生成Hibernate_sequence表 [英] Hibernate_sequence table is generated

问题描述

我有id列生成策略AUTO，我想知道，为什么MySql生成hibernate_sequence表？我认为hibernate将选择IDENTITY id生成策略

I have id column with generated strategy AUTO, I'm wondering, why MySql generate hibernate_sequence table? I supposed that hibernate will pick IDENTITY id generating strategy

<mapped-superclass class="com.cl.xlp.model.data.Identity">
    <attributes>
        <id name="id">
            <column name="id" />
            <generated-value strategy="AUTO" />
        </id>
    </attributes>
</mapped-superclass>

Hibernate属性

Hibernate properties

hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.hbm2ddl.auto=update

Mysql连接器版本

Mysql connector version

version.mysql.connector>5.1.39</version.mysql.connector>

Mysql服务器版本是5.6.12

Mysql server version is 5.6.12

推荐答案

Hibernate解释自动生成类型的方式已经从Hibernate 5.0开始改变。

The way Hibernate interprets AUTO generation type has changed starting with Hibernate version 5.0.

当使用Hibernate v 4.0和Generation Type作为 AUTO ，特别是对于MySql，Hibernate会选择 IDENTITY 策略（因此使用 AUTO_INCREMENT feature）用于为相关表生成ID。

When using Hibernate v 4.0 and Generation Type as AUTO, specifically for MySql, Hibernate would choose the IDENTITY strategy (and thus use the AUTO_INCREMENT feature) for generating IDs for the table in question.

从版本5.0开始，当Generation Type被选为AUTO时，Hibernate使用 SequenceStyleGenerator 无论数据库如何。在MySql的情况下，Hibernate使用表模拟一个序列，这就是你看到hibernate_sequence表的原因。 MySql本身不支持标准序列类型。

Starting with version 5.0 when Generation Type is selected as AUTO, Hibernate uses SequenceStyleGenerator regardless of the database. In case of MySql Hibernate emulates a sequence using a table and is why you are seeing the hibernate_sequence table. MySql doesn't support the standard sequence type natively.

引用

• < a href =http://docs.jboss.org/hibernate/orm/5.0/userguide/html_single/Hibernate_User_Guide.html#identifiers-generators-auto =noreferrer> http://docs.jboss.org/ hibernate / orm / 5.0 / userguide / html_single / Hibernate_User_Guide.html＃identifierss- generators-auto


• https://www.thoughts-on-java.org/5-things-你需要知道什么时候使用hibernate-with-mysql /

• http://docs.jboss.org/hibernate/orm/5.0/userguide/html_single/Hibernate_User_Guide.html#identifiers-generators-auto
• https://www.thoughts-on-java.org/5-things-you-need-to-know-when-using-hibernate-with-mysql/

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