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 @inheritance strategy InheritanceType joined?
The joined subclass strategy implies that the fields of each class in the hierarchy are placed in their own tables and that the tables are joined to construct the result. The classes would look like follows: @Entity @Table(name = “persons”) @Inheritance(strategy = InheritanceType.
What are the types of inheritance models in Hibernate?
There are three inheritance mapping strategies defined in the hibernate:
- Table Per Hierarchy.
- Table Per Concrete class.
- Table Per Subclass.
What is table per subclass in Hibernate?
In case of table per subclass class, there will be three tables in the database, each representing a particular class. The joined-subclass subelement of class, specifies the subclass. The key sub-element of joined-subclass is used to generate the foreign key in the subclass mapped table.
What is polymorphic queries in Hibernate?
A query like: from Cat as cat. returns instances not only of Cat , but also of subclasses like DomesticCat . Hibernate queries may name any Java class or interface in the from clause. The query will return instances of all persistent classes that extend that class or implement the interface.
What join table strategy means in EJB?
JOINED strategy uses a different table for each class in the hierarchy. Each table only includes state declared in its class. Thus to load a subclass instance, the EJB persistence implementation must read from the subclass table as well as the table of each ancestor class, up to the base entity class.
Does hibernate use setters?
Hibernate will no longer use the getters and setters, but will access the fields directly via reflection, meaning if you have any special logic in your getters and setters, it will no longer be called.
What is collection mapping in hibernate?
Hibernate supports collection mapping as value type. In this mapping, the collection are mapped into a separate table. When we have to persist property of a class, which is of data type like integer, long, float etc. or objects of wrapper classes or Strings, these properties are stored in the table of class directly.
What is HQL in Hibernate?
Hibernate Query Language (HQL) is an object-oriented query language, similar to SQL, but instead of operating on tables and columns, HQL works with persistent objects and their properties. HQL queries are translated by Hibernate into conventional SQL queries, which in turns perform action on database.