Hibernate注解映射sequence时出现无序增长问题

    通过Hibernate注解的方式映射oracel数据库的sequence主键生成器时，出现增加数据时sequence无序增长的问题，配置如下：

@SequenceGenerator(name = "SEQ_DM_SERVICE_MODEL", sequenceName = SEQ_DM_SERVICE_MODEL")
@Id
@GeneratedValue(strategy = SEQUENCE, generator = "SEQ_DM_SERVICE_MODEL")
@Column(name = "SERVICE_MODEL_ID", unique = true, nullable = false, precision = 10, scale = 0)
public Long getId() {
	return this.id;
}

此时主键id的增长是按照hibernate自动处理的方式，而并非数据库中定义的sequence来处理。必须加allocationSize=1,initialValue=1这两项配置才可以解决上述问题。如下：

@SequenceGenerator(name = "generator",allocationSize=1,initialValue=1, sequenceName = "SEQ_DM_SERVICE_MODEL")