- A
The index is a local index without the STORING clause
Why wrong: Local indexes are interleaved and often faster; the issue is more likely with global indexes.
- B
The Spanner instance is under-provisioned
Why wrong: Under-provisioning might cause high latency, but the symptom of full table scans points to index design.
- C
The index is a global index without the STORING clause, causing index join
Global indexes require a join with the base table to retrieve columns not stored in the index, leading to scans.
- D
The index is defined on a composite key that is not selective
Why wrong: While selectivity matters, the primary issue is the missing STORING clause forcing table scans.
Question 564 of 980
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.
A Cloud Spanner instance is experiencing high latency for global secondary index queries. The team notices that queries on the secondary index are performing full table scans instead of index scans. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
✓
The index is a global index without the STORING clause, causing index join
In Cloud Spanner, secondary indexes can be local (interleaved with parent) or global (non-interleaved). If an index is defined as a global index, queries might still need to join with the base table unless the index includes all needed columns. Without the `STORING` clause, Spanner must fetch additional columns from the base table, causing the query to scan the base table.
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.
- ✗
The index is a local index without the STORING clause
Why it's wrong here
Local indexes are interleaved and often faster; the issue is more likely with global indexes.
- ✗
The Spanner instance is under-provisioned
Why it's wrong here
Under-provisioning might cause high latency, but the symptom of full table scans points to index design.
- ✓
The index is a global index without the STORING clause, causing index join
Why this is correct
Global indexes require a join with the base table to retrieve columns not stored in the index, leading to scans.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The index is defined on a composite key that is not selective
Why it's wrong here
While selectivity matters, the primary issue is the missing STORING clause forcing table scans.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Design Scalable and Highly Available Cloud Database Solutions — study guide chapter
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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: The index is a global index without the STORING clause, causing index join — In Cloud Spanner, secondary indexes can be local (interleaved with parent) or global (non-interleaved). If an index is defined as a global index, queries might still need to join with the base table unless the index includes all needed columns. Without the `STORING` clause, Spanner must fetch additional columns from the base table, causing the query to scan the base table.
What should I do if I get this PCD question wrong?
Identify which PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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