DB Subnet Group
- DB Subnet group specifies in which subnets (AZ’s) your db instances have to be created
- AWS by default creates a db subnet group called as default
- Lets try to create our own db subnet group. Each DB Subnet group shoult have atleast two AZ’s
- Selecting subnet group while create db instance
Read Replica
- A read replica is a read-only copy of your master db instance i.e. kept in sync with your master databases.
- You can have 15 read replicas in RDS (depending on your RDBMS engine)
- A read replica helps you offload the read-only queries to it, there by reducing the workload to the master databases.
- Benefits
- You can offload read-only traffic to the read replica and let the master database run the critical transaction related queries
- If you have users from different locations, you can create read replica in different region
- The read-replica can also be promoted to a master database when master goes down.
Scenario: Read Replica Setup
- Create an rds db instance with mysql engine of size db.t2.micro
- Ensure the region is ap-south-1 (mumbai)
- The AZ’s for creating db should be ap-south-1a and ap-south-1b
- Create a read replica in mumbai region
- Create a read replica in any other region (us-west-2):
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In the same way create a read replica by selecting the region us-west-2
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Follow the classroom video for the queries executed.
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