Session unification

Understand what session unification is, and how to turn it ON and OFF.

Session unification is a User ID setting that allows hits collected before the User ID is assigned to be associated with the ID, so long as those hits happen within the same session in which a specific ID value is assigned for the first time. When session unification is OFF, only hits that are collected when the User ID is explicitly assigned can be associated with an ID.

In this article:

Session unification is a User ID setting that allows hits collected before the User ID is assigned to be associated with the ID, so long as those hits happen within the same session in which a specific ID value is assigned for the first time. When session unification is OFF, only hits that are collected when the User ID is explicitly assigned can be associated with an ID.

To turn session unification ON/OFF

When you set up the User ID feature, session unification is ON by default. You can turn the setting OFF during set up, or you can follow these instructions to turn it ON/OFF anytime.

To turn session unification ON/OFF on a User ID property:

  1. Sign in to your Google Analytics account.
  2. Select the Admin tab
  3. From the ACCOUNT and PROPERTY columns, use the drop-down menus to select first an account and then a property to work with.
  4. Click User ID.
  5. Click Step 2.
  6. Click the switch to toggle ON/OFF.

How session unification affects your data

These examples compare which sessions and session data can be associated with a user ID when session unification is either ON or OFF.

Although you can use Google Analytics for many different technologies and implement the User ID feature in many ways, these examples demonstrate session unification in a situation where Google Analytics is used on a website and the User ID is assigned through an account sign in.

In the illustrations, each session is represented by a rectangle, and the numbers indicate different sessions. A filled-in rectangle indicates when a user ID is assigned. For example, a user ID was assigned for the entire duration of sessions 3 and 6, but only for a portion of sessions 2 and 4. The dotted lines indicate which sessions (or portions of a session) are associated with a user ID.

When session unification is OFF

Illustration of session data that can be connected together when session stitching is off.
Hits from the session in which the User ID is set are NOT associated with an ID when session unification is off.
Click to get details on what happens in each session
  • Session 1: User visits your website, but there’s no account sign in. The user ID is not assigned, and no hits are associated with an ID.
  • Session 2: User visits your website, and signs in to an account halfway through the session. A specific ID is assigned. Hits collected before the ID is assigned are not associated with the ID. Hits that are collected after the ID is assigned are associated with the ID.
  • Session 3: User is signed in for the entire length of the session. The user ID is assigned, and all hits from the session are associated with the ID.
  • Session 4: User is signed in when the session begins, but signed out halfway through. All hits collected while the user was signed in are associated with the ID. All hits collected after the sign out are not associated with the ID.
  • Session 5: User is signed out for the entire session. No user ID is assigned, and no hits are associated with an ID.
  • Session 6: User is signed in for the entire length of the session. All hits from the session are associated with the ID.

When session unification is ON

Illustration of session data that can be connected together when session stitching is on.
Hits from the entire session in which the User ID is set are associated with an ID when session unification is on.
Click to get details on what happens in each session
  • Session 1: User visits your website, but there’s no account sign in. The user ID is not assigned, and no hits are associated with an ID.
  • Session 2: User visits your website, and signs in to an account halfway through the session. A specific ID is assigned. All hits from this session are associated with the ID.
  • Session 3: User is signed in for the entire length of the session. The user ID is assigned, and all hits from the session are associated with the ID.
  • Session 4: User is signed in when the session begins, but signed out halfway through. All hits collected while the user was signed in are associated with the ID. All hits collected after the sign out are not associated with the ID.
  • Session 5: User is signed out for the entire session. No user ID is assigned, and no hits are associated with the ID.
  • Session 6: User is signed in for the entire length of the session. The user ID is assigned, and all hits from the session are associated with the ID.
Session unification is completed during daily data processing. Processing begins at 5am each day, based on the western most timezone selected in any reporting view that is associated with the property.
Session unification is only available for User ID enabled properties. Learn more about: