A method includes receiving a plurality of data sets. Each data set includes a customer identifier field specifying a unique customer identifier associated with each entry in each data set. The plurality of data sets includes a first group of data sets and a second group of data sets. The method further includes storing the plurality of data sets, and generating a key map including the customer identifier field including unique customer identifiers of the first group of data sets of the plurality of data sets, and an anonymous identifier field including unique anonymous identifiers. Each anonymous identifier corresponds to a customer identifier of the key map. The method further includes replacing each unique customer identifier in the second group of data sets with the corresponding anonymous identifier.