- A
Create an index exemption to improve query performance.
Why wrong: Index exemptions are used to exclude indexes on arrays and maps, not to improve performance.
- B
Use a collection group query to bypass index requirements.
Why wrong: Collection group queries also need indexes; they do not bypass index requirements.
- C
Rely on automatic single-field indexes; they will cover the query.
Why wrong: Single-field indexes are not sufficient for combined filter and order queries.
- D
Create a composite index on the 'status' and 'timestamp' fields.
A composite index is required for queries with both an equality filter and an order by on different fields.
Question 339 of 1,000
PCDOE Manage Database Solutions Practice Question
This PCDOE practice question tests your understanding of manage database solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 Firestore in Native mode for their application. They need to query a collection where documents must match a specific field value and be sorted by a different field. The query filters on 'status' and orders by 'timestamp'. What should the engineer do to ensure the query performs optimally?
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
✓
Create a composite index on the 'status' and 'timestamp' fields.
Option D is correct because Firestore requires a composite index when a query includes both an equality filter on one field (status) and an order by clause on a different field (timestamp). Without this composite index, Firestore cannot efficiently satisfy both the filter and the sort order in a single index scan, leading to suboptimal performance or query failure. Creating a composite index on (status, timestamp) allows Firestore to use a single index to match the filter and return results in the requested order.
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.
- ✗
Create an index exemption to improve query performance.
Why it's wrong here
Index exemptions are used to exclude indexes on arrays and maps, not to improve performance.
- ✗
Use a collection group query to bypass index requirements.
Why it's wrong here
Collection group queries also need indexes; they do not bypass index requirements.
- ✗
Rely on automatic single-field indexes; they will cover the query.
Why it's wrong here
Single-field indexes are not sufficient for combined filter and order queries.
- ✓
Create a composite index on the 'status' and 'timestamp' fields.
Why this is correct
A composite index is required for queries with both an equality filter and an order by on different fields.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that automatic single-field indexes are sufficient for all queries, but the trap here is that queries combining an equality filter and an order by on different fields always require a composite index.
Detailed technical explanation
How to think about this question
Firestore uses a B-tree-like index structure where composite indexes store document references sorted by the concatenation of the indexed fields. When you create a composite index on (status ASC, timestamp DESC), Firestore can efficiently perform an equality scan on status and then traverse the timestamp portion in the specified order without additional sorting. In real-world scenarios, failing to create this composite index forces Firestore to perform a full collection scan and sort in memory, which can exceed query limits or cause timeouts for large datasets.
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.
- →
Manage Database Solutions — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this PCDOE question test?
Manage Database Solutions — This question tests Manage Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a composite index on the 'status' and 'timestamp' fields. — Option D is correct because Firestore requires a composite index when a query includes both an equality filter on one field (status) and an order by clause on a different field (timestamp). Without this composite index, Firestore cannot efficiently satisfy both the filter and the sort order in a single index scan, leading to suboptimal performance or query failure. Creating a composite index on (status, timestamp) allows Firestore to use a single index to match the filter and return results in the requested order.
What should I do if I get this PCDOE 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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Last reviewed: Jul 4, 2026
This PCDOE 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 PCDOE exam.
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