The answer is to run `gcloud spanner instances update test-instance --nodes=5` because Cloud Spanner supports live, online scaling without downtime. This command directly increases the node count, which raises the instance's compute capacity to handle higher traffic, and Spanner automatically redistributes data and processing across the new nodes while remaining fully available. On the Google Professional Cloud Database Engineer exam, this concept tests your understanding of Spanner’s elastic scaling model—a key differentiator from traditional databases that require maintenance windows for resizing. A common trap is assuming you must recreate the instance or use a separate provisioning tool, but Spanner’s architecture allows you to increase Cloud Spanner node count with a single update command. Memory tip: think “update, not recreate” for live scaling—Spanner nodes are like adding lanes to a highway while traffic keeps flowing.
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.
Exhibit
Refer to the exhibit.
```
gcloud spanner instances create test-instance \
--config=regional-us-central1 \
--description="Test Instance" \
--nodes=2
```
You run the above command to create a Spanner instance. Later, you need to increase the instance's compute capacity to handle higher traffic. What is the correct approach?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Run gcloud spanner instances update test-instance --nodes=5
Option D is correct because Cloud Spanner allows you to increase the compute capacity of an existing instance by updating the node count using the `gcloud spanner instances update` command. This operation is performed online without downtime, as Spanner supports live resizing of nodes to handle increased traffic.
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.
✗
Use the console to change the instance configuration to a larger one.
Why it's wrong here
Configuration cannot be changed after creation; only nodes can be scaled.
✗
Delete the instance and recreate with --nodes=5.
Why it's wrong here
Data loss and downtime.
✗
Create a new instance with a larger config and migrate data.
Why it's wrong here
Unnecessary; you can scale existing instance.
✓
Run gcloud spanner instances update test-instance --nodes=5
Why this is correct
This updates the node count without recreating the instance.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse changing the instance configuration (which requires migration) with scaling compute capacity by adjusting node count (which is a live, online operation).
Detailed technical explanation
How to think about this question
Cloud Spanner uses a shared-nothing architecture where each node provides a fixed amount of compute and storage capacity. Increasing the node count distributes the data and query load across more servers, improving throughput and reducing latency. The `gcloud spanner instances update` command triggers a live resizing process that rebalances data across the new nodes automatically, with no downtime or manual data migration required.
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: Run gcloud spanner instances update test-instance --nodes=5 — Option D is correct because Cloud Spanner allows you to increase the compute capacity of an existing instance by updating the node count using the `gcloud spanner instances update` command. This operation is performed online without downtime, as Spanner supports live resizing of nodes to handle increased traffic.
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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