Operator: UnionByKey

• This operator is used in the following Steps:
  
  87 UnionByKey of Case Churn Prediction Case
  Vereinigung (1) of Case LifeInsuranceChurnPrediction
  Vereinigung (2) of Case LifeInsuranceChurnPrediction
  Vereinigung der Vertraege mit und ohne Rueckkauf of Case LifeInsuranceChurnPrediction
  Vereinigung (3) of Case LifeInsuranceChurnPrediction
  Join the decision attribute sources (union) of Case Call Center Case - NIT
  Join statistics and decision attribute source (union) of Case Call Center Case - NIT