What methods can be employed to avoid duplicate contacts during the migration of contacts into the Salesforce org?

Creating a new text field to contain a hashed value for (first name+last name + street number) and defining it as an External ID is an effective strategy to avoid duplicate contacts during the migration into Salesforce. This method offers several advantages.

Firstly, by generating a hashed value, you create a unique identifier for each contact based on their name and street number combination. Hashing is a robust approach because it converts these values into a fixed-length string that represents the original input in a way that is generally consistent for the same input values. This means that when two contacts have the same name and street number, they will generate the same hashed value, making it easy to identify duplicates before migration.

Defining this field as an External ID adds further capability by allowing Salesforce to automatically enforce uniqueness for the records being migrated. When importing contacts, Salesforce can check the hashed External ID field against existing records to prevent the creation of duplicates in real-time.

It’s important to note that using an indexed formula field or a simple formula field, while helpful for searching and reporting, does not provide the same level of uniqueness control that an External ID does. Indexed fields can improve search performance but do not inherently manage duplicates during data import. After the fact, using a third-party