The correct answer is to create an index on the 'last_name' column. This works because a database index functions like a book’s index, allowing the database engine to locate rows that match a filter condition without performing a full table scan across millions of rows. By reducing the number of disk reads and CPU cycles needed for each query, an index directly improves database index query performance on large tables. On the CompTIA ITF+ FC0-U61 exam, this concept tests your understanding of how indexes optimize SELECT operations without altering application code—a common scenario in database administration. A frequent trap is assuming that adding more indexes always helps, but remember that indexes speed up reads while slightly slowing writes. For this exam, think of the mnemonic “INDEX = Instant Data EXtraction” to recall that indexes are the go-to solution for accelerating filtered queries on large datasets.
FC0-U61 Database Fundamentals Practice Question
This FC0-U61 practice question tests your understanding of database fundamentals. 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 company's database administrator notices that queries against a large customer table are running slowly. The table has millions of rows and is frequently filtered by the 'last_name' column. Which of the following is the BEST way to improve query performance without changing the application code?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an index on the 'last_name' column.
Creating an index on the 'last_name' column allows the database to locate rows matching filter conditions without scanning the entire table. This dramatically reduces I/O and CPU overhead for queries that filter by last_name, directly addressing the performance bottleneck without requiring any changes to application code.
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.
✗
Partition the table by row count.
Why it's wrong here
Partitioning organizes data into smaller segments but does not inherently accelerate searches on a specific column.
✗
Increase the database server's RAM.
Why it's wrong here
More RAM may improve caching but is not a targeted solution for column-based filtering; it is less effective than indexing.
✓
Create an index on the 'last_name' column.
Why this is correct
An index on the filtered column enables rapid row retrieval, significantly speeding up queries.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Denormalize the table to reduce joins.
Why it's wrong here
Denormalization introduces data redundancy and does not directly speed up filtering on 'last_name'.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose 'Increase the database server's RAM' because they think more memory will speed up all queries, but without an index the database still must read every row from disk or memory, and RAM alone cannot eliminate the need for a full table scan.
Detailed technical explanation
How to think about this question
A B-tree index on last_name stores sorted key values with pointers to the corresponding rows, enabling the database engine to perform a logarithmic search instead of a linear scan. In PostgreSQL, for example, a CREATE INDEX idx_customers_last_name ON customers (last_name); would allow the query planner to use an Index Scan or Index Only Scan, reducing complexity from O(n) to O(log n). Real-world scenarios often see query time drop from minutes to milliseconds when adding such an index on high-cardinality columns used in WHERE clauses.
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.
Database Fundamentals — This question tests Database Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create an index on the 'last_name' column. — Creating an index on the 'last_name' column allows the database to locate rows matching filter conditions without scanning the entire table. This dramatically reduces I/O and CPU overhead for queries that filter by last_name, directly addressing the performance bottleneck without requiring any changes to application code.
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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A database administrator adds an index on the 'Email' column of a 'Users' table. What is a likely consequence?
medium
A.Reduced storage space
B.Improved query performance for all queries
✓ C.Slower update operations on the table
D.Faster inserts on the table
Why C: Adding an index on the 'Email' column improves the speed of SELECT queries that filter or sort by that column, but it introduces overhead on write operations. Every time a row is inserted, updated, or deleted, the database must also update the index structure (e.g., a B-tree). This additional work makes UPDATE operations slower, which is why option C is correct.
Last reviewed: Jun 11, 2026
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This FC0-U61 practice question is part of Courseiva's free CompTIA 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 FC0-U61 exam.
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