Prometheus is an open-source monitoring system that stores metrics data locally, but it's not designed for long-term storage or scalability. To complement Prometheus and store metrics data in a scalable and durable way, users often turn to PostgreSQL, which can be used as a time-series database with the help of TimescaleDB. TimescaleDB improves on PostgreSQL by introducing new functions that are necessary for metrics analysis and providing 20x higher inserts, 2000x faster deletes, and 1.2-14,000x faster queries. The combination of Prometheus, PostgreSQL, and TimescaleDB allows users to store, analyze, and visualize metrics in a powerful and flexible way, with the ability to use PromQL or full SQL for querying, join metrics data with other data sources, and connect to other visualization tools like Tableau or Apache Spark. Additionally, a PostgreSQL adapter and a TimescaleDB database can be used together with Prometheus, making it easier to manage and visualize metrics data.