
slot / 60 as hour
from slots
),
minutes as (
select id,
date_part('hour', start_time) * 60 + date_part('minute',
start_time) as start_minute,
date_part('hour', end_time) * 60 + date_part('minute',
end_time) as end_minute
from test
),
minute_slots as (
select id,
slot,
hour
from minutes
join slots_hours
on minutes.start_minute <= slots_hours.slot
and minutes.end_minute > slots_hours.slot
)
select hour,
count(*) / 60.0 as sum,
count(distinct id) as count
from minute_slots
group by hour

I'm certain there are more elegant solutions possible - but you can grasp
each step this way.

John

On Mon, Mar 16, 2015 at 2:57 PM, Israel Brewster <israel(at)ravnalaska(dot)net>
wrote:

> I have a table with two timestamp columns for the start time and end time
> of each record (call them start and end).I'm trying to figure out if there
> is a way to group these records by "hour of day", that is the record should
> be included in the group if the hour of the day for the group falls
> anywhere in the range [start,end]. Obviously each record may well fall into
> multiple groups under this scenario.
>
> The goal here is to figure out, for each hour of the day, a) what is the
> total number of "active" records for that hour, and b) what is the total
> "active" time for those records during the hour, with an ultimate goal of
> figuring out the average active time per record per hour.
>
> So, for simplified example, if the table contained three records:
>
> start | end
> -----------------------------------------------------
> 2015-03-15 08:15 | 2015-03-15 10:45
> 2015-03-15 09:30 | 2015-03-15 10:15
> 2015-03-15 10:30 | 2015-03-15 11:30
>
>
> Then the results should break out something like this:
>
> hour | count | sum
> -----------------------------
> 8 | 1 | 0.75
> 9 | 2 | 1.5
> 10 | 3 | 1.5
> 11 | 1 | 0.5
>
> I can then easily manipulate these values to get my ultimate goal of the
> average, which would of course always be less than or equal to 1. Is this
> doable in postgress? Or would it be a better idea to simply pull the raw
> data and post-process in code? Thanks.
>
> -----------------------------------------------
> Israel Brewster
> Systems Analyst II
> Ravn Alaska
> 5245 Airport Industrial Rd
> Fairbanks, AK 99709
> (907) 450-7293
> -----------------------------------------------
>
>
>
>
>
>