Seems JPA spring.jpa.hibernate.ddl-auto=update doesn’t work

I build a simple SpringBoot App (version: 2.4.3). I have the following Entity:

package com.ksteindl.logolo.domain;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Foo {

    @Id
    private String id;
    private String foo;

    public String getFoo() {
        return foo;
    }

    public void setFoo(String foo) {
        this.foo = foo;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getId() {
        return id;
    }
}

and an application.properties

spring.jpa.show-sql=true

spring.datasource.url = jdbc:mysql://localhost:3306/mysql
spring.datasource.username=admin
spring.datasource.password=admin

spring.jpa.database-platform=org.hibernate.dialect.MySQL5Dialect

spring.jpa.hibernate.ddl-auto=update

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL57Dialect

At first run, everything seems fine. The tables are created according to the Entites. However, when I restart my app, I get exceptions for every Entity/Table I have. Moreover, if I modify my Entity (for example introduce a bar attribute in Foo Entity), the corresponding Table didn’t change in the DB. It seems to me, that it tries to re-create the tables, but I don’t know why. I got the following Exceptions for every Table/Entity I have:

Hibernate: create table foo (id varchar(255) not null, bar varchar(255), baz varchar(255), foo varchar(255), primary key (id)) engine=InnoDB
2021-04-02 16:34:17.000  WARN 16359 --- [  restartedMain] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "create table foo (id varchar(255) not null, bar varchar(255), baz varchar(255), foo varchar(255), primary key (id)) engine=InnoDB" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "create table foo (id varchar(255) not null, bar varchar(255), baz varchar(255), foo varchar(255), primary key (id)) engine=InnoDB" via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:67) ~[hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.applySqlString(AbstractSchemaMigrator.java:559) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.applySqlStrings(AbstractSchemaMigrator.java:504) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.createTable(AbstractSchemaMigrator.java:277) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.internal.GroupedSchemaMigratorImpl.performTablesMigration(GroupedSchemaMigratorImpl.java:71) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.performMigration(AbstractSchemaMigrator.java:207) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.doMigration(AbstractSchemaMigrator.java:114) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:184) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:73) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:318) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:468) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1259) [hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) [spring-orm-5.3.4.jar:5.3.4]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.3.4.jar:5.3.4]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409) [spring-orm-5.3.4.jar:5.3.4]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396) [spring-orm-5.3.4.jar:5.3.4]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) [spring-orm-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1845) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1782) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:602) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) [spring-beans-5.3.4.jar:5.3.4]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1153) ~[spring-context-5.3.4.jar:5.3.4]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:907) ~[spring-context-5.3.4.jar:5.3.4]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:582) ~[spring-context-5.3.4.jar:5.3.4]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:767) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1311) ~[spring-boot-2.4.3.jar:2.4.3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1300) ~[spring-boot-2.4.3.jar:2.4.3]
    at com.ksteindl.logolo.LogoloApplication.main(LogoloApplication.java:10) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_282]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_282]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_282]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_282]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-2.4.3.jar:2.4.3]
Caused by: java.sql.SQLSyntaxErrorException: Table 'foo' already exists
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120) ~[mysql-connector-java-8.0.23.jar:8.0.23]
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.23.jar:8.0.23]
    at com.mysql.cj.jdbc.StatementImpl.executeInternal(StatementImpl.java:762) ~[mysql-connector-java-8.0.23.jar:8.0.23]
    at com.mysql.cj.jdbc.StatementImpl.execute(StatementImpl.java:646) ~[mysql-connector-java-8.0.23.jar:8.0.23]
    at com.zaxxer.hikari.pool.ProxyStatement.execute(ProxyStatement.java:95) ~[HikariCP-3.4.5.jar:na]
    at com.zaxxer.hikari.pool.HikariProxyStatement.execute(HikariProxyStatement.java) ~[HikariCP-3.4.5.jar:na]
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:54) ~[hibernate-core-5.4.28.Final.jar:5.4.28.Final]
    ... 40 common frames omitted

Can someone please help me? Thanks

Answer

In some cases, Hibernate is not able to make some changes on the database schema by itself.

That’s why in general we try not to set ddl-auto to update and we prefer to use a data migration tool like liquibase or flyway.

In very simple cases like adding a column for example, Hibernate will work very well because it’s a non breaking change. On the other hand, if you want to delete a column for example, it becomes more delicate. In this case your java entity will not know about this column anymore, but in the database it will still exist.

This is both a problem and a good thing because Hibernate makes sure that you don’t lose data, but it is also the reason why some changes are not made.

As I told you above, we will prefer to use data migration tools, which are made to do this kind of things.

You can have a look at Liquibase for example, which is a very good tool. Here are some useful links:

But you can also use flyway (which I don’t know) : https://flywaydb.org/

And finally, here is a comparison between Liquibase and Flyway rather interesting: https://dzone.com/articles/flyway-vs-liquibase