How to Best Map Object Inheritance in JPA/Hibernate

Introduction

Object inheritance can be mapped in 3 ways in JPA/Hibernate.

• SINGLE_TABLE
• TABLE_PER_CLASS
• JOINED

SINGLE_TABLE - @Inheritance(strategy = InheritanceType.SINGLE_TABLE)

All Inheritance Java Classes are stored in one big database table.

Default @Inheritance(strategy = InheritanceType.SINGLE_TABLE)

pros

• Faster query, since no joining of tables

cons

• Data Integrity. Cannot uphold NOT NULL constraints, etc, but can be enforced via a CHECK of TRIGGER. Bean Validation can improve, but does not help if either integrate directly with the database.
• Works when smaller set of different inhereted class, but single table grows

TABLE_PER_CLASS - @MappedSuperclass

https://vladmihalcea.com/how-to-inherit-properties-from-a-base-class-entity-using-mappedsuperclass-with-jpa-and-hibernate/

pros

• Can enforce NOT NULL constraints, etc

cons

• You rarely need to joind inhereted java class, so no real cons

JOINED - @Inheritance(strategy = InheritanceType.JOINED)

https://vladmihalcea.com/the-best-way-to-use-entity-inheritance-with-jpa-and-hibernate/

Do no use, no efficient SQL.

Summary

Use TABLE_PER_CLASS with @MappedSuperclass.