MySQL Indexes: Performance Optimization Guide

MySQL Indexes: Performance Optimization

Learn how to use MySQL indexes to optimize database query performance.

What are Indexes?

Indexes are data structures that improve the speed of data retrieval operations on database tables.

Creating Indexes

Single Column Index

CREATE INDEX idx_email ON users(email);

Composite Index

CREATE INDEX idx_name_email ON users(name, email);

Unique Index

CREATE UNIQUE INDEX idx_username ON users(username);

When to Use Indexes

• Columns used in WHERE clauses
• Columns used in JOIN operations
• Columns used for sorting (ORDER BY)
• Frequently queried columns

Index Types

• PRIMARY KEY: Unique identifier for each row
• UNIQUE: Ensures no duplicate values
• INDEX: General purpose index
• FULLTEXT: For text searching

Performance Tips

• Don't over-index (slows down INSERT/UPDATE)
• Index columns with high selectivity
• Use EXPLAIN to analyze queries
• Monitor index usage