# Data Mapper Load IDs, upserts, lookups and errors

*Omnistudio Consultant Study Guide · Data Mappers · Last updated October 27, 2026 · https://www.certifyforce.com/study-guide/omnistudio-consultant/data-mappers/data-mapper-load-ids-upserts-lookups-and-errors*

How a Data Mapper Load decides between update and insert (record Id, single and multi-field Upsert Keys), which mapping settings handle nulls, lookups and linked objects, and which Load options control errors, assignment rules and value types.

- Certification: Salesforce Omnistudio Consultant
- Exam section: Data Mappers
- Study guide: https://www.certifyforce.com/study-guide/omnistudio-consultant

**Official exam objective:**

> Explain how Data Mapper Loads handle Salesforce ID mapping, upsert logic, and error management during data creation or updates.

## What the exam expects

- Explain how a record Id in the input makes a Load update instead of insert, and recommend passing the Id from the Extract to the Load.
- Recommend single or multi-field Upsert Keys, Required for Upsert, Default Value, Disabled and Lookup mappings from a stated data rule.
- Recommend link mappings to relate parent and child records in one Load.
- Choose between Ignore Errors and Rollback On Error, and explain Use Assignment Rules (including guest users) and Delete On Success.
- Keep values valid on the way in: value substitution inside the Load and Output Data Types compatible with target fields.

Key terms: **Upsert Key** (a mapped field the Load matches on to update or insert); **Required for Upsert** (a null value blocks the update); **Lookup** (query by a field value and write the result); **link mapping** (copy a field from one Load object to a related one); **Rollback On Error** (create or update nothing if errors occur).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Id in the input | The Load updates the record; no Id creates one | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Several Upsert Keys | Form one multi-field upsert key | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Multi-key match | The record must match all keys | [Omniscript Data Mapper Action Elements](https://help.salesforce.com/s/articleView?id=xcloud.os_omniscript_data_mapper_action_elements.htm&language=en_US&type=5) |
| Required for Upsert | A null value prevents the update | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Default Value | Loaded when null; omit if Required for Upsert is on | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Lookup | Queries by the field value and writes the result | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Link mapping | Copies the parent's Id into the child's field in one Load | [Multiple Related Object Loads (Link Mappings)](https://help.salesforce.com/s/articleView?id=xcloud.os_multiple_related_object_loadslink_mappings_47183.htm&language=en_US&type=5) |
| Ignore Errors | Skips only the failing steps | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Rollback On Error | Creates or updates nothing if errors occur | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Guest users | Can't trigger assignment rules | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |
| Output Data Type | Must be compatible