Google PCA Practice Question: Analyze and optimize technical and business processes
A retail company runs a legacy order-processing system on a single Compute Engine VM with a local SSD. The system is business-critical and must be migrated to Google Cloud with minimal downtime and no data loss. The database is PostgreSQL, and the company wants to move to a managed service. The cutover window is only 30 minutes. Which migration approach should the architect recommend?
⚠ Common exam trap
The trap here is assuming that a cold backup and restore or a lift-and-shift can meet a 30-minute cutover with no data loss, when continuous replication is required for minimal downtime.
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
✓
Use Database Migration Service to perform a continuous replication from the source PostgreSQL to Cloud SQL for PostgreSQL, then promote during the cutover window.
Database Migration Service provides continuous replication from a self-managed PostgreSQL source to Cloud SQL, enabling a short cutover window with minimal downtime and no data loss. The other options either require significant downtime, are unsupported, or do not result in a managed service. For a business-critical system with a tight cutover window, continuous replication is the recommended approach.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Take a cold backup of the PostgreSQL database, transfer it to Cloud Storage, and restore it to a new Cloud SQL instance during the cutover window.
Why it's wrong here
A cold backup requires stopping the source database, which causes downtime beyond the 30-minute window. Transferring and restoring a large database also takes time and may not complete within the window. This approach risks data loss if any transactions occur after the backup, and it does not meet the minimal downtime requirement.
- ✓
Use Database Migration Service to perform a continuous replication from the source PostgreSQL to Cloud SQL for PostgreSQL, then promote during the cutover window.
Why this is correct
Database Migration Service supports continuous replication from a self-managed PostgreSQL source to Cloud SQL, keeping the target in sync until cutover. This minimizes downtime because only the final promotion and connection switch are needed during the 30-minute window. It also avoids data loss by replicating ongoing changes, making it the best fit for the requirements.
- ✗
Lift and shift the VM to a Compute Engine instance with a persistent disk, then convert it to a Cloud SQL instance later.
Why it's wrong here
Lifting and shifting the VM does not move to a managed service and does not address the requirement for minimal downtime. Converting to Cloud SQL later would require another migration with its own downtime. This approach adds complexity and does not leverage managed services, so it fails to meet the stated goals.
- ✗
Create a Cloud SQL read replica from the on-premises PostgreSQL using native replication, then promote the replica during cutover.
Why it's wrong here
Cloud SQL does not support creating a read replica directly from an external PostgreSQL instance. Native replication to an external replica is possible, but Cloud SQL requires the source to be accessible and may not support all replication topologies. This approach is not a supported managed migration path and would require significant manual setup, increasing risk.
Go deeper
Related to this question
Learn chapter
Google Kubernetes Engine (GKE)
Key term
Cloud SQL
Cloud SQL is a fully managed relational database service that lets you set up, maintain, and scale SQL databases (like MySQL, PostgreSQL, and SQL Server) in the cloud without managing the underlying infrastructure.
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
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