Full-text indexes in MySQL - Mini Project: Build & Apply

Creating and Using Full-text Indexes in MySQL

📖 Scenario: You are building a simple article search feature for a blog website. The blog stores articles with titles and content. To help users find articles by keywords quickly, you want to use MySQL's full-text search capability.

🎯 Goal: Build a MySQL table for articles, add a full-text index on the title and content columns, and write a query to search articles by keywords using the full-text index.

📋 What You'll Learn

Create a table named articles with columns id, title, and content

Add a full-text index on the title and content columns

Insert sample articles with exact titles and content

Write a query using MATCH(title, content) AGAINST() to find articles matching a keyword

💡 Why This Matters

🌍 Real World

Full-text indexes are used in blogs, news sites, and e-commerce to quickly find relevant text content based on user search keywords.

💼 Career

Knowing how to create and use full-text indexes is important for database developers and backend engineers to optimize search features in applications.

1

Create the articles table

Create a table called articles with these columns: id as an integer primary key that auto-increments, title as a VARCHAR(100), and content as TEXT.

MySQL

-- Your code here to create the articles table

Hint

Use CREATE TABLE with id INT AUTO_INCREMENT PRIMARY KEY and the specified column types.

2

Add a full-text index on title and content

Add a full-text index named ft_index on the title and content columns of the articles table.

MySQL

CREATE TABLE articles (
  id INT AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(100),
  content TEXT
);
-- Your code here to add the full-text index

Hint

Add FULLTEXT KEY ft_index (title, content) inside the table definition.

3

Insert sample articles

Insert these exact rows into the articles table: (1, 'MySQL Tutorial', 'Learn how to use MySQL databases.'), (2, 'Full-text Search', 'Full-text indexes help search text quickly.'), and (3, 'Database Basics', 'Introduction to databases and SQL.').

MySQL

CREATE TABLE articles (
  id INT AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(100),
  content TEXT,
  FULLTEXT KEY ft_index (title, content)
);
-- Your code here to insert sample articles

Hint

Use INSERT INTO articles (id, title, content) VALUES with the exact rows.

4

Write a full-text search query

Write a SELECT query to find all articles where the title or content matches the keyword 'search' using the full-text index with MATCH(title, content) AGAINST('search').

MySQL

CREATE TABLE articles (
  id INT AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(100),
  content TEXT,
  FULLTEXT KEY ft_index (title, content)
);

INSERT INTO articles (id, title, content) VALUES
(1, 'MySQL Tutorial', 'Learn how to use MySQL databases.'),
(2, 'Full-text Search', 'Full-text indexes help search text quickly.'),
(3, 'Database Basics', 'Introduction to databases and SQL.');

-- Your code here to write the full-text search query

Hint

Use SELECT * FROM articles WHERE MATCH(title, content) AGAINST('search') to find matching articles.

Practice

1. What is the main purpose of a FULLTEXT index in MySQL?

easy

A. To speed up searching for words inside text columns

B. To enforce uniqueness on text columns

C. To sort text columns alphabetically

D. To compress text data for storage

Solution

1. Step 1: Understand what FULLTEXT indexes do

   FULLTEXT indexes are designed to make searching for words inside large text columns faster and more efficient.

2. Step 2: Compare with other index types

   Unlike unique or sorting indexes, FULLTEXT indexes focus on text search, not uniqueness or ordering.

3. Final Answer:

   To speed up searching for words inside text columns -> Option A

4. Quick Check:

   FULLTEXT index = speeds up text search [OK]

Hint: FULLTEXT indexes are for fast word searches in text columns [OK]

Common Mistakes:

• Confusing FULLTEXT with UNIQUE index
• Thinking FULLTEXT sorts data
• Assuming FULLTEXT compresses data

2. Which of the following is the correct syntax to create a FULLTEXT index on the column description in a table products?

easy

A. CREATE INDEX idx_desc FULLTEXT ON products(description);

B. CREATE INDEX idx_desc ON products(description) FULLTEXT;

C. CREATE FULLTEXT INDEX idx_desc ON products(description);

D. CREATE FULLTEXT ON products(description) INDEX idx_desc;

Solution

1. Step 1: Recall correct FULLTEXT index syntax

   The correct syntax is: CREATE FULLTEXT INDEX index_name ON table_name(column_name);

2. Step 2: Match syntax with options

   CREATE FULLTEXT INDEX idx_desc ON products(description); matches the correct syntax exactly.

