With the arrival of large cloud computing providers (hyperscalers) the first wave of managed database services arrived. These services mimicked what we had seen before in our data centers, our servers, and even our development devices running managed SQLServer, MySQL, Posgresql, MariaDB, Redis... But now a new generation of database services has arrived and they only make sense in these mega-suppliers. Horizontal autoscaling, replication in dozens of availability zones, minimal latencies, CAP theorem challenging... and on top of that multi-schema databases. This talk explains how Cosmos DB was born due to Microsoft's massive scaling needs with XBOX, the design decisions made and their impact, how it compares and how other competitors do it. Finally, an example of how my globally deployed side-project Apility.io (with no link to Microsoft) could benefit of Cosmos DB.