Database Optimization Tips for High-Traffic PHP Applications

When Queries Slow Down

As your application grows, database performance becomes critical. Here are battle-tested optimization techniques.

Indexing Strategy

• Add indexes on columns used in WHERE clauses
• Use composite indexes for multi-column queries
• Avoid over-indexing (slows down writes)

Query Optimization

-- Use EXPLAIN to analyze queries
EXPLAIN SELECT * FROM users WHERE email = "test@example.com";

-- Avoid SELECT *
SELECT id, name, email FROM users WHERE active = 1;

-- Use LIMIT for pagination
SELECT * FROM posts ORDER BY created_at DESC LIMIT 10 OFFSET 20;

Caching Strategies

• Query Cache: Cache frequent query results
• Redis/Memcached: In-memory caching
• Application Cache: Cache computed values

Connection Pooling

Use persistent connections for high-traffic applications:

$pdo = new PDO($dsn, $user, $pass, [
    PDO::ATTR_PERSISTENT => true
]);

A well-optimized database is the foundation of a fast application.