Most destinations on the Segment Platform are built up around a user model. They assume that a user will have a single
userId. Further, most Destinations are not built to handle anonymous traffic.
By default, we do not sync the output of the Identity Graph to Destinations. However, Segment computed traits and audiences are based on the entire user profile, including anonymous and merged data. We sync the value of these computations (e.g.
blog_posts_ready_30_days: 10) using all
userIds on the profile.
For Destinations that support an
alias call (e.g. Mixpanel), we have the option to emit an
alias call on merge.