Database Performance Monitoring Setup

Set up database monitoring for:

Database: [PostgreSQL/MySQL/MongoDB]
Deployment: [AWS RDS/GCP Cloud SQL/Self-hosted]
Monitoring Stack: [Prometheus/Datadog/CloudWatch/etc.]

Current Issues:
[DESCRIBE PERFORMANCE PROBLEMS IF ANY]

Metrics Needed:
- Query performance
- Connection usage
- Replication lag
- Resource utilization

Please provide:
1. Key metrics to monitor with thresholds
2. Monitoring agent/exporter setup
3. Dashboard configuration
4. Alert rules and escalation
5. Slow query logging and analysis
6. Capacity planning metrics