Question:
Here I am trying to achieve the below in AWS RDS. I have a MySQL database instance running. I am thinking of creating a read replica so that I will have some extra load sharing capabilities.
I have a Spring Boot application running on EC2. Currently the way I connect to the database is by adding the below properties in the application.yml:
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datasource: type: com.zaxxer.hikari.HikariDataSource url: jdbc:mysql://DB_HOSTNAME:3306/DB_DATABASE?useUnicode=true&characterEncoding=utf8&useSSL=false&useLegacyDatetimeCode=false&serverTimezone=UTC username: DB_USERNAME password: DB_PASSWORD |
My question is:
- If I create a read replica, do I need to write some special code to connect to it?
- Do I need multiple connection pools one for each instance of the database?
- How is this scalable from code perspective, if I have 5 read replicas, how do I manage this in code?
- How do I direct my database calls to different replicas? What is the basis of this decision?
If there is any link/video/documentation you can point me to. Spring boot is not a necessity, I need to understand what is a good way to utilize my read replicas from a Java application.
Thanks
Answer:
If we use spring-cloud-aws-jdbc
Then
Point 1
How to connect to Main and read replica instances
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cloud.aws.rds. cloud.aws.rds. cloud.aws.rds. cloud.aws.rds.employee-db.readReplicaSupport=true |
Point 2
No Need to define a separate connection pool
Point 3
Spring Cloud AWS will search for any read-replica that is created for the master database and route the read-only transactions to one of the read-replicas that are available.
Point 4
You can redirect read transactions by
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@Transactional(readOnly = true) |
You can find a working example and details explanation here