[srcreigh]

Is this ranking by # of orgs using Postgres, or relative total company value using Postgres, or some even more ambiguous effectiveness metric?

Answer: https://db-engines.com/en/ranking_definition

[srcreigh]

A DB system that works for professionals and doesn't require any public ecosystem of training materials won't be mentioned much in public.

[y4mi]

thats likely why they're also including mentions in job postings in their metric

> Number of job offers, in which the system is mentioned

its not a silver bullet, but I do think its at least somewhat representative of popularity.