java - Postgres Test Container - Why trying to drop constraint before drop table if exists cascade?

Question

I am using Postgres test container. If table has any constraint for example foreign key or unique hibernate is trying to drop this constraints first but after there is an error that realation doesn't exists - after this, warning "Hibernate: drop table if exists public.USERS cascade" is executed successfully and table is created and has added constraints. At the end constraints and tables are dropped successfully.

How to remove these warnings? Why is it trying to drop these constraints first or why it cannot do this (despite this that table doesn't exists)?

Test configuration:

spring:
  example:
    url: ${DB_URL}
    username: ${DB_USERNAME}
    password: ${DB_PASSWORD}
    vendor-overrides:
      hibernate.hbm2ddl.auto: create-drop
  example2:
    url: ${MYSQL_DB_URL}
    username: ${MYSQL_DB_USERNAME}
    password: ${MYSQL_DB_PASSWORD}
  jpa:
    properties:
      hibernate:
        default_schema: public
    show-sql: true
    hibernate:
      ddl-auto: create-drop

Database Configuration Class:

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = DatabaseMainConfig.REPO_NAME + "EntityManagerFactory",
        basePackages = {DatabaseMainConfig.REPO_PACKAGE}
)
@Primary
public class DatabaseMainConfig {

    public static final String REPO_NAME = "example";
    public static final String REPO_PACKAGE = "com.example.repositories.main";
    public static final String DATASOURCE_NAME = REPO_NAME + "Datasource";

    @Primary
    @Bean(name = REPO_NAME + "DatasourceProperties")
    @ConfigurationProperties("spring." + REPO_NAME)
    public DataSourceProperties basicDatasourceProperties() {
        return new DataSourceProperties();
    }

    @Primary
    @Bean(name = DATASOURCE_NAME)
    @ConfigurationProperties("spring." + REPO_NAME + ".configuration")
    public HikariDataSource dataSource() {
        return basicDatasourceProperties()
                .initializeDataSourceBuilder()
                .type(HikariDataSource.class)
                .build();
    }

    @Primary
    @Bean(name = REPO_NAME + "vendorOverrides")
    @ConfigurationProperties(prefix = "spring." + REPO_NAME + ".vendor-overrides")
    public Map<String, String> hibernateOverrideConfig() {
        return new HashMap<>();
    }

    @Primary
    @Bean(name = REPO_NAME + "EntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            EntityManagerFactoryBuilder entityManagerFactoryBuilder,
            @Qualifier(REPO_NAME + "Datasource") DataSource dataSource,
            @Qualifier(REPO_NAME + "vendorOverrides") Map<String, String> vendorProperties) {
        return entityManagerFactoryBuilder
                .dataSource(dataSource)
                .packages(REPO_PACKAGE, "org.springframework.data.jpa.convert.threeten")
                .properties(vendorProperties)
                .persistenceUnit(REPO_NAME)
                .build();
    }

    @Primary
    @Bean
    public PlatformTransactionManager transactionManager(
            @Qualifier(REPO_NAME + "EntityManagerFactory")
                    EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }

}

Test Container:

public class PostgresTestContainer extends PostgreSQLContainer<PostgresTestContainer> {

    private static final String IMAGE_VERSION = "postgres:11.1";
    private static final String DATABASE_NAME = "example";
    private static PostgresTestContainer container;

    public PostgresTestContainer() {
        super(IMAGE_VERSION);
    }

    public static PostgresTestContainer getInstance() {
        if (container == null) {
            container = new PostgresTestContainer().withDatabaseName(DATABASE_NAME);
        }
        return container;
    }

    @Override
    public void start() {
        super.start();
        System.setProperty("DB_URL", container.getJdbcUrl());
        System.setProperty("DB_USERNAME", container.getUsername());
        System.setProperty("DB_PASSWORD", container.getPassword());
    }

    @Override
    public void stop() {
        //do nothing, JVM handles shut down
    }
}

Hibernate: alter table public.USERS drop constraint FKls73pryys8w3n2h1ximbc390r
2021-01-25 15:33:11.426  WARN 79124 --- [    Test worker] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "alter table public.USERS drop constraint FKls73pryys8w3n2h1ximbc390r" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "alter table public.USERS drop constraint FKls73pryys8w3n2h1ximbc390r" via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:67) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.applySqlString(SchemaDropperImpl.java:375) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.applySqlStrings(SchemaDropperImpl.java:359) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.applyConstraintDropping(SchemaDropperImpl.java:331) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.dropFromMetadata(SchemaDropperImpl.java:230) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.performDrop(SchemaDropperImpl.java:154) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.doDrop(SchemaDropperImpl.java:126) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.doDrop(SchemaDropperImpl.java:112) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:145) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:73) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:316) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:469) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1259) [hibernate-core-5.4.17.Final.jar:5.4.17.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) [spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) [spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) [spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) [spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) [spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1109) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:120) ~[spring-boot-test-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99) ~[spring-test-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124) ~[spring-test-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:123) ~[spring-test-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:118) ~[spring-test-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83) ~[spring-test-5.2.7.RELEASE.jar:5.2.7.RE

Answer 1

Why is it trying to drop these constraints first or why it cannot do this (despite this that table doesn't exists)?

I think that happens because you configured the following:

hibernate:
      ddl-auto: create-drop

Regarding my knowledge create alone already drops existing tables and FK before creating new one so using create-drop will result in double drops (First one before creating tables, second one after spring context shuts down). As one drop already occurred before the second one the FK does not exists anymore.