The answer is to use single-cluster routing with single-row transactions. This configuration is necessary because Cloud Bigtable’s replication across clusters is eventually consistent by design, meaning it cannot guarantee strong consistency for reads after writes when multiple clusters are involved. By routing all operations for a given row to a single cluster and using single-row transactions, you enforce ACID semantics at the row level, ensuring that every read reflects the most recent write. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of the trade-off between replication and consistency—a common trap is assuming that replication automatically provides strong consistency, when in fact it sacrifices it for availability. Remember the memory tip: “One row, one cluster, one truth” to recall that strong consistency in Bigtable requires confining reads and writes to a single cluster.
PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 uses Cloud Bigtable with replication across two clusters in us-east1 and us-west1. They have a critical application that requires strong consistency for all reads after writes. What configuration should they implement to meet this requirement?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use single-cluster routing with single-row transactions.
Cloud Bigtable does not support strong consistency across clusters in a replicated setup; replication is eventually consistent. To guarantee strong consistency for reads after writes, you must use single-cluster routing with single-row transactions, which ensures that all reads and writes for a given row are processed by the same cluster, providing ACID semantics for that row.
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 cluster-group routing with multi-cluster routing.
Why it's wrong here
Cluster-group routing does not exist; multi-cluster routing is eventual consistency.
✓
Use single-cluster routing with single-row transactions.
Why this is correct
Single-cluster routing ensures all reads and writes go to the same cluster, providing strong consistency.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable inter-cluster replication with strong consistency.
Why it's wrong here
Inter-cluster replication is eventual consistency.
✗
Use multi-cluster routing to automatically route to the nearest cluster.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume 'replication' implies strong consistency, but Cloud Bigtable's cross-cluster replication is eventually consistent, and the only way to achieve strong consistency is to confine all operations to a single cluster using single-row transactions.
Detailed technical explanation
How to think about this question
Cloud Bigtable uses a distributed storage system based on Google's Chubby lock service and Bigtable architecture. Single-cluster routing with single-row transactions leverages the fact that all replicas of a row are stored in the same tablet server within a cluster, allowing atomic reads and writes. In contrast, cross-cluster replication relies on asynchronous replication logs, meaning a write committed in us-east1 may take seconds to propagate to us-west1, making strong consistency impossible without single-cluster routing.
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
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
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: Use single-cluster routing with single-row transactions. — Cloud Bigtable does not support strong consistency across clusters in a replicated setup; replication is eventually consistent. To guarantee strong consistency for reads after writes, you must use single-cluster routing with single-row transactions, which ensures that all reads and writes for a given row are processed by the same cluster, providing ACID semantics for that row.
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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