User Mapping

tip

On this page, <package> can be one of: web, mobile

The web and mobile packages contains a User Mapping module that aims to link user identifiers, namely domain_userid/device_user_id to user_id. The logic is to take the latest user_id per domain_userid/device_user_id.

The domain_userid/device_user_id is cookie/device based and therefore expires/changes over time, where as user_id is typically populated when a user logs in with your own internal identifier (dependent on your tracking implementation).

This mapping is applied to the sessions table by a post-hook which updates the stitched_user_id column with the latest mapping. If no mapping is present, the default value for stitched_user_id is the domain_userid/device_user_id. This process is known as session stitching, and effectively allows you to attribute logged-in and non-logged-in sessions back to a single user.

If required, this update operation can be disabled by setting in your dbt_project.yml file (selecting one of web/mobile, or both, as appropriate):

# dbt_project.yml
...
vars:
  snowplow_<package>:
    snowplow__session_stitching: false

User mapping is typically not a 'one size fits all' exercise. Depending on your tracking implementation, business needs and desired level of sophistication you may want to write bespoke logic. Please refer to this blog post for ideas.