The answer is to use stale reads, specifically through follower reads, which is one of the two correct strategies to reduce read latency in Cloud Spanner for globally distributed applications. This works because in a multi-region configuration, follower reads allow read requests to be served by any replica that is geographically closer to the client, rather than forcing a round trip to the leader replica. The second strategy is to use read-only transactions, which can also be directed to non-leader replicas. On the Google Professional Cloud Database Engineer exam, this topic tests your understanding of Spanner’s replication architecture and the trade-off between strong consistency and latency. A common trap is assuming all reads must go to the leader, but the exam emphasizes that relaxing consistency slightly with stale reads dramatically improves global performance. Memory tip: think “follow the follower” to remember that reads can be served by any replica, not just the leader.
PCDE Monitor and optimize database performance Practice Question
This PCDE practice question tests your understanding of monitor and optimize database performance. 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.
In Cloud Spanner, which TWO strategies can help reduce read latency for globally distributed applications?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable follower reads
Option A is correct because follower reads allow read requests to be served by any replica in a Cloud Spanner multi-region configuration, not just the leader replica. This reduces read latency by enabling reads to be processed from a replica that is geographically closer to the client, without incurring the round-trip time to the leader. Follower reads are particularly effective for globally distributed applications where read consistency can be slightly relaxed.
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.
✓
Enable follower reads
Why this is correct
Follower reads can serve reads from the nearest replica.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use stale reads
Why this is correct
Stale reads allow reading from any replica, reducing latency.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a multi-region configuration with a default leader
Why it's wrong here
This primarily helps write latency, not read latency.
✗
Use database partitioning
Why it's wrong here
Spanner does not use partitioning; it uses interleaved tables.
✗
Increase the number of nodes
Why it's wrong here
More nodes increase throughput but may not reduce latency.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that any multi-region configuration automatically reduces read latency, when in fact you must explicitly enable follower reads or stale reads to avoid routing reads to the leader replica.
Detailed technical explanation
How to think about this question
Follower reads leverage Cloud Spanner's TrueTime API to serve reads from non-leader replicas with bounded staleness (typically up to 15 seconds). This is implemented by setting a `staleness` value in the read request, which allows the read to be served from any replica that has caught up to that timestamp. In a real-world scenario, a global e-commerce platform can use follower reads to serve product catalog queries from local replicas, reducing latency from hundreds of milliseconds to single-digit milliseconds for users in distant regions.
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.
Monitor and optimize database performance — This question tests Monitor and optimize database performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable follower reads — Option A is correct because follower reads allow read requests to be served by any replica in a Cloud Spanner multi-region configuration, not just the leader replica. This reduces read latency by enabling reads to be processed from a replica that is geographically closer to the client, without incurring the round-trip time to the leader. Follower reads are particularly effective for globally distributed applications where read consistency can be slightly relaxed.
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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