Client Key is an optional way for Pulse Insights to store a persistent identifier associated with a user, which unlocks a few key features:
Client key can link different browsers (e.g., home vs. work), devices, and channels so that Pulse Insights can decision at the person-level. For example, if a personal has already answered a particular survey on a home browser, Pulse Insights wouldn't serve it again in a different browser or device that shares the same client key, because the person has already answered it. Without Client Key, Pulse Insights would see the different browsers as independent.
Often times, Client Key is a primary ID used to identify a user across systems in an organization. As such, it's used as a key to determine which record to update, say in a CRM system.
You can see Client Key values that were set in the current pageview in the PulseInsightsObject.
Client key values are also stored in local storage.
The client key is stored in PulseInsightsObject until an impression or submission occurs on that pageview.
identify_clientdoesn't generate its own network call.
Once set on a device, it needn't be redefined on subsequent pageviews or visits.
Client key data will be in the Client Key column of the XLS and CSV exports from console.
Yes. You only need to use Client Key if you want to use cross device linkage and frequency cap features. Integrations can be configured to utilize Context or Device data values as well.
Yes, in reporting and analysis, as the client key becomes associated with the Device UDID, including all past and future impressions and submissions. For decisioning (e.g., cross device frequency caps) and standard integrations, it is used going forward.