- the process variable fields for each variable types are merged into one field
- the variable value field becomes a multi field similar to the decision variable value field
- the upgrade script is adjusted so that all process variables are transformed to the new structure
Currently, we import the process variables to the process instance index. Each variable is added as a separate variable field. For the decision variables we already tried out a new version where each variable is multi field. We should make that consistent and do it for the process variables as well. The benefit would be that the whole code around the variables becomes way simpler. Downside if this refactoring would include a lot of work in the upgrade script.