Facing challenges with PostgreSQL and MySQL when it came to their rapid increase in data volume and compute, Metropolis needed a flexible and horizontally scalable data lake architecture to address their challenges associated with control and flexibility but still needed fine-grained security policies. They moved to a data lake architecture which includes AWS S3 for data storage, AWS Lake Formation for fine-grained security control, and Ahana for Presto for SQL on S3. Metropolis augments their own data with third-party sources like Zendesk, Heap, and Stripe, storing the resulting datasets in the data lake.