What common error should a data architect be aware of when using Data Loader for upsert operations?

When performing upsert operations using Data Loader, one common error that data architects should be vigilant about is the presence of duplicate external ID values within the same CSV file. The upsert process relies on external IDs to identify the records that need to be updated or inserted. If there are duplicate external ID values in the CSV file, Data Loader will encounter confusion as it cannot determine which record to update, resulting in an operation failure for those particular records. This issue emphasizes the importance of data integrity and uniqueness when preparing CSV files for data operations, as having a clear and distinct set of external IDs allows for smooth and predictable successful upserts.

It's essential for data architects to ensure that each external ID value is unique in the dataset to prevent this error and facilitate the accurate processing of records during upsert operations.