Part 2, Chapter 10
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Table of content
This chapter explains the core mapping elements used by Hibernate and details the basic type and the identifier generators.
10. Mapping Types and Identifiers 10.1 Types 10.1.1 Primitive types 10.1.2 String types 10.1.3 Date and Time types 10.1.4 Numeric types 10.1.5 Binary types 10.1.6 UUID types 10.1.7 Other types 10.1.8 Custom types 10.2 Identifiers 10.2.1 UUID identifiers 10.2.1.1 The assigned generator 10.2.2 The legacy UUID generator 10.2.2.1 The newer UUID generator 10.2.3 Numerical identifiers 10.2.3.1 Identity generator 10.2.3.2 Sequence generator 10.2.3.3 Table generator 10.2.3.4 Optimizers 10.2.3.4.1 The hi/lo algorithm 10.2.3.4.2 The default sequence identifier generator 10.2.3.4.3 The default table identifier generator 10.2.3.4.4 The pooled optimizer 10.2.3.4.5 The pooled-lo optimizer 10.2.3.5 Optimizer gain 10.2.3.5.1 Sequence generator performance gain 10.2.3.5.2 Table generator performance gain 10.2.3.6 Identifier generator performance
The chapter explains the relationship between the three mapping elements used by JPA: basic types, embeddables, and entities.
Because database systems come with specific data types that are targeted towards high-performance, this chapter covers basic types and explains how you can map database-specific types to Hibernate entities.
The second part of this chapter is dedicated to entity identifiers. It covers
UUID and numerical identifiers and it goes through identity, sequence and table generator strategies.
It explains how the enhanced generators differ from the legacy ones, and it covers all major sequence identifier optimizes:
In the end, it shows which identifier generator is suitable for high-performance write-intensive applications, and why you should use the enhanced optimizers developed by Hibernate.