spring.jpa.hibernate.hbm2ddl和spring.jpa.hibernate.ddl之间的区别 [英] Difference between spring.jpa.hibernate.hbm2ddl and spring.jpa.hibernate.ddl

问题描述

spring.jpa.hibernate.hbm2ddl 和 spring.jpa.hibernate.ddl 有什么区别?

What is the difference between spring.jpa.hibernate.hbm2ddl and spring.jpa.hibernate.ddl?

我在以下问题中发现:什么是OP在属性中同时使用了spring.datasource.initialization-mode?的可能值，但是hbm2ddl的来源似乎直接休眠而不是Spring Data Jpa.

I have found in this question: What are the possible values of spring.datasource.initialization-mode? that OP is using both in properties, however it seems like the origin of hbm2ddl is hibernate directly not Spring Data Jpa.

尽管如此，从另一个OP中读取答案，它看起来像只是传递.

Nevertheless, reading the answer from another OP, it looks like pass-through only.

但是，在我们使用mariadb的商业项目中，当我们没有通过 spring.jpa.hibernate.hbm2ddl.auto=create 正常关闭Spring Boot应用程序时，再次运行该应用程序时，它将删除旧数据并从头开始创建所有内容.另一方面，使用 spring.jpa.hibernate.ddl.auto=create 每秒运行一次(在没有正常关闭应用程序之后)会导致关键约束异常(数据库在创建之前没有被删除)

However in our commercial project with mariadb, when we do not close our spring boot application gracefully with spring.jpa.hibernate.hbm2ddl.auto=create, when the application is run again, it deletes old data and creates everything from scratch. On the other hand with spring.jpa.hibernate.ddl.auto=create every second run (after no graceful application shutdown) causes key constraint exceptions (DB is not being dropper before creation)

推荐答案

1. 从此
   • 默认情况下，仅当您使用嵌入式数据库(H2，HSQL或Derby)时，才会自动创建JPA数据库.

   您可以使用spring.jpa.*属性来显式配置JPA设置.例如，要创建和删除表，可以将以下行添加到application.properties:

   You can explicitly configure JPA settings by using spring.jpa.* properties. For example, to create and drop tables you can add the following line to your application.properties:

   spring.jpa.hibernate.ddl-auto=create-drop
   

   为此，Hibernate自己的内部属性名称是hibernate.hbm2ddl.auto(如果您还记得的话).

   Hibernate’s own internal property name for this (if you happen to remember it better) is hibernate.hbm2ddl.auto.

   1. 从此链接

   spring.jpa.hibernate.ddl-auto这实际上是"hibernate.hbm2ddl.auto"属性的快捷方式.

   spring.jpa.hibernate.ddl-auto This is actually a shortcut for the "hibernate.hbm2ddl.auto" property.

   使用嵌入式数据库且未检测到任何模式管理器时，默认为"create-drop".否则，默认为"none".

   Defaults to "create-drop" when using an embedded database and no schema manager was detected. Otherwise, defaults to "none".

   1. 从此

      • Spring Boot可以自动创建数据源的架构(DDL脚本)并对其进行初始化(DML脚本).

        • Spring Boot can automatically create the schema (DDL scripts) of your DataSource and initialize it (DML scripts).

          它从标准根类路径位置(分别为schema.sql和data.sql)加载SQL.

          It loads SQL from the standard root classpath locations: schema.sql and data.sql, respectively.

          此外，Spring Boot处理schema-${platform}.sql和data-${platform}.sql文件(如果存在)，其中platform是spring.datasource.platform的值.

          In addition, Spring Boot processes the schema-${platform}.sql and data-${platform}.sql files (if present), where platform is the value of spring.datasource.platform.

          这使您可以在必要时切换到特定于数据库的脚本.例如，您可以选择将其设置为数据库的供应商名称(hsqldb，h2，oracle，mysql，postgresql等).

          This allows you to switch to database-specific scripts if necessary. For example, you might choose to set it to the vendor name of the database (hsqldb, h2, oracle, mysql, postgresql, and so on).

          这篇关于spring.jpa.hibernate.hbm2ddl和spring.jpa.hibernate.ddl之间的区别的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！