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When do CustomerIds change?

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I wanted to  confirm the behavior of CustomerIds generated for each record. My understanding is that these are a hash of whatever the field you use as a PrimaryKey is.  If merge rules change and two existing records are conflated, a new CustomerId is generated.  

But what I was hoping to confirm is... assume that a record had a CustomerId generated.  The underlying record key has not changed.  In that case, the existing Customerid should be permanent unless the underlying record's key changes.  Correct?
The specific case is we have an integration with a marketing system that needs an external_id. They suggest that you use an unchanging value that uniquely identifies the record.  Was thinking CustomerId would be appropriate but wanted to make sure beforehand.  Is my understanding correct?
  • Verified answer
    Leah Ju Profile Picture
    Leah Ju on at
    When do CustomerIds change?
    Hi ,
    I found the following Microsoft documentation:
    When unification runs, a unique CustomerId is assigned to each customer profile. This ID doesn't change between unification runs except in the following two cases: Merge profiles and Split a profile

    I hope you can mark my answer verified if it is helpful! If you have any questions, please feel free to contact me.

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