- A
Stale reads with bounded staleness
Stale reads can be served by read-only replicas, improving read throughput and latency for non-critical queries.
- B
Global secondary indexes
Why wrong: Global indexes add overhead; local indexes are better for co-location.
- C
Interleaved tables
Why wrong: Interleaving is for storing related data together, not directly for read throughput of catalog queries.
- D
Local secondary indexes
Local indexes are co-located with the base table, reducing cross-split reads and improving performance.
- E
Strong reads
Why wrong: Strong reads go to the leader replica, increasing latency.
Question 951 of 980
Design Scalable and Highly Available Cloud Database Solutions →mediumMultiple SelectObjective-mapped
PCD Practice Question: Design Scalable and Highly Available Cloud Database Solutions
This PCD practice question tests your understanding of design scalable and highly available cloud database solutions. 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.
You are designing a globally distributed ecommerce platform that uses Cloud Spanner for order processing. The platform needs to support high read throughput with low latency for product catalog queries. Which two features should you use? (Choose TWO.)
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
✓
Stale reads with bounded staleness
Stale reads with bounded staleness (Option A) allow Cloud Spanner to serve read requests from any replica within a configurable time window (e.g., up to 15 seconds), avoiding the latency of contacting the leader replica. This dramatically increases read throughput for product catalog queries where near-real-time data is acceptable. Local secondary indexes (Option D) are co-located with the base table data in the same split, enabling efficient, low-latency queries on attributes within a single region without cross-node coordination.
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.
- ✓
Stale reads with bounded staleness
Why this is correct
Stale reads can be served by read-only replicas, improving read throughput and latency for non-critical queries.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Global secondary indexes
Why it's wrong here
Global indexes add overhead; local indexes are better for co-location.
- ✗
Interleaved tables
Why it's wrong here
Interleaving is for storing related data together, not directly for read throughput of catalog queries.
- ✓
Local secondary indexes
Why this is correct
Local indexes are co-located with the base table, reducing cross-split reads and improving performance.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Strong reads
Why it's wrong here
Strong reads go to the leader replica, increasing latency.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that all secondary indexes are global and that strong reads are always required for consistency, but the trap here is that for high-throughput, low-latency catalog queries, stale reads and local secondary indexes are the correct choices because they avoid leader bottlenecks and cross-split coordination.
Detailed technical explanation
How to think about this question
Cloud Spanner's stale reads leverage TrueTime to serve data from any replica that has caught up to the specified staleness bound, bypassing Paxos consensus for reads. Local secondary indexes in Spanner are stored in the same split as the base table rows, meaning a query using a local index can be served entirely from one tablet server without distributed coordination, which is critical for sub-millisecond latency at scale. In practice, a product catalog with millions of SKUs can use a local index on 'category' to serve filtered queries from a single node, while stale reads with a 5-second bound allow edge replicas to handle read traffic without hitting the leader in the primary region.
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.
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FAQ
Questions learners often ask
What does this PCD question test?
Design Scalable and Highly Available Cloud Database Solutions — This question tests Design Scalable and Highly Available Cloud Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Stale reads with bounded staleness — Stale reads with bounded staleness (Option A) allow Cloud Spanner to serve read requests from any replica within a configurable time window (e.g., up to 15 seconds), avoiding the latency of contacting the leader replica. This dramatically increases read throughput for product catalog queries where near-real-time data is acceptable. Local secondary indexes (Option D) are co-located with the base table data in the same split, enabling efficient, low-latency queries on attributes within a single region without cross-node coordination.
What should I do if I get this PCD 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.
About these practice questions
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Last reviewed: Jul 4, 2026
This PCD practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCD exam.
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