Java Hibernate 在使用序列时生成负 id 值
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Hibernate generates negative id values when using a sequence
提问by Tomer
I have a class with the following definition:
我有一个具有以下定义的类：
@Id
@SequenceGenerator(name = "SEQ_ACE_WORKERS_QUEUE_STATS_ID", sequenceName = "SEQ_ACE_WORKERS_QUEUE_STATS_ID", allocationSize = 500)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_ACE_WORKERS_QUEUE_STATS_ID")
@Column(name = "ID")
private long Id;
When we ran it on Jboss 4.2.3 it worked fine and generated the proper ID's (starting from 1000+)
当我们在 Jboss 4.2.3 上运行它时，它运行良好并生成了正确的 ID（从 1000+ 开始）
Now we moved to jboss 7.1.1 and it generates negative ID's! (starting from -498 and going up)
现在我们转移到 jboss 7.1.1，它会生成负 ID！（从-498开始向上）
Any idea why this might happen?
知道为什么会发生这种情况吗？
采纳答案by jrm
I just ran into this issue when migrating from JBoss 6.1 to JBoss 7.1.
我刚从 JBoss 6.1 迁移到 JBoss 7.1 时遇到了这个问题。
According to the JBoss AS 7.1 JPA documentation ( https://docs.jboss.org/author/display/AS71/JPA+Reference+Guide#JPAReferenceGuide-Persistenceunitproperties),
根据 JBoss AS 7.1 JPA 文档（https://docs.jboss.org/author/display/AS71/JPA+Reference+Guide#JPAReferenceGuide-Persistenceunitproperties），
JBoss 7.1 automatically sets several hibernate properties. One of the properties being set is hibernate.id.new_generator_mappingswhich activates new ID generators that use different algorithms and are not backwards compatible. Setting this property to false in your persistence.xml file will restore the old ID generator behavior.
JBoss 7.1 会自动设置几个休眠属性。正在设置的属性之一是hibernate.id.new_generator_mappings激活使用不同算法且不向后兼容的新 ID 生成器。在您的persistence.xml 文件中将此属性设置为false 将恢复旧的ID 生成器行为。
The hibernate 4 documentation also has information regarding the new ID generators: http://docs.jboss.org/hibernate/core/4.0/manual/en-US/html_single/#mapping-declaration-id-generator.
hibernate 4 文档还包含有关新 ID 生成器的信息：http: //docs.jboss.org/hibernate/core/4.0/manual/en-US/html_single/#mapping-declaration-id-generator。
The hibernate documentation clearly states that the new ID generators are not enabled by default, but, as noted above, JBoss 7.1 is automatically enabling them.
hibernate 文档明确指出默认情况下未启用新的 ID 生成器，但如上所述，JBoss 7.1 会自动启用它们。
回答by falsarella
Setting hibernate.id.new_generator_mappingsto falsein my persistence.xmlwas just the first part of the solution to my problem:
设置hibernate.id.new_generator_mappings为falsein mypersistence.xml只是解决我的问题的第一部分：
To completely solve the problem I added the allocationSizeto 1in the @SequenceGenerator(which I was omitting).
为了彻底解决问题我添加allocationSize到1在@SequenceGenerator（我被省略）。
回答by skay
The new behaviour is the followings:
新行为如下：
AllocationSizeis a range of primary key values reserved for Hibernate.
And the select seq.nextvalfrom dual will be done only after hibernate consumed this range of primary keys.
AllocationSize是为 Hibernate 保留的一系列主键值。并且seq.nextval只有在休眠消耗了这个范围的主键后才会从双中选择。
So you mustdeclare the same value on both allocationSize(Hibernate) and sequence increment by(DB)
所以你必须在allocationSize(Hibernate) 和序列increment by(DB)上声明相同的值
When explicitly set allocationSize=500, e.g. on Oracle
当显式设置时allocationSize=500，例如在 Oracle 上
create sequence SEQ_ACE_WORKERS_QUEUE_STATS_ID
MINVALUE 1
MAXVALUE 999999999999999999999999999
START WITH 1
INCREMENT BY 500
NOCACHE
NOCYCLE;
Otherwise, you'll notice negative values or constraint errors raised from your DB because of primary key collisions.
否则，您会注意到由于主键冲突而从数据库中引发的负值或约束错误。
When the app server is restarted, you'll notice the 'jump' between the latest primary key allocated, and the 'newly' sequence number selected at restart.
当应用服务器重新启动时，您会注意到分配的最新主键和重新启动时选择的“新”序列号之间的“跳转”。
Final comment: default value is 50. So if you don't specify allocationSizeon the Hibernate side, you mustdeclare increment by50 on the DB side.
最后评论：默认值是50。所以如果你allocationSize在Hibernate端没有指定，你必须increment by在DB端声明50。
