👉What is an Index in MySQL?
MySQL Index Tutorial: A MySQL Index is a database feature that organizes data in a structured way, making search queries significantly faster. It acts like an alphabetical index in a book, helping the database locate records efficiently instead of scanning entire tables.
Why Use an Index?
🔹 Speeds up search queries by avoiding full table scans.
🔹 Improves database performance without upgrading hardware.
🔹 Efficient sorting for ORDER BY queries.
🔹 Ideal for large datasets where frequent searches occur.
⚠ Downside: Indexes slow down INSERT and UPDATE operations because they require additional updates when data changes.
👉How to Create an Index in MySQL
Indexes can be created in two ways:
When creating a table
After the table is created
1. Create an Index at Table Creation
Let’s create an indexed table called members_indexed, optimizing searches on full_names:
sql
CREATE TABLE members_indexed (
membership_number INT(11) NOT NULL AUTO_INCREMENT,
full_names VARCHAR(150) DEFAULT NULL,
gender VARCHAR(6) DEFAULT NULL,
date_of_birth DATE DEFAULT NULL,
physical_address VARCHAR(255) DEFAULT NULL,
postal_address VARCHAR(255) DEFAULT NULL,
contact_number VARCHAR(75) DEFAULT NULL,
email VARCHAR(255) DEFAULT NULL,
PRIMARY KEY (membership_number),
INDEX (full_names) — Creates an index on ‘full_names’
) ENGINE=InnoDB;
This ensures search queries on full_names run faster!
2. Add an Index to an Existing Table
MySQL Index Tutorial: If a table already exists and queries are slow, add an index to commonly searched columns:
sql
CREATE INDEX index_name ON table_name(column_name);
🔹 Example: If search queries on movies table are slow, indexing the title column helps:
sql
CREATE INDEX title_index ON movies(title);
✅ Now, searching for a movie title will be much faster!
👉How to View Indexes in a Table
MySQL Index Tutorial: To check all indexes defined on a table, use:
sql
SHOW INDEXES FROM table_name;
🔹 Example: Check indexes on the movies table:
sql
SHOW INDEXES FROM movies;
This displays all existing indexes, including primary and foreign keys.
👉How to Drop (Remove) an Index in MySQL
MySQL Index Tutorial: Sometimes, indexes hurt performance when tables are frequently updated. If an index is unnecessary, remove it:
sql
DROP INDEX index_name ON table_name;
🔹 Example: Remove the index on full_names from members_indexed:
sql
DROP INDEX full_names ON members_indexed;
✅ This removes indexing overhead, improving INSERT and UPDATE performance.
👉Key Takeaways: Why Indexing Matters
✔ MySQL Index Tutorial: Improves query speed by making searches more efficient.
✔ Indexes can be created or added later based on search needs.
✔ Multiple indexes can be used for optimized searches.
✔ Indexes should be used wisely, as they slow down updates.
Optimize your MySQL database with indexing and experience faster performance!
Need further clarification? Let me know!
