“Tool” may not be the right word; but being able to live monitor the vacuumer, to understand what table was taking how much space and why, to track min/mean/max

“Tool” may not be the right word; but being able to live monitor the vacuumer, to understand what table was taking how much space and why, to track min/mean/max execution time of queries, and, more generally, all the internal metrics that PgSQL exposes through a couple of SELECT has been a boon when debugging or optimizing.