were can I find a training on CDH and especially the data relations?
You can find training for Pega Customer Decision Hub (CDH), including data relationships, on Pega Academy. Go to the Pega Academy website and log in with your Pega account. Search for “Customer Decision Hub” in the course catalog. Enroll in the learning path that includes CDH Foundations and Next-Best-Action Designer. These courses explain how data is structured and connected in CDH. Complete the guided modules and exercises to understand data relationships clearly.