In the early days, the Uber backend system was a monolithic software architecture with several app servers and a single database. The system was mainly written in Python and used SQLALchemy as the ORM-layer to the database.

In early 2014, Uber faced the fact that given their trip growth —roughly 20% per month—the solution for storing trips was going to run out of steam, both in terms of storage volume and IOPS (Input/Output Operations Per Second) by the end of the year.

To fix this problem, project Mezzanine was launched. The whole system, which Uber simply calls Schemaless in homage to its design, is written in Python. The initial version took about 5 months from idea to production deployment.