Exam Professional Data Engineer topic 1 question 218 discussion

After promoting the read replica in Region2 to be the new primary instance, creating additional read replicas from it can help distribute the read load and maintain or increase the database's total capacity.

Corrected answer: C If the primary instance (db-a-0) becomes unavailable, you can promote the replica in region B to become the primary. To again have additional replicas in regions A and C, delete the old instances (the former primary instance in A, and the replica in C), and create new read replicas from the new primary instance in B.

Question is flawed but the closest answer would be D since C will result in 2 read replicas on Region 3 (original one and new now) Option C- Create two new read replicas from the new primary instance - contradicts with the requirements - You need to ensure that your application has the same database capacity available 'before you switch over the connections.' Option D- Create a new read replica in Region1, promote the new read replica to be the primary instance - contradicts with the requirement - 'requires that you perform disaster recovery by promoting a read replica in Region2.' How does this affect the answer choices?

https://cloud.google.com/sql/docs/mysql/replication#cross-region-read-replicas

The best option here is C. Create two new read replicas from the new primary instance, one in Region3 and one in a new region. Here's the breakdown: Capacity Restoration: Promoting the Region2 replica makes it the new primary. You need to replicate from this new primary to maintain redundancy and capacity. Creating two replicas (Region3, new region) accomplishes this. Geographic Distribution: Distributing replicas across regions ensures availability if another regional event occurs. Speed: Creating new replicas from the promoted primary is likely faster than promoting another existing replica.

Option C

Immediate Failover: Promoting the read replica in Region2 quickly restores database operations in a different region, aligning with disaster recovery goals. Capacity Restoration: Creates two new read replicas from the promoted primary instance (formerly the read replica in Region2). This replaces the lost capacity in Region1 and adds a read replica in a new region for further redundancy.