Indexing Best Practices

Master database performance optimization through effective indexing strategies.

Database indexes are crucial for optimizing query performance. Like a book's index, database indexes help quickly locate data without scanning entire tables. Understanding how to create and maintain effective indexes is essential for building high-performance applications.

Basic Indexing

Start with simple indexes for frequently queried columns:

-- Create a basic index
CREATE INDEX idx_users_email 
ON users(email);

-- Create a unique index
CREATE UNIQUE INDEX idx_users_username 
ON users(username);

When to Use

•Columns used in WHERE clauses
•Foreign key relationships
•Unique constraints

Composite Indexes

Create multi-column indexes for combined query conditions:

-- Create a composite index
CREATE INDEX idx_orders_customer_date 
ON orders(customer_id, order_date);

-- Query using the composite index
SELECT * FROM orders 
WHERE customer_id = 100 
  AND order_date >= '2024-01-01';

Benefits

•Optimizes multi-column queries
•Reduces index maintenance
•Improves query selectivity

Column Order

•Most selective columns first
•Consider query patterns
•Match WHERE clause order

Covering Indexes

Include additional columns to fully satisfy queries from the index:

-- Create a covering index
CREATE INDEX idx_products_category_price 
ON products(category_id, price) 
INCLUDE (name, description);

-- Query fully covered by the index
SELECT name, description, price 
FROM products 
WHERE category_id = 5 
  AND price > 100;

Key Considerations

•Balance coverage vs. size
•Include frequently selected columns
•Consider maintenance overhead

Analyzing Index Usage

Monitor and analyze index performance:

-- Check index usage
EXPLAIN ANALYZE 
SELECT * FROM orders 
WHERE customer_id = 100;

-- Get index statistics
SELECT 
    schemaname,
    tablename,
    indexname,
    idx_scan,
    idx_tup_read,
    idx_tup_fetch
FROM pg_stat_user_indexes;

Index Maintenance

Regular maintenance ensures optimal index performance:

-- Rebuild index
ALTER INDEX idx_users_email REBUILD;

-- Reorganize index
ALTER INDEX idx_users_email REORGANIZE;

-- Update statistics
ANALYZE users;

Maintenance Tasks

•Regular rebuilding
•Statistics updates
•Fragmentation monitoring

Warning Signs

•High fragmentation
•Outdated statistics
•Degrading performance

Practice Examples

Try these examples to practice index creation and analysis:

Creating an Optimal Index

CREATE INDEX idx_orders_customer_status ON orders(customer_id, status) INCLUDE (order_date, total_amount);

Index for Range Queries

CREATE INDEX idx_products_price ON products(category_id, price) WHERE price > 0;

Analyzing Index Performance

EXPLAIN ANALYZE SELECT * FROM orders WHERE customer_id = 100 AND status = 'pending';

Next Steps

Continue improving your database optimization skills:

Transaction Management →

Learn about ACID properties and consistency

Working with JOINs →

Optimize queries across multiple tables