I have a stream that updates every minute with a trigger that updates
another table with information from the stream. That way I'm constantly
updated with no need to run a script to update before I want a report.
Clifford
On Sun, Oct 1, 2017 at 10:08 AM, Melvin Davidson <melvin6...@gmail.com>
wrote:
>
>
> On Sun, Oct 1, 2017 at 4:17 AM, Khalil Khamlichi <
> khamlichi.kha...@gmail.com> wrote:
>
>> Hi everyone,
>>
>> I have a data stream of a call center application coming in to postgres
>> in this format :
>>
>> user_name, user_status, event_time
>>
>> 'user1', 'ready', '2017-01-01 10:00:00'
>> 'user1', 'talking', '2017-01-01 10:02:00'
>> 'user1', 'after_call', '2017-01-01 10:07:00'
>> 'user1', 'ready', '2017-01-01 10:08:00'
>> 'user1', 'talking', '2017-01-01 10:10:00'
>> 'user1', 'after_call', '2017-01-01 10:15:00'
>> 'user1', 'paused', '2017-01-01 10:20:00'
>> ...
>> ...
>>
>> so as you see each new insert of an "event" is in fact the start_time of
>> that event and also the end_time of the previous one so should be used to
>> calculate the duration of this previous one.
>>
>> What is the best way to get user_status statistics like total duration,
>> frequency, avg ...etc , does any body have an experience with this sort of
>> data streams ?
>>
>>
>> Thanks in advance.
>>
>
> Just a suggestion, but here is what I would do.
> First, create your tables similar to as follows
>
> CREATE TABLE status
> (
> call_status varchar(10) NOT NULL,
> CONSTRAINT status_pk PRIMARY KEY (call_status)
> );
>
> INSERT INTO status
> (call_status)
> VALUES
> ('ready'),
> ('talking'),
> ('after_call');
>
> CREATE TABLE user_sessions
> (
> username name NOT NULL,
> session_id bigint NOT NULL,
> call_status varchar(10) NOT NULL,
> call_time timestamp NOT NULL,
> CONSTRAINT user_sessions_pk PRIMARY KEY (username,
> session_id,call_status),
> CONSTRAINT user_sessions_fk_status FOREIGN KEY (call_status)
> REFERENCES status(call_status)
> );
>
> Next, you will need to generate a unique session_id for each
> user, but only for when call_status is 'ready'. So probably
> a table of the form:
>
> CREATE TABLE current_session
> (
> username name NOT NULL,
> session_id serial NOT NULL,
> CONSTRAINT current_session_pk PRIMARY KEY (username)
> );
>
> Then all you need to do is:
> 1. Update current_session and get the new session_id each time a user
> connects (call_status = 'ready'.
> Probably best to use a BEFORE trigger to do this, but you will need to
> code it yourself.
>
> 2. You can then do
>
> SELECT username,
> age ( (SELECT call_time FROM current_session WHERE call_status =
> 'talking'),
> ( SELECT call_time FROM current_session WHERE call_status =
> 'after_call')
> ) as duration
> FROM user_sessions
> WHERE username = '*actual_user_name*'
> AND session_id = *actual_session_id*;
>
> You can use similar queries for avg and frequency.
>
> --
> *Melvin Davidson*
> I reserve the right to fantasize. Whether or not you
> wish to share my fantasy is entirely up to you.
>
--
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