The strategy and the discriminator column are only specified in the root of an entity class hierarchy or sub hierarchy in which a different inheritance strategy is applied It is specified on the entity class that is the root of the entity class – Is used to define the discriminator column for the SINGLE_TABLE and JOINED inheritance mapping strategies. Hence we have used some annotations to make it as the – Defines the inheritance strategy to be used for an entity class hierarchy. The Person class is the root of hierarchy. Constructors and Getter/Setter methods, Create Database Table to persist Class Hierarchy DisadvantageĬhanges to members of the hierarchy require column to be altered, added or removed from the table. This hierarchy offers the best performance even for in the deep hierarchy since single select may suffice. A discriminator is a key to uniquely identify the base type of the class hierarchy.įollowing are the advantages and disadvantages of One Table per Class Hierarchy scheme. In One Table per Class Hierarchy scheme, we store all the class hierarchy in a single SQL table. The properties of each class are: * class Person Suppose we have a class Person with subclass Employee. But you need to choose certain mapping strategy based on your needs. Hibernate can help you map such Objects with relational tables. Relational model supports only “has a” relationship between two entities. Object oriented systems can model both “is a” and “has a” relationship. Inheritance is one of the most visible facets of Object-relational mismatch. It is possible to implement Inheritance in Java.
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