PROFESSIONAL-DATA-ENGINEER Question #318: Real Exam Question with Answer & Explanation

Question

You are deploying a MySQL database workload onto Cloud SQL. The database must be able to scale up to support several readers from various geographic regions. The database must be highly available and meet low RTO and RPO requirements, even in the event of a regional outage. You need to ensure that interruptions to the readers are minimal during a database failover. What should you do?

Options

• ACreate a highly available Cloud SQL instance in region Create a highly available read replica in region B. Scale up read workloads by creating cascading read
• BCreate a highly available Cloud SQL instance in region A. Scale up read workloads by creating read replicas in multiple regions. Promote one of the read
• CCreate a highly available Cloud SQL instance in region A. Create a highly available read replica in region B. Scale up read workloads by creating cascading
• DCreate a highly available Cloud SQL instance in region A. Scale up read workloads by creating read replicas in the same region. Failover to the standby Cloud

Explanation

Option A is correct because it combines an HA primary in region A with an HA cross-region read replica in region B, plus cascading read replicas off that regional replica. This architecture means readers in region B are already served locally - if region A suffers an outage, the HA replica in region B promotes automatically with minimal interruption to connected readers, satisfying both low RTO/RPO and cross-regional scale requirements.

Option B is wrong because promoting a read replica to primary during a failover is a manual, disruptive process - it breaks existing reader connections and doesn't meet "minimal interruption" requirements.

Option C is a near-miss but lacks making the cross-region replica itself highly available; without HA on the region B replica, a zonal failure there would still leave readers without a standby.

Option D fails the geographic distribution requirement entirely - same-region replicas cannot survive a regional outage, and failing over to a standby in the same downed region provides no real disaster recovery.

Memory tip: Think "HA all the way down" - HA primary → HA cross-region replica → cascading replicas. Each layer adds both redundancy and read scale, and since readers never leave region B, a region A outage becomes nearly invisible to them.

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