Prometheus is a widely used open-source monitoring and alerting system that solves monitoring problems in a simple and effective way. However, operating Prometheus can be challenging, especially when it comes to long-term storage and managing high-availability. To address these challenges, PostgreSQL + TimescaleDB can be used as a shared remote storage and single source of ground truth for an HA Prometheus deployment. The prometheus-postgresql-adapter aims to solve this problem by adding support for leader election, which allows one PostgreSQL/TimescaleDB instance to serve as the shared remote storage and single source of ground truth for all HA Prometheus deployments. This setup provides several benefits, including avoiding data loss and a single point of failure, avoiding missing critical alerts generated by an Alertmanager, and replicating Prometheus data while ensuring that data is not fully consistent between replicas. The adapter can be configured to run in read-only mode, and recent optimizations have improved write performance by 6x compared to previous versions.