Columnar Databases(e.x. Druid, Cassandra) expert consultancy

We are working on a project where we want to save statistics of users which needs partial updates but performant queries and writes operations. Need someone who has already worked with experience to give us consultancy. We will ask your recommendations for DB schema, configuration settings and best practices.

I am willing to pay as hourly basis for the project.
Please quote your hourly rates.