Analytics · Advanced Topics · Sessionization

The following advanced topics are covered in this section:


A session is a period devoted to a user browsing your website(s). Sessionization is the process in which all hits that were analyticsd will be grouped to sessions. A user can have multiple sessions and each session can contain multiple pageviews or other hits. However it is also possible that a user has only a single session with a single hit.

What does sessionization do?

During sessionization Analytics will group the hits of a user into one or more sessions. Hits will be grouped in the same session when:

  • the time between 2 hits is less than 30 minutes, and
  • the user did not re-visit the website (referring URL is not self or owned) Analytics corrects (accidental) double clicks on a campaign

Only sessions that are closed can be sessionized. Sessionization can therefore never be realtime.

Where is the sessionization information stored?

All the information is stored in the session field of the hits table.

How is sessionization done?

Every hour or so the analytics backend connects to your BigQuery instance and looks for the hits table (usually hits) in the analytics dataset (usually osb_analytics). It will first select all the unsessionized hits, sessionize them and update the session field in the hits table with the information.

What information is calculated with sessionization?

Per session the following information is calculated:

Session duration in seconds · session.duration
(Partial) seconds between the first and the last hit (not just pageview)
Session number · session.number
which index number does the session have? In case the visitor doesn't visit the website for longer than 6 months, numbering will restart at 1 again
Page number ·
Index number of the pageview in the session
Page view time ·
(Partial) seconds between the pageview and the next pageview. Is null is this is the last pageview.
Is last page? ·
Boolean to determine if the page is the last page (True) or not (False).
Marketing channel information of the first hit · session.marketing_channel.*
Contains the marketing channel information duplicated on all the hits that belong to that session. You need this to determine the marketing channel of your conversions or other goals that don't happen on the first page.
Referrer information of the first hit · session.referrer.*
Contains the referrer categorization of the first hit, duplicated across the whole visit. You need this to determine the traffic source of your conversions or other goals that don't happen on the first page.
Path information · session.paths.*
Contains the hit id's of the previous page, previous hit, next page and next hit.

API reference

You can send server side calls to Analytics. Contact us to receive the full API reference and documentation on this subject.