3. Final Answer:

   CREATE FULLTEXT INDEX idx_desc ON products(description); -> Option C

4. Quick Check:

   CREATE FULLTEXT INDEX ... ON ... [OK]

Hint: FULLTEXT index syntax: CREATE FULLTEXT INDEX name ON table(column) [OK]

Common Mistakes:

• Placing FULLTEXT keyword after INDEX
• Using wrong order of keywords
• Omitting INDEX keyword

3. Given a table articles with a FULLTEXT index on the content column, what will the following query return?

SELECT id FROM articles WHERE MATCH(content) AGAINST('database');

medium

A. Syntax error because MATCH() requires multiple columns

B. All article IDs sorted alphabetically by content

C. All article IDs where content exactly equals 'database'

D. All article IDs where the word 'database' appears in content

Solution

1. Step 1: Understand MATCH() AGAINST() usage

   This function searches the FULLTEXT indexed column for the given word or phrase.

2. Step 2: Interpret the query result

   The query returns IDs of rows where 'database' appears anywhere in the content column.

3. Final Answer:

   All article IDs where the word 'database' appears in content -> Option D

4. Quick Check:

   MATCH() AGAINST() = full-text search result [OK]

Hint: MATCH() AGAINST() finds rows containing the search word [OK]

Common Mistakes:

• Thinking it matches exact whole content
• Assuming it sorts results
• Believing MATCH() needs multiple columns

4. You wrote this query but it returns no results even though matching rows exist:

SELECT * FROM posts WHERE MATCH(body) AGAINST('the');

The body column has a FULLTEXT index. What is the likely problem?

medium

A. AGAINST() requires the IN BOOLEAN MODE modifier

B. The word 'the' is too common and ignored by default stopword list

C. FULLTEXT index must be created on multiple columns

D. MATCH() cannot be used on a single column

Solution

1. Step 1: Recall FULLTEXT stopword behavior

   MySQL ignores very common words (stopwords) by default in FULLTEXT searches.

2. Step 2: Understand why no results appear

   If 'the' is in the stopword list, the search ignores it, returning no matches.

3. Final Answer:

   The word 'the' is too common and ignored by default stopword list -> Option B

4. Quick Check:

   Stopwords cause no results for common words [OK]

Hint: Common words may be ignored by FULLTEXT stopword list [OK]

Common Mistakes:

• Thinking MATCH() needs multiple columns
• Assuming IN BOOLEAN MODE is always required
• Believing FULLTEXT index must cover multiple columns

5. You want to find rows in the reviews table where the comment column contains either 'fast' or 'reliable'. The comment column has a FULLTEXT index. Which query correctly finds these rows using boolean mode?

hard

A. SELECT * FROM reviews WHERE MATCH(comment) AGAINST('fast | reliable' IN BOOLEAN MODE);

B. SELECT * FROM reviews WHERE MATCH(comment) AGAINST('+fast +reliable' IN BOOLEAN MODE);

C. SELECT * FROM reviews WHERE MATCH(comment) AGAINST('fast reliable' IN BOOLEAN MODE);

D. SELECT * FROM reviews WHERE MATCH(comment) AGAINST('"fast reliable"' IN BOOLEAN MODE);

Solution

1. Step 1: Understand boolean mode operators

   In boolean mode, | means OR, + means AND, and quotes mean phrase search.

2. Step 2: Identify correct OR query

   To find rows containing either 'fast' OR 'reliable', use 'fast | reliable'.

3. Step 3: Check other options

   SELECT * FROM reviews WHERE MATCH(comment) AGAINST('fast reliable' IN BOOLEAN MODE); searches for both words but not as OR; SELECT * FROM reviews WHERE MATCH(comment) AGAINST('+fast +reliable' IN BOOLEAN MODE); requires both words; SELECT * FROM reviews WHERE MATCH(comment) AGAINST('"fast reliable"' IN BOOLEAN MODE); searches exact phrase.

4. Final Answer:

   SELECT * FROM reviews WHERE MATCH(comment) AGAINST('fast | reliable' IN BOOLEAN MODE); -> Option A

5. Quick Check:

   Boolean OR uses | operator [OK]

Hint: Use | for OR in boolean full-text searches [OK]

Common Mistakes:

• Using space for OR instead of |
• Using + which means AND
• Using quotes for phrase instead of OR