Using Multiple EntityManagerFactories

If you need to use JPA against multiple data sources, you likely need one EntityManagerFactory per data source. The LocalContainerEntityManagerFactoryBean from Spring ORM allows you to configure an EntityManagerFactory for your needs. You can also reuse JpaProperties to bind settings for each EntityManagerFactory, as shown in the following example:

Java
Kotlin

import javax.sql.DataSource;

import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;

@Configuration(proxyBeanMethods = false)
public class MyEntityManagerFactoryConfiguration {

	@Bean
	@ConfigurationProperties("app.jpa.first")
	public JpaProperties firstJpaProperties() {
		return new JpaProperties();
	}

	@Bean
	public LocalContainerEntityManagerFactoryBean firstEntityManagerFactory(DataSource firstDataSource,
			JpaProperties firstJpaProperties) {
		EntityManagerFactoryBuilder builder = createEntityManagerFactoryBuilder(firstJpaProperties);
		return builder.dataSource(firstDataSource).packages(Order.class).persistenceUnit("firstDs").build();
	}

	private EntityManagerFactoryBuilder createEntityManagerFactoryBuilder(JpaProperties jpaProperties) {
		JpaVendorAdapter jpaVendorAdapter = createJpaVendorAdapter(jpaProperties);
		return new EntityManagerFactoryBuilder(jpaVendorAdapter, jpaProperties.getProperties(), null);
	}

	private JpaVendorAdapter createJpaVendorAdapter(JpaProperties jpaProperties) {
		// ... map JPA properties as needed
		return new HibernateJpaVendorAdapter();
	}

}

import javax.sql.DataSource

import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties
import org.springframework.boot.context.properties.ConfigurationProperties
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.orm.jpa.JpaVendorAdapter
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter

@Configuration(proxyBeanMethods = false)
class MyEntityManagerFactoryConfiguration {

	@Bean
	@ConfigurationProperties("app.jpa.first")
	fun firstJpaProperties(): JpaProperties {
		return JpaProperties()
	}

	@Bean
	fun firstEntityManagerFactory(
		firstDataSource: DataSource?,
		firstJpaProperties: JpaProperties
	): LocalContainerEntityManagerFactoryBean {
		val builder = createEntityManagerFactoryBuilder(firstJpaProperties)
		return builder.dataSource(firstDataSource).packages(Order::class.java).persistenceUnit("firstDs").build()
	}

	private fun createEntityManagerFactoryBuilder(jpaProperties: JpaProperties): EntityManagerFactoryBuilder {
		val jpaVendorAdapter = createJpaVendorAdapter(jpaProperties)
		return EntityManagerFactoryBuilder(jpaVendorAdapter, jpaProperties.properties, null)
	}

	private fun createJpaVendorAdapter(jpaProperties: JpaProperties): JpaVendorAdapter {
		// ... map JPA properties as needed
		return HibernateJpaVendorAdapter()
	}

}

The example above creates an EntityManagerFactory using a DataSource bean named firstDataSource. It scans entities located in the same package as Order. It is possible to map additional JPA properties using the app.first.jpa namespace.

When you create a bean for LocalContainerEntityManagerFactoryBean yourself, any customization that was applied during the creation of the auto-configured LocalContainerEntityManagerFactoryBean is lost. For example, in case of Hibernate, any properties under the spring.jpa.hibernate prefix will not be automatically applied to your LocalContainerEntityManagerFactoryBean. If you were relying on these properties for configuring things like the naming strategy or the DDL mode, you will need to explicitly configure that when creating the LocalContainerEntityManagerFactoryBean bean.

You should provide a similar configuration for any additional data sources for which you need JPA access. To complete the picture, you need to configure a JpaTransactionManager for each EntityManagerFactory as well. Alternatively, you might be able to use a JTA transaction manager that spans both.

If you use Spring Data, you need to configure @EnableJpaRepositories accordingly, as shown in the following examples:

Java
Kotlin

import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = Order.class, entityManagerFactoryRef = "firstEntityManagerFactory")
public class OrderConfiguration {

}

import org.springframework.context.annotation.Configuration
import org.springframework.data.jpa.repository.config.EnableJpaRepositories

@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = [Order::class], entityManagerFactoryRef = "firstEntityManagerFactory")
class OrderConfiguration

Java
Kotlin

import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = Customer.class, entityManagerFactoryRef = "secondEntityManagerFactory")
public class CustomerConfiguration {

}

import org.springframework.context.annotation.Configuration
import org.springframework.data.jpa.repository.config.EnableJpaRepositories

@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = [Customer::class], entityManagerFactoryRef = "secondEntityManagerFactory")
class CustomerConfiguration