This document discusses several use cases from banks and financial institutions using DataStax Enterprise (DSE). It describes challenges faced and approaches taken for: 1. A global merchant transactions use case involving 100TB of credit card charges and migrating from mainframe to DSE for scalability and high availability. 2. A global payments use case replacing an Exadata dependency and ingesting over 5,000 transactions per second into DSE. 3. A global billing use case scaling an Oracle Coherence deployment with DSE to aggregate usage data. It also discusses challenges around new technologies, data modeling, hardware requirements, and internal politics that were addressed when implementing DSE.