Create a Spanner Instance with a Specific Number of Nodes
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. A key principle to apply: gcloud spanner instances create. 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-west1 \
--description="Test Instance" \
--nodes=2 \
--processing-units=1000
```
The command output shows an error: "ERROR: (gcloud.spanner.instances.create) INVALID_ARGUMENT: processing_units and nodes cannot be set simultaneously."
What is the correct way to create a Spanner instance with 2 nodes?
Exhibit
Refer to the exhibit.
```
gcloud spanner instances create test-instance \
--config=regional-us-west1 \
--description="Test Instance" \
--nodes=2 \
--processing-units=1000
```
The command output shows an error: "ERROR: (gcloud.spanner.instances.create) INVALID_ARGUMENT: processing_units and nodes cannot be set simultaneously."
A
Use --num-nodes=2 instead of --nodes
Why wrong: --nodes is correct flag; --num-nodes does not exist.
B
Set --processing-units=2000 and remove --nodes
Why wrong: That creates an instance with 2000 processing units, not 2 nodes.
C
Remove the --processing-units flag
Nodes and processing units are exclusive; remove one.
D
Set --nodes=2 and --processing-units=0
Why wrong: They cannot be set simultaneously regardless of value.
The answer is to remove the `--processing-units` flag and use `--num-nodes=2` when creating the instance. This is correct because Google Cloud Spanner enforces a strict separation between node-based and processing-unit-based configurations: `--num-nodes` provisions dedicated compute and storage capacity for production workloads, while `--processing-units` is designed for smaller, burstable configurations ranging from 100 to 1000 processing units per node equivalent, and the two flags cannot be combined in the same command. On the Google Professional Cloud Database Engineer exam, this question tests your understanding of Spanner instance provisioning and the distinction between fixed node counts and flexible processing units—a common trap is assuming you can specify both flags or that `--processing-units` can scale to full node capacity. Remember the memory tip: "Nodes are for production, processing units are for prototyping—never mix the two flags."
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
✓
Remove the --processing-units flag
Option C is correct because `--processing-units` and `--nodes` are mutually exclusive flags in `gcloud spanner instances create`. To create a 2-node instance, you must use only `--nodes=2` and omit `--processing-units`. The `--nodes` flag is the correct way to specify the number of nodes; `--num-nodes` is not a valid flag.
Key principle: gcloud spanner instances create
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 --num-nodes=2 instead of --nodes
Why it's wrong here
--nodes is correct flag; --num-nodes does not exist.
✗
Set --processing-units=2000 and remove --nodes
Why it's wrong here
That creates an instance with 2000 processing units, not 2 nodes.
✓
Remove the --processing-units flag
Why this is correct
Nodes and processing units are exclusive; remove one.
Related concept
gcloud spanner instances create
✗
Set --nodes=2 and --processing-units=0
Why it's wrong here
They cannot be set simultaneously regardless of value.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap is that candidates may think they need to use both `--nodes` and `--processing-units` or that `--processing-units` can be used for any instance size. In reality, `--processing-units` is only for small, burstable configurations (up to 1000 processing units), and for node-based instances, only `--nodes` is used. They are mutually exclusive.
Detailed technical explanation
How to think about this question
Google Cloud Spanner instances are provisioned with either `--num-nodes` (for dedicated capacity, each node provides 2 TB of storage and up to 10,000 QPS) or `--processing-units` (for burstable capacity, where 1000 processing units equals 1 node). The two flags cannot be used together; attempting to do so results in a validation error. In production, using `--num-nodes` is preferred for predictable performance and larger storage needs, while `--processing-units` is suitable for development or variable workloads.
KKey Concepts to Remember
gcloud spanner instances create
--nodes flag
--processing-units flag
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
gcloud spanner instances create
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. gcloud spanner instances create Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review gcloud spanner instances create, then practise related PCDE questions on the same topic to reinforce the concept.
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — gcloud spanner instances create.
What is the correct answer to this question?
The correct answer is: Remove the --processing-units flag — Option C is correct because `--processing-units` and `--nodes` are mutually exclusive flags in `gcloud spanner instances create`. To create a 2-node instance, you must use only `--nodes=2` and omit `--processing-units`. The `--nodes` flag is the correct way to specify the number of nodes; `--num-nodes` is not a valid flag.
What should I do if I get this PCDE question wrong?
Review gcloud spanner instances create, then practise related PCDE questions on the same topic to reinforce the concept.
What is the key concept behind this question?
gcloud spanner instances create
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