Adding entries to a keyword variable in workflow manager

I need to get a total of all the amount fields, of all existing records in a file cabinet, in a workflow. I can read all of these fields into a keyword variable and then loop through the keyword variable adding each amount. (I am aware of the 100 record limit). However, keyword variables only record one entry if any of the other entries are the same.

For example, 5 documents exist in the FC. Each has an amount index field. the amounts are 100 200 300 300 400. When I read these into a keyword variable using an Assign Data task, I will get a count of only 4 records and the values will be 100, 200, 300 and 400. The 300 amount will only get written once.

Does anyone know of a way or more sophisticated approach to the problem?

Many thanks,

Hi Steve, 

is this an on-premise system? If yes, I would just use SQL to accomplish this task.
If it is a cloud system, I would probably just fire up Visual Studio to code an application or a service which does this using the .NET API.
This task seems too complicated for the limits of workflow designer - only helpful thing I can think of is using a table field with just one decimal row, then add entries to that instead of the keyword field, that way you don't have the duplicate problems.

Greetings from Germany, 
Simon H. Hellmann
DocuWare System Consultant