Spring Boot Connecting to 2 Different Data Sources Using application.properties or application.yaml File

Question

My application using Spring JPA and it should connect to 2 different data sources. One to connect to DB2, the other to connect to Oracle.

I have set my application properties like below:

# DB2 DATA SOURCE
# ==============================
spring.datasource.url=jdbc:db2://server:port/database:currentSchema=schema-name;
spring.datasource.username=user1
spring.datasource.password=password1
spring.datasource.driver-class-name=com.ibm.db2.jcc.DB2Driver

# ORACLE DATA SOURCE
# ==============================
oracle.datasource.url=jdbc:oracle:thin:@server:port/database
oracle.datasource.username=user2
oracle.datasource.password=password2

# ==============================
# = JPA / HIBERNATE
# ==============================
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

# **How to specify the dialects hibernate needs to use in this scenario?**
#spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.DB2390Dialect
#spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.Oracle10gDialect

Above, my DB2 is working fine but as soon as I add 2nd data source (for Oracle), I am getting

java.lang.IllegalStateException: Failed to load ApplicationContext Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path ... Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set

Answer 1

Setting properties in application.yml or application.properties don't automatically create DB connections. When using multiple databases you have to configure them manually.

In your case, Spring configures db2 because of spring.datasource.* properties and ignores Oracle DB as it treats them as custom properties. To fix this, you have create separate configuration classes that defines

1. Data Source
2. Transaction Manager
3. Entity Manager Factory

Spring Data team created an example for this.

1. Customer DB
2. Order DB