Get all lucene values that have a certain fieldName

To solve this problem I created a new Lucene index where all possible distincted values of each field are indexed seperatly.

So it's an index with a few thousand docs that have a single Term.
I want to extract all the values for a certain term. For example, I would like all values that have the fieldName "companyName".
Defining a WildcardQuery is off course not a solution. Neither is enumerating ALL fields and only saving the ones with the correct fieldName.

From stackoverflow

• This should work (I take it it still is in C#)

  IndexReader.Open(/* path to index */).Terms(new Term("companyName", String.Empty));
  

  borisCallens : ah, empty string :) (added C# tag)