? MySQL Indexing Strategies

? Quick Overview

Indexing strategies in MySQL are techniques used to improve query performance by allowing the database engine to locate rows faster. Choosing the correct index type and structure is critical for large tables and high-performance applications.

? Key Concepts

• Indexes speed up SELECT, WHERE, JOIN, ORDER BY operations
• Indexes consume disk space and slow down INSERT, UPDATE, DELETE
• Choosing the right column order matters in composite indexes
• Too many indexes can degrade performance

? Syntax / Theory

• Single Column Index – Index on one column
• Composite Index – Index on multiple columns
• Unique Index – Ensures unique values
• Covering Index – Query uses only index data
• Index Selectivity – Ratio of unique values

? Code Example(s)

-- Creating a single-column index on email
CREATE INDEX idx_email ON users(email);

-- Creating a composite index on city and status
CREATE INDEX idx_city_status ON users(city, status);

-- Using EXPLAIN to analyze index usage
EXPLAIN SELECT * FROM users WHERE email = 'test@example.com';

? Live Output / Explanation

When indexes are used correctly, MySQL avoids full table scans and directly accesses matching rows. The EXPLAIN statement shows whether an index is being used and how many rows are examined.