[mace]

I think a fair summary is "We had a few problems with PostgreSQL mostly due to our rapid growth. We rethought the problem and changed the way we use a relational database for large-scale storage and are now using MySQL as a dumb key-value store."

The conclusion reinforces this: "Postgres served us well in the early days of Uber, but we ran into significant problems scaling Postgres with our growth."

I read this a both endorsement of PostgreSQL as well as highlighting some of the problems that any large-scale use of it would run into.