I want to check records during list import to see if they’re already in my data target. Should I use De-duplication and Merge, De-duplication and Merge against Master, or the Infer task?

The task to use depends on your situation and the results you want to achieve. The following guidelines may be helpful:

• If you do not want to merge any data, then use the Infer task.
• If you are looking for duplicates within your import list, use the De-duplication and Merge task.
• If you are looking for duplicates in another data source (ie. Salesforce, Marketo, etc.) AND want to merge data, then use the De-duplication and Merge against Master Data task.

If you use either the De-duplication and Merge task or the De-duplication and Merge against Master Data task, your output data set from the task will include new attributes you can use to determine which records are the Surviving records and which are the duplicates. See the individual task help pages for details on using these fields.