Spring boot Hibernate error "Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set" when working with multiple data sources - oracle

Question

I am building a Springboot application that needs to talk to 2 different databases (DB2 and Oracle).
Spring-boot-starter-parent version 2.6.6
hibernate version 5.6.7.Final
I first added DB2 support and that was working fine until I added oracle related settings in application.properties file below.
Adding oracle related settings causes following error:
org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
Below are the databases and hibernate related settings from my application.properties:
# ==============================
# = DB2
db2.datasource.jdbc-url=jdbc:db2://SERVER1:PORT/DATABASE-1:currentSchema=SCHEMA;
db2.datasource.username=USER1
db2.datasource.password=PASSWORD1
db2.datasource.driver-class-name=com.ibm.db2.jcc.DB2Driver
db2.jpa.properties.hibernate.dialect=org.hibernate.dialect.DB2390Dialect
# ==============================
# = ORACLE
oracle.datasource.jdbc-url=jdbc:oracle:thin:#SERVER2:PORT/DATABASE-2
oracle.datasource.username=USER2
oracle.datasource.password=PASSWORD2
oracle.jpa.properties.hibernate.dialect=org.hibernate.dialect.Oracle10gDialect
# ==============================
# = JPA / HIBERNATE
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
My pom.xml contains dependencies for oracle and DB2 amongs other required dependencies:
...
<dependency>
<groupId>com.ibm.db2</groupId>
<artifactId>jcc</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.oracle.database.jdbc</groupId>
<artifactId>ojdbc8</artifactId>
<scope>runtime</scope>
</dependency>
...
I have placed my entities, repositories, and data source configurations into different packages as I read is required in this article https://www.javadevjournal.com/spring-boot/multiple-data-sources-with-spring-boot/. My package structure looks like:
project
- dataconfig
- db2
- config
- entity
- repository
- oracle
- config
- entity
- repository
I also added some entities and repositories and my configuration classes.
Here is my DB2Configuration class:
package project.dataconfig.db2.config;
#Configuration
#EnableTransactionManagement
#EnableJpaRepositories(
entityManagerFactoryRef = "db2EntityManagerFactory",
transactionManagerRef = "db2TransactionManager",
basePackages = {
"project.dataconfig.db2.repository"
}
)
public class Db2Configuration {
#Primary
#Bean(name = "db2DataSource")
#ConfigurationProperties(prefix = "db2.datasource")
public DataSource db2DataSource() {
return DataSourceBuilder.create().build();
}
#Primary
#Bean(name = "db2EntityManagerFactory")
public LocalContainerEntityManagerFactoryBean entityManagerFactory(
EntityManagerFactoryBuilder builder
, #Qualifier("db2DataSource") DataSource dataSource) {
return builder
.dataSource(dataSource)
.packages("project.dataconfig.db2.entity")
.persistenceUnit("db2persistanceunit")
.build();
}
#Primary
#Bean(name = "db2TransactionManager")
public PlatformTransactionManager db2TransactionManager(
#Qualifier("db2EntityManagerFactory") EntityManagerFactory db2EntityManagerFactory) {
return new JpaTransactionManager(db2EntityManagerFactory);
}
}
Here is my OracleConfiguration class:
package project.dataconfig.oracle.config;
#Configuration
#EnableTransactionManagement
#EnableJpaRepositories(
entityManagerFactoryRef = "oracleEntityManagerFactory",
transactionManagerRef = "oracleTransactionManager",
basePackages = {
"project.dataconfig.oracle.repository"
}
)
public class OracleConfiguration {
#Bean(name = "oracleDataSource")
#ConfigurationProperties(prefix = "oracle.datasource")
public DataSource oracleDataSource() {
return DataSourceBuilder.create().build();
}
#Bean(name = "oracleEntityManagerFactory")
public LocalContainerEntityManagerFactoryBean entityManagerFactory(
EntityManagerFactoryBuilder builder
, #Qualifier("oracleDataSource") DataSource dataSource) {
return builder
.dataSource(dataSource)
.packages("project.dataconfig.oracle.entity")
.persistenceUnit("oraclepersistanceunit")
.build();
}
#Bean(name = "oracleTransactionManager")
public PlatformTransactionManager oracleTransactionManager(
#Qualifier("oracleEntityManagerFactory") EntityManagerFactory oracleEntityManagerFactory) {
return new JpaTransactionManager(oracleEntityManagerFactory);
}
}
Before I added oracle related settings in application.properties file, my application worked just find with only DB2 settings as described above.
Once I added oracle related settings and configuration, I started getting this error:
org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
Based on the error, I think the problem is caused by my settings for Hibernate dialect in application.properties file. I think it is caused by one of the two settings
...
db2.jpa.properties.hibernate.dialect=org.hibernate.dialect.DB2390Dialect
...
oracle.jpa.properties.hibernate.dialect=org.hibernate.dialect.Oracle10gDialect
How do I resolve this issue?

Answer 1

I figure it out.
Modify method entityManagerFactory for both Db2Configuration and OracleConfiguration to supply them with the information about hibernate dialect:
for DB2
#Primary
#Bean(name = "db2EntityManagerFactory")
public LocalContainerEntityManagerFactoryBean entityManagerFactory(
EntityManagerFactoryBuilder builder
, #Qualifier("db2DataSource") DataSource dataSource) {
final HashMap<String, Object> hibernateProperties = new HashMap<String, Object>();
hibernateProperties.put("hibernate.dialect", "org.hibernate.dialect.DB2390Dialect");
return builder
.dataSource(dataSource)
.packages("project.dataconfig.db2.entity")
.properties(hibernateProperties)
.persistenceUnit("db2persistanceunit")
.build();
}
for Oracle
#Bean(name = "oracleEntityManagerFactory")
public LocalContainerEntityManagerFactoryBean entityManagerFactory(
EntityManagerFactoryBuilder builder
, #Qualifier("oracleDataSource") DataSource dataSource) {
final HashMap<String, Object> hibernateProperties = new HashMap<String, Object>();
hibernateProperties.put("hibernate.dialect", "org.hibernate.dialect.Oracle10gDialect");
return builder
.dataSource(dataSource)
.packages("project.dataconfig.oracle.entity")
.properties(hibernateProperties)
.persistenceUnit("oraclepersistanceunit")
.build();
}
After this, my console shows when running app, indicating all is good:
HHH000400: Using dialect: org.hibernate.dialect.DB2390Dialect
Initialized JPA EntityManagerFactory for persistence unit 'db2persistanceunit'
HHH000204: Processing PersistenceUnitInfo [name: oraclepersistanceunit]
HHH000400: Using dialect: org.hibernate.dialect.Oracle10gDialect
Initialized JPA EntityManagerFactory for persistence unit 'oraclepersistanceunit'
My actuator /health endpoint also sees both databases as up and running.