A Web hosting company has been using a custom built data store modeled on the sparse multidimensional array data structure. The CIO no longer wants to pay to develop and maintain a custom data store. Instead, the CIO wants a managed database service if possible and if not, they want to use a well supported open source database that is also based on sparse multidimensional array data structure. The Web hosting company is already using Google Cloud Compute Engine, Cloud Storage, and Kubernetes Engine. What would you recommend to the company?