What is a difference between prometheus-postgres-exporter and PostgreSQL Data Source native plugin in Grafana?

Question

could you please explain the difference between prometheus-postgres-exporter and PostgreSQL Data Source native plugin in Grafana? And why do I need to use one over another. Unfortunately, couldn't find a proper explanation in the docs.

Thank you.

Answer 1

prometheus-postgres-exporter provides an endpoint for Prometheus to gather time series data about your database. This will probably include statistics like the number of tables, disk space used by the database, etc. You can then query and chart these datapoints over time in Grafana.

A PostgreSQL datasource in Grafana gives access to the database, but you can only run queries against the database. If you want to know how big the database was 2 weeks ago, you will not be able to get that by querying the database today. It only knows how big it is right now, not how big it was at another point in time.