Database Optimization Tips

Database performance is critical for application speed. This guide covers essential optimization techniques for common databases.

General Optimization Principles

1. Indexing Strategy

Proper indexing dramatically improves query performance.

Good Indexing:

• Index foreign keys
• Index frequently queried columns
• Index columns used in WHERE clauses
• Use composite indexes for multi-column queries

Avoid:

• Over-indexing (impacts write performance)
• Indexing small tables
• Indexing columns with low cardinality

2. Query Optimization

Write efficient queries:

-- BAD: SELECT *
SELECT * FROM users;

-- GOOD: Select only needed columns
SELECT id, email, name FROM users;

3. Connection Pooling

Reuse database connections instead of creating new ones:

• Reduces connection overhead
• Improves response time
• Better resource utilization

PostgreSQL Optimization

Configuration Tuning

Edit postgresql.conf:

# Memory Settings
shared_buffers = 256MB
effective_cache_size = 1GB
work_mem = 16MB
maintenance_work_mem = 64MB

# Connection Settings
max_connections = 100

# Query Planning
random_page_cost = 1.1
effective_io_concurrency = 200

Useful Queries

Find Slow Queries:

SELECT query, calls, total_time, mean_time
FROM pg_stat_statements
ORDER BY mean_time DESC
LIMIT 10;

Check Table Sizes:

SELECT
  schemaname,
  tablename,
  pg_size_pretty(pg_total_relation_size(schemaname||'.'||tablename))
FROM pg_tables
ORDER BY pg_total_relation_size(schemaname||'.'||tablename) DESC;

MySQL/MariaDB Optimization

Configuration Tuning

Edit my.cnf:

[mysqld]
# InnoDB Settings
innodb_buffer_pool_size = 1G
innodb_log_file_size = 256M
innodb_flush_method = O_DIRECT

# Query Cache
query_cache_type = 1
query_cache_size = 128M

# Connection Settings
max_connections = 150

Useful Commands

Analyze Query Performance:

EXPLAIN SELECT * FROM users WHERE email = 'user@example.com';

Check Index Usage:

SHOW INDEX FROM users;

Maintenance Tasks

Regular Vacuum (PostgreSQL)

-- Manual vacuum
VACUUM ANALYZE users;

-- Full vacuum (requires lock)
VACUUM FULL users;

Optimize Tables (MySQL)

OPTIMIZE TABLE users;

Monitoring

Key Metrics to Track

1. Query Performance

   • Average query time
   • Slow query count
   • Query cache hit rate

2. Resource Usage

   • CPU utilization
   • Memory usage
   • Disk I/O

3. Connection Stats

   • Active connections
   • Connection errors
   • Max connections reached

Monitoring Tools

• pgAdmin (PostgreSQL)
• phpMyAdmin (MySQL)
• Grafana (Universal)
• pg_stat_statements (PostgreSQL)
• Performance Schema (MySQL)

Backup Strategy

PostgreSQL Backup

# Full backup
pg_dump -U postgres dbname > backup.sql

# Compressed backup
pg_dump -U postgres dbname | gzip > backup.sql.gz

MySQL Backup

# Full backup
mysqldump -u root -p dbname > backup.sql

# All databases
mysqldump -u root -p --all-databases > backup.sql

Scaling Strategies

Vertical Scaling

• Upgrade to NVMe storage
• Increase RAM
• Add CPU cores

Horizontal Scaling

• Read replicas
• Sharding
• Connection pooling

Caching Layer

• Redis for session data
• Memcached for query results
• Application-level caching

Best Practices Checklist

• Indexes on foreign keys
• Regular VACUUM/OPTIMIZE
• Automated backups configured
• Monitoring tools set up
• Connection pooling enabled
• Query logging for slow queries
• Regular performance reviews
• Database updates applied

Performance Testing

Load Testing Tools

• pgbench (PostgreSQL)
• sysbench (MySQL)
• Apache JMeter
• wrk or hey for API testing

Example pgbench Test

# Initialize test database
pgbench -i -s 50 testdb

# Run benchmark
pgbench -c 10 -j 2 -t 1000 testdb

Troubleshooting Common Issues

High CPU Usage

• Check for missing indexes
• Identify slow queries
• Optimize query plans

High Memory Usage

• Adjust buffer pool size
• Check for memory leaks
• Review connection count

Slow Queries

• Add appropriate indexes
• Rewrite complex queries
• Update database statistics

Conclusion

Database optimization is an ongoing process. Regular monitoring, maintenance, and tuning ensure optimal performance as your application grows.

Need help optimizing your database? Contact our support team for assistance.