I think "use postgres for everything" is a good solid foundation to start with (if you dont have a really good reason not to and know the exact use case beforeh

I think "use postgres for everything" is a good solid foundation to start with (if you dont have a really good reason not to and know the exact use case beforehand). Can redis, rabbitmq or solr etc do a better job for a specific user case, of course becasue they are dedicated tools for the job. But the question is, is the builtin tool in postgres "good enough"? And for many thing they are. I see postgres like a tractor. It's the most important machine and you can attach alot of different equipment's to get alot of jobs done. Some times you notice a task need a specific machine that the tractor is not suited for, then you invest in that machine. To invest in all specialized machines from the beginning just because they can do one single job better than the tractor is not an efficient way of farming, there is a price to have all those machines too, that does not necessarily result in a better outcome.