Re: dynamic interval in plpgsql
От | Thilo Hille |
---|---|
Тема | Re: dynamic interval in plpgsql |
Дата | |
Msg-id | 40696D89.3080203@resourcery.de обсуждение исходный текст |
Ответ на | Re: dynamic interval in plpgsql (Josh Berkus <josh@agliodbs.com>) |
Список | pgsql-novice |
Hello Josh, lets take a table of the following structure: table events: event string | start timestamp | duration int (interval in seconds) "event1" | '2004-03-30 08:00:00' | 7200 "event1" | '2004-03-30 13:00:00' | 32400 now i want to do some dataprocessing weighting how long an event was occurring in a different time of the day. lets say time1= 00:00:00 - 09:00:00 weight: seconds*1 time2= 12:00:00 - 18:00:00 weight: seconds*2 time3= 20:00:00 - 23:00:00 weight: seconds*3 for instance: "event1" should return (3600*1) as it overlaps with time1 for 1 hour. "event2" should return (18000*1)+(7200*2) as it overlaps with time1 for 5 hour and time2 for 2 hours. my idea was something like this: (this is notworking code! its just to give the idea, i trashed my orginal attempts accidentally) create function eventweight(timestamp,int) return int as' event_start=$1 event_end=interval '$2 seconds' // how can i do this with plpgsql? day_start=date_trunc('day',$1) time_start[0]=daystart +'00:00:00'::time time_end[0]=daystart +'09:00:00'::time time_weight[0]=1 time_start[1]=daystart +'12:00:00'::time time_end[1]=daystart +'18:00:00'::time time_weight[1]=2 time_start[2]=daystart +'20:00:00'::time time_end[2]=daystart +'23:00:00'::time time_weight[1]=3 current=0 while current<size(time_start) if time_start[current]<=event_start && time_end[current]>=event_end ret+=extract(epoche from (time_end[current]-time_start[current])::timestamp)::int*time_weight[current] elseif //check & calculate fractions..... ... fi elihw return ret ' language 'menonothin' i made a similiar function with plpython. i converted the timestamp to epoche to get them into python as float. but know i have some timezone issues. thats why i thought this would be best done with plpgsql in the first place :( what i was not getting: "event_end=interval '$2 seconds'" i tried several attempts with different quotes but i didnt find out howto assign a variable instead of a fixed string to the INTERVAL command using plpgsql. thanks & regards thilo Josh Berkus wrote: >Thilo, > > > >>i work on a stored procedure which does some timespecific calculations >>in plpgsql. >>in a loop i want to increase a timestamp by a changing interval. but i >>found no way to assign a variable to INTERVAL . >>finally i used plpython for the function but i still wonder if it could >>be done with plpgsql? >> >> > >I'm sure this is possible, but from your description I can't figure out what >you're trying to do. Please be more explicit. > > >
В списке pgsql-novice по дате отправления: