> In the 2000s, the conventional wisdom selected MySQL because rising tech stars like Google and Facebook were using it. Then in the 2010s, it was MongoDB because non-durable writes made it “webscale“. In the last five years, PostgreSQL has become the Internet’s darling DBMS. And for good reasons!
Different DB's, different strengths and it's not a zero sum came as implied. MySQL was popular before Google was born - we used it heavily at eToys in the 90s for massive transaction volume and replacing it with Oracle was one of the reasons for the catastrophic failure of eToys circa 2001. MongoDB gained traction not because it's an alternative to MySQL or PostgreSQL. And PostgreSQL's marketshare today is on a par with Mongo and both are dwarfed by MySQL which IMO is the true darling of web DB's given it's global popularity.
Honestly I think it only gained traction because many Node devs refused to learn SQL and the document model is familiar because it's closer to JSON data.
These days Mongo is good but that wasn't the case back 10+ years ago.
I think Mongo became popular because it's ad tech and those guys knew how to be buzzword compliant. JSON-esque documents are one thing, but Mongo is Javascript to the core. All of a sudden your JS devs don't have to learn SQL they can just shit out some queries in javascript. Of course that came with some pretty severe drawbacks.