Uploading a .csv to a NoSQL cluster - batch faster than consumer/producer
I'm not an expert in cluster operations, so I'll review the parts I do know.

Single-letter variable names

These are a big no-no unless the only thing you're worried about is not being fireable. Any maintenance programmer looking in the middle of a chunk of code is not going to be happy jumping back and forwards to definitions to work out what on earth r is when you could just as easily have written row.

var

You should use var when the right hand side of an assignment makes the type obvious. e.g.

int uniqueIdentifier = 1;

should be

var uniqueIdentifier = 1;

This is recommended because if you decide to change the type (e.g. to a GUID), you only have to change it in one place.

Style

In C# the general naming guideline for methods is to use PascalCase. This is, of course, optional (as with any point on style), but recommended to make code easier to read for another programmer.