Salesforce: Some Insights

What? Polymorphic key is a relationship field which can relate to more than one type of object as parent. Unlike Lookup and Master-detail relationships which are related to a single object, Polymorphic keys can refer to multiple objects. Where? As of date, Polymorphic keys cannot be created by developers. They are available for specific objects out of the box for e.g. WHOID and WHATID in Task and Event objects. Why? As we know, Salesforce’s data model is strictly relationship based, and the type of objects at both the ends of the relationship is fixed. So, if an object is to be related with multiple objects, then a separate relationship field has to be created for each relationship. Polymorphic keys are required to maintain relationship with multiple types, for e.g. task/ event might be related with various type of records viz. Account, Contact etc. So, a polymorphic key helps in establishing unique access to such disparate relationships. How? Polymorphic keys ...