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Business Platforms & EA · Foundational

External ID

Custom field flagged as containing a unique record identifier from an external system, indexed for searches and upserts.

Definition

External ID fields can be text, number, email or auto-number and are automatically indexed. They are used to upsert records and match relationships during imports without knowing Salesforce IDs. An object can have up to 25 external ID fields.

Example

ERP_Customer_Number__c is marked External ID and used to upsert Accounts nightly.

Exam tip

To prevent duplicate inserts during integration, use upsert on an External ID field.

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