If you have enabled both Dynamic Re-Ranking (DRR) and Personalization, the engine will not apply them concurrently. The default behaviour is:
- Personalization will be applied if:
- the user has a corresponding user profile (ie. profile found) and
- the user profile's affinities match the records returned by the search (ie. profile applied)
- DRR will be applied if personalzation is not applied, for example if:
- The user is first-time visitor
- The user profile's affinities do not match the returned records
This behaviour changes when using distinct (ie. distinct:true or distinct>1).
When distinct is enabled, if the user is found, DRR will not be applied to results, even if the user profile's affinities do not match the records returned by the search.
Since user profiles are created during their first session (ie. a profile can be found), but personalisation is only applied once the user is considered "returning", this behaviour (where DRR is not applied when distinct:true) can occur during a user's very first session.