You can collect metrics from both RDS and PostgreSQL directly to gain comprehensive insights into database performance. To access RDS metrics, you can use the AWS Management Console, AWS CLI, or a CloudWatch-compatible monitoring tool. In the console, filter by dimensions like database name or instance class, and graph metrics over time. The AWS CLI provides a quick way to query specific CloudWatch metrics from your RDS database instances using the `get-metric-statistics` command. You can also set up an RDS PostgreSQL monitoring tool that integrates with CloudWatch to gain a broader view of health and performance across all services and applications. To access native PostgreSQL metrics, you'll need to connect to your RDS instance, configure inbound rules for security group access, and use the PostgreSQL statistics collector's statistics views. The `pg_stat_database`, `pg_stat_user_tables`, `pg_stat_user_indexes`, and `pg_stat_bgwriter` views provide useful data on database activity, connections, locks, and disk usage. You can query these views using `psql` or write custom queries to gain more granular insights into your database's performance. By combining RDS metrics with PostgreSQL statistics, you'll have a comprehensive understanding of your database's health and performance, enabling you to optimize and troubleshoot applications that rely on your database instances.