Hibernate，@ SequenceGenerator和allocationSize

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如何解决Hibernate，@ SequenceGenerator和alLOCATIOnSize？

绝对清楚…您所描述的内容与规范没有 任何 冲突。该规范讨论的是Hibernate分配给您的实体的值，而不是实际存储在数据库序列中的值。

However, there is the option to get the behavior you are looking for. First see my reply on Is there a way to dynamically choose a @GeneratedValue strategy using JPA Annotations and Hibernate? That will give you the basics. As long as you are set up to use that SequenceStyleGenerator, Hibernate will interpret alLOCATIOnSize using the “pooled optimizer” in the SequenceStyleGenerator. The “pooled optimizer” is for use with databases that allow an “increment” option on the creation of sequences (not all databases that support sequences support an increment). Anyway, read up about the varIoUs optimizer strategIEs there.

解决方法

@Entity
@Table(name = "users")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "USERS_SEQ")
    @SequenceGenerator(name = "USERS_SEQ",sequencename = "SEQUENCE_USERS")
    private Long id;
}

<persistence-unit name="testPU">
  <properties>
    <property name="hibernate.id.new_generator_mappings" value="true" />
  </properties>
</persistence-unit>