Session Duration and Time on Page calculation usin

Question

I have some data in web_event table of Netezza in this below format.

vstr_id  |  sessn_id  |  sessn_ts            | wbpg_nm 
V1       |  V1S1      |  02-02-2015 09:20:00 | /home/login
V1       |  V1S1      |  02-02-2015 09:30:00 | /home/contacts
V1       |  V1S1      |  02-02-2015 09:50:00 | /home/search
V2       |  V2S1      |  02-02-2015 09:10:00 | /home
V2       |  V2S1      |  02-02-2015 09:15:00 | /home/apps
V2       |  V2S2      |  02-02-2015 09:20:00 | /home/news
V2       |  V2S2      |  02-02-2015 09:23:00 | /home/news/internal

This is my source table.

I am trying to use that web_event table and create another table like below.

I want the sessn_durtn table and time_on_pg table to be loaded like below.

1) sessn_durtn column : this should be time difference between session start event and session end event according to sorted time field. It can be in represented in minutes or seconds

I am trying to to do 

Insert into sessn_durtn (select VSTR_ID,
           SESSN_ID,
           ????? as sessn_durtn,
           from web_event)

vstr_id  |  sessn_id  | seesn_durtn
V1       |  V1S1      | 30mins       
V2       |  V2S1      | 5mins                
V2       |  V2S2      | 3mins          

2) time_on_page column : It is the time difference between the current page and next page and the last page of the session can have 0 secs. It can be represented in minutes or seconds.

Insert into time_on_pg (select VSTR_ID,
           SESSN_ID,
           sessn_ts,
           WBPG_NM,
           ????? as time_on_page
           from web_event)

vstr_id  |  sessn_id  |  sessn_ts            | wbpg_nm              | time_on_page
V1       |  V1S1      |  02-02-2015 09:20:00 | /home/login          |   10mins
V1       |  V1S1      |  02-02-2015 09:30:00 | /home/contacts       |   20mins
V1       |  V1S1      |  02-02-2015 09:50:00 | /home/search         |   0mins
V2       |  V2S1      |  02-02-2015 09:10:00 | /home                |   5mins
V2       |  V2S1      |  02-02-2015 09:15:00 | /home/apps           |   0mins
V2       |  V2S2      |  02-02-2015 09:20:00 | /home/news           |   3mins
V2       |  V2S2      |  02-02-2015 09:23:00 | /home/news/internal  |   0mins

How can we do this in Netezza or any SQL query?

Answer 1

For the session duration:

SELECT vstr_id, MAX(sessn_ts), MIN(sessn_ts), 
TIMESTAMPDIFF(MINUTE,MIN(sessn_ts),MAX(sessn_ts)) AS sessn_durtn
FROM `web_event`
GROUP BY vstr_id, sessn_id

And for the time on page (you don't have a record of the time they leave, so I can't get the time on page for the last page of the session, so I just set that to 0. If you have that data, you could insert it with a fixed wbpg_nm that won't collide with any others, maybe 'exit' or some such):

SELECT t1.*,
IFNULL(TIMESTAMPDIFF(MINUTE, t1.sessn_ts, t2.sessn_ts), 0) AS time_on_pg
FROM
(
    SELECT w1.*,
    @rownum := @rownum + 1 AS position
    FROM `web_event` w1
    JOIN (SELECT @rownum := 0) r
    ORDER BY vstr_id, sessn_id, sessn_ts
) t1
LEFT JOIN
(
    SELECT w1.*,
    @rownum2 := @rownum2 + 1 AS position
    FROM `web_event` w1
    JOIN (SELECT @rownum2 := 0) r
    ORDER BY vstr_id, sessn_id, sessn_ts
) t2
ON t1.vstr_id = t2.vstr_id 
AND t1.sessn_id = t2.sessn_id 
AND t1.position = t2.position - 1

Answer 2

Thank you So much for your time and effort.

Sessn_duration is correct and it works fine.

For time on page this is is a simpler working answer.

SELECT vstr_id,
       sessn_id,
       extract(epoch from (lag(event_ts) over (partition by vstr_id, sessn_id order by event_ts DESC) - event_ts)) AS tm_on_pg,
       wbpg_nm

from pagepath_poc;