The correct answer is to modify the query to include a WHERE clause that filters on an indexed column. This is because a query selecting all columns from a million-row table without a WHERE clause forces a full table scan, consuming excessive CPU and memory as the database reads every row. Adding a WHERE clause on an indexed column allows the database to use the index to locate only the matching rows, drastically reducing the number of rows scanned and lowering CPU usage. On the CompTIA ITF+ FC0-U61 exam, this scenario tests your understanding of basic database query optimization where clause techniques, often appearing in troubleshooting questions about performance bottlenecks. A common trap is to jump to complex solutions like caching or hardware upgrades, but the simplest fix is to filter data at the query level. Memory tip: “WHERE you filter, there you reduce the scan”—always start with a WHERE clause on an indexed column before adding layers of complexity.
FC0-U61 Software Development Concepts Practice Question
This FC0-U61 practice question tests your understanding of software development concepts. 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 a junior developer at a small company that uses a monolithic web application written in Python. The application runs on a single server and uses a MySQL database. Recently, the application has become slow during peak hours. The operations team reports high CPU usage on the server. You suspect that the database queries are not optimized. You propose to refactor the application to use a caching layer. However, your manager is concerned about adding complexity and suggests that you first optimize the most frequently executed queries. You review the code and find that the most frequent query selects all columns from a large table without a WHERE clause. The table has over 1 million rows. Which course of action should you take?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the query to include a WHERE clause that filters on an indexed column.
Option D is correct because the query selects all columns from a large table without a WHERE clause, which forces a full table scan. Adding a WHERE clause that filters on an indexed column reduces the number of rows scanned, dramatically improving performance without introducing the complexity of a caching layer. This directly addresses the high CPU usage caused by inefficient query execution.
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.
✗
Implement a caching layer using Redis.
Why it's wrong here
Caching is beneficial but adds complexity; optimizing the query is a more fundamental fix.
✗
Upgrade the server to have more CPU and RAM.
Why it's wrong here
Upgrading hardware is a temporary solution and does not fix inefficient queries.
✗
Add an index on all columns used in the query.
Why it's wrong here
Without a WHERE clause, an index is not used; the query still scans the entire table.
✓
Modify the query to include a WHERE clause that filters on an indexed column.
Why this is correct
Adding a WHERE clause reduces the amount of data retrieved, improving performance.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume adding an index always speeds up any query, but without a WHERE clause, an index is never used—the database still must scan the entire table.
Detailed technical explanation
How to think about this question
Without a WHERE clause, the MySQL query engine must perform a full table scan, reading every row from disk into memory, which consumes CPU and I/O. Adding a WHERE clause on an indexed column allows the database to use a B-tree index to locate rows quickly, reducing the number of rows examined from millions to a small subset. In a real-world scenario, even a simple filter like `WHERE id > 1000000` on a primary key index can cut query time from seconds to milliseconds.
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 practitioner preparing for the FC0-U61 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
Software Development Concepts — This question tests Software Development Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the query to include a WHERE clause that filters on an indexed column. — Option D is correct because the query selects all columns from a large table without a WHERE clause, which forces a full table scan. Adding a WHERE clause that filters on an indexed column reduces the number of rows scanned, dramatically improving performance without introducing the complexity of a caching layer. This directly addresses the high CPU usage caused by inefficient query execution.
What should I do if I get this FC0-U61 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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