1. A computer implemented method for obfuscating data in records of a data source, the method including: storing, by one or more data processors, a key value for a set of records from a source of the set of records, the set of records being partitioned into multiple sets of records based on a given field of records in the set of records; reading an original value in the given field of the record from a given one of the multiple sets of records, generating, by one or more data processors, an index value by applying the same stored key value and the read original value from that field to a deterministic mathematical function to produce the index value; applying the index value to a lookup table of predetermined obfuscation values to retrieve from the lookup table an obfuscation value; and replacing the original value in that given field of the record with the obfuscation value to obfuscate the original value of that given field; and storing, by one or more data processors, the given one of the multiple sets of records having remaining original values in fields and obfuscation values in those given fields in a data storage system, as an obfuscated set of records.