The answer is to create a read replica running MySQL 8.0 and then promote it to become the new primary. This strategy minimizes downtime because the replica stays continuously synchronized with the source instance through MySQL’s native replication, so when you promote it, only a brief replication lag needs to catch up—typically seconds—rather than hours needed for an export and import of a 500 GB database. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of Cloud SQL’s replication capabilities and the trade-offs between data volume and downtime; a common trap is choosing the slower dump-and-restore method or assuming an in-place upgrade is viable for major versions without extended read-only periods. Remember the key insight: replication keeps the data warm, so promotion is nearly instant. Memory tip: “Replicate, then promote—don’t export, don’t demote.”
PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a Cloud SQL instance with a 500 GB database. They need to perform a major version upgrade from MySQL 5.7 to 8.0 with minimal downtime. Which strategy should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a read replica with new version, then promote
Creating a read replica with the new MySQL version and then promoting it minimizes downtime because replication keeps the replica synchronized with the primary until promotion. This approach avoids the lengthy export/import process and reduces the risk of data loss or extended unavailability.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Create a read replica with new version, then promote
Why this is correct
A read replica can be created with MySQL 8.0 and promoted after sync, minimizing downtime to a failover moment.
Related concept
Read the scenario before looking for a memorised answer.
✗
Export and import the database
Why it's wrong here
Export/import causes significant downtime and is error-prone for large databases.
✗
Use in-place upgrade via gcloud command
Why it's wrong here
In-place upgrade requires a period of downtime and may fail.
✗
Upgrade during maintenance window
Why it's wrong here
A maintenance window still incurs downtime, though planned.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think an in-place upgrade (Option C) is possible with a simple gcloud command, but Cloud SQL requires a replica-based approach for major version changes to ensure minimal downtime and data integrity.
Detailed technical explanation
How to think about this question
Cloud SQL read replicas use asynchronous replication based on MySQL's binary log (binlog) position or GTID. When promoting a replica, the replication stops, and the replica becomes a standalone instance with the new version, typically completing in seconds. This strategy is ideal for major version upgrades because it allows the primary to serve traffic uninterrupted until the cutover.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a read replica with new version, then promote — Creating a read replica with the new MySQL version and then promoting it minimizes downtime because replication keeps the replica synchronized with the primary until promotion. This approach avoids the lengthy export/import process and reduces the risk of data loss or extended unavailability.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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