11.34Parent-child bulk load

Suppose you need:

100,000 Accounts
500,000 Contacts

Contacts need Account relationships.

One strategy:

1. Bulk upsert Accounts

2. obtain / correlate Account IDs

3. transform Contacts

4. Bulk upsert Contacts

But this can be simplified if Salesforce external-ID relationships fit your schema.

Either way, load ordering and relationship resolution matter.