Andrei Lepikhov builds an extension:
The extended statistics tool allows you to tell Postgres that additional statistics should be collected for a particular set of table columns. Why is this necessary? – I will try to quickly explain using the example of an open power plant database. For example, the fuel type (primary_fuel) used by a power plant is implicitly associated with the country’s name.
Click through to learn more about what extended statistics are and the nature of the extension.