people like to shit on document databases - but man oh man - the expressivity you get working with document databases combined with Ruby is unmatched. I know someone is gonna reply all you need is postgres - but yeah jsonb queries don't match mongo queries. & after all - most of the places I have worked the database writes / queries hit one or two tables and work loads got migrated to dynamodb. that includes socia media ingestion, iot streams and metasearch.

yeah if you need kimball style queries i.e olap then yeah use postgres with rails etc