Postgres served us well in the early days of Uber, but we ran into significant problems scaling Postgres with our growth. In this article, we’ll explore some of the drawbacks we found with Postgres and explain the decision to build Schemaless and other backend services on top of MySQL.
Why Uber Engineering Switched from Postgres to MySQL →
The mailinglist post “Why we lost Uber as a user” that came as a response is also worth a read.