PCDE Practice Question: Manage a solution that can span multiple database technologies
You need to set up disaster recovery for a Cloud SQL for PostgreSQL instance. The primary instance is in us-central1, and you want a standby in us-west1 that can be promoted to a standalone instance during a regional outage. The solution must minimize data loss and recovery time. Which approach should you take?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a cross-region read replica in us-west1. During a disaster, promote the replica to a standalone instance.
Cross-region read replicas in Cloud SQL for PostgreSQL use synchronous replication (for regional replicas, it's asynchronous across regions, but still the best option for DR). Creating a cross-region read replica in us-west1 allows it to be promoted to a standalone instance in DR scenarios. Cross-region backups are point-in-time backups, not a live standby. External replication is not managed by Cloud SQL.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure cross-region automated backups with a retention of 7 days. In the event of a disaster, restore the latest backup to a new instance in us-west1.
Why it's wrong here
Backups have higher RPO and RTO compared to a live replica. This is less optimal than a cross-region replica.
- ✗
Set up an on-premise PostgreSQL instance and configure streaming replication from Cloud SQL to the on-premise instance.
Why it's wrong here
This requires external connectivity and is not a fully managed solution within GCP.
- ✓
Create a cross-region read replica in us-west1. During a disaster, promote the replica to a standalone instance.
Why this is correct
A cross-region read replica is the best option: it stays up-to-date (asynchronously) and can be promoted quickly.
- ✗
Use gcloud sql instances create with a backup configuration pointing to us-west1, but this does not create a live standby.
Why it's wrong here
This is invalid; backup configuration is not an instance.
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Variation 1. You need to create a read replica of a Cloud SQL for PostgreSQL instance in a different region for disaster recovery. What must be true about the primary instance to support cross-region replicas?
easy- A.The primary instance must have point-in-time recovery disabled.
- B.The primary instance must be using a regional (high-availability) configuration.
- C.The primary instance must have the 'cloudsql.logical_decoding' flag set to 'off'.
- ✓ D.The primary instance must have automated backups enabled.
Why D: Cross-region read replicas for Cloud SQL for PostgreSQL require automated backups to be enabled on the primary instance. Automated backups are necessary to maintain the WAL (Write-Ahead Log) archive, which is used for replication. The primary does not need to be regional; a zonal (non-HA) instance can also support cross-region replicas. Point-in-time recovery is automatically enabled when automated backups are on, and the flag 'cloudsql.logical_decoding' must be set to 'on' (not 'off') for PostgreSQL replication.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCDE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCDE exam.