- A
Create an index exemption for the collection to allow multi-field queries.
Why wrong: Index exemptions are used to exclude fields from automatic indexing, not to enable multi-field queries.
- B
Add a third field to the query to make it more specific.
Why wrong: Adding more fields would require an even more complex composite index, not solve the current issue.
- C
Create a composite index on the 'status' and 'createdAt' fields.
Composite indexes are required for multi-field queries. Firestore does not automatically create them.
- D
Ensure that single-field indexes exist for both 'status' and 'createdAt'.
Why wrong: Single-field indexes exist automatically, but they do not support combined queries on multiple fields.
Question 984 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.
Your Firestore database in Native mode is used by a mobile app. You need to query a collection where documents are filtered by two fields: 'status' (string) and 'createdAt' (timestamp). The query is not performing as expected. What action is required?
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 'createdAt' fields.
Firestore in Native mode requires a composite index to efficiently query documents filtered by multiple fields, such as 'status' and 'createdAt'. Without this index, the query may fail or perform poorly, as Firestore cannot combine separate single-field indexes for equality and range filters. Option C is correct because creating a composite index on both fields enables the query to run as expected.
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 for the collection to allow multi-field queries.
Why it's wrong here
Index exemptions are used to exclude fields from automatic indexing, not to enable multi-field queries.
- ✗
Add a third field to the query to make it more specific.
Why it's wrong here
Adding more fields would require an even more complex composite index, not solve the current issue.
- ✓
Create a composite index on the 'status' and 'createdAt' fields.
Why this is correct
Composite indexes are required for multi-field queries. Firestore does not automatically create them.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Ensure that single-field indexes exist for both 'status' and 'createdAt'.
Why it's wrong here
Single-field indexes exist automatically, but they do not support combined queries on multiple fields.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that single-field indexes are sufficient for multi-field queries, but Firestore requires composite indexes for any query combining equality and range filters on different fields.
Detailed technical explanation
How to think about this question
Firestore uses a query engine that relies on indexes to scan documents efficiently. For a query with an equality filter on 'status' and an order/range filter on 'createdAt', the engine must read documents in sorted order by 'createdAt' within each 'status' value, which requires a composite index on ('status', 'createdAt'). Without it, Firestore returns an error or falls back to a full collection scan, leading to poor performance or failure. In production, failing to create composite indexes for common query patterns can cause unexpected latency and increased read costs.
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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Manage Database Solutions practice 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 'createdAt' fields. — Firestore in Native mode requires a composite index to efficiently query documents filtered by multiple fields, such as 'status' and 'createdAt'. Without this index, the query may fail or perform poorly, as Firestore cannot combine separate single-field indexes for equality and range filters. Option C is correct because creating a composite index on both fields enables the query to run as expected.
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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