I am extremely new to salesforce. I read that we can mark any custom field as an ExternalID which creates an index over it. I have a use-case where I have multiple Address records which have the same value for the CustomerID field. Is it possible to create an index on CustomerID?

Basically, can ExternalID be non-unique?

1 Answer 1


An External Id doesn't have to be unique. You can have a field marked as external id, which will create an index. One caution is that if it isn't unique then you can't use that field for an Upsert.



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