What is discriminator value in Hibernate?

What is discriminator value in Hibernate?

Annotation Type DiscriminatorValue Specifies the value of the discriminator column for entities of the given type. The DiscriminatorValue annotation can only be specified on a concrete entity class. The discriminator value, if not defaulted, should be specified for each entity class in the hierarchy.

What is discriminator value in JPA?

The discriminator column is always in the table of the base entity. It holds a different value for records of each class, allowing the JPA runtime to determine what class of object each row represents. The DiscriminatorColumn annotation represents a discriminator column.

What is a discriminator value?

What is @MappedSuperClass in Hibernate?

java hibernate. According to the Hibernate docs, MappedSuperclass allows mapping inheritance, where the super class is not treated as an entity, and where polymorphic queries that fetch objects by the base class are not supported.

How do you find the value of the discriminator column?

The entity definition: @Entity(name=”Port”) @DiscriminatorColumn(name=”type”, discriminatorType=DiscriminatorType. STRING, length=10) @DiscriminatorValue(value=”port”) @Table(name=”vPorts”) @XmlRootElement(name=”port”) public class PortEntity { …

Which inheritance strategy is better in Hibernate?

Keep in mind when using default JPA/Hibernate annotations, Hibernate always fetch all of subclasses. If you have a single hierarchy, prefer To use Single Table Inheritance strategy.

What is the use of @DiscriminatorColumn?

Discriminator is commonly used in SINGLE_TABLE inheritance because you need a column to identify the type of the record. Example: You have a class Student and 2 sub-classes: GoodStudent and BadStudent.

What is FetchType lazy in hibernate?

The FetchType. LAZY tells Hibernate to only fetch the related entities from the database when you use the relationship. This is a good idea in general because there’s no reason to select entities you don’t need for your uses case. You can see an example of a lazily fetched relationship in the following code snippets.

What is difference between Cascade and inverse in hibernate?

The property “Cascade” is used to define if update/delete method that applies to one object equally applies to a related one. “inverse”, however, is a property that defines which object is responsible for maintaining the relationship with another object.

Is a mapping requires discriminator column?

So, you don’t necessarily need a discriminator column. The value in this column identifies the entity class to which each record shall be mapped. By default, Hibernate uses the same approach.