Unfortunately for you, my work causes me to focus on the Microsoft stack, so I can't give any specific product recommendations. That being said, technology-wis

Unfortunately for you, my work causes me to focus on the Microsoft stack, so I can't give any specific product recommendations. That being said, technology-wise I can suggest a columnstore database to address some of your needs, particularly the need to use the distinct operator. The storage format of a columnstore lends itself to aggregation and distinct operations, with multiple orders of magnitude improvements possible compared to SQL. Additionally, traditional OLAP does not handle distinct operations all that wonderfully to begin with, so it likely wouldn't help you too much for that option. Further, you've not provided much detail about your dimensional model or your use case. It's worth exploring different fact table structures. The Kimball Data Warehouse books are always worth reading.