Upsert
One integration operation that creates a missing record or updates the existing one matched by a stable external ID.
See it
What it is
In an integration, an upsert means 'find this record by a stable key, update it if found, otherwise create it.' Salesforce supports this with External ID fields, so a connector can send the same account again without first asking whether that account already exists. It replaces a read-then-branch dance with one operation.
Reach for it in imports and recurring syncs where the source has a durable identifier. Store that source ID in a unique destination field and make it the match key. Email addresses, names, and phone numbers change and collide, so they are poor identities even when they look convenient.
An upsert prevents duplicate records; it does not decide whether an incoming value deserves to win. A late event can overwrite newer data, and a source can blank fields owned by the destination. Pair the write with explicit field ownership plus a version or source timestamp, and define whether omitted fields mean 'leave unchanged' or 'clear this value.'
Ask AI for it
Implement Salesforce Account upserts through the REST API using a custom External ID field named Source_Account_ID__c. Send PATCH requests to the sObject external-ID resource so the same source record creates once and updates thereafter, and keep Source_Account_ID__c unique. Map only the fields this connector owns, treat omitted fields as unchanged, reject records with no source ID, and compare SystemModstamp before accepting a late write. Add tests for create, update, repeated identical input, duplicate external IDs, and an older update arriving last.