Join Performance Optimization: Real-World

Production queries with slow joins need optimization. Understanding indexing, execution plans, and optimization techniques is essential for database performance.

E-commerce Query Optimization

Product catalog query joining 5 tables runs slowly, affecting user experience. Need comprehensive optimization strategy.

Strategic indexing, query restructuring, and covering indexes

-- Optimized query with proper indexes

CREATE INDEX idx_products_category_status ON products(category_id, status, price);

CREATE INDEX idx_inventory_product ON inventory(product_id, quantity);

CREATE INDEX idx_reviews_product_rating ON reviews(product_id, rating, status);

SELECT

p.product_name,

p.price,

i.quantity,

AVG(r.rating) as avg_rating

FROM products p

INNER JOIN inventory i ON p.product_id = i.product_id

LEFT JOIN reviews r ON p.product_id = r.product_id AND r.status = 'approved'

WHERE p.category_id = 1

AND p.status = 'active'

AND i.quantity > 0

GROUP BY p.product_id, p.product_name, p.price, i.quantity

ORDER BY avg_rating DESC NULLS LAST;

Query time reduced from 8 seconds to 200ms. Improved user experience and reduced server load.

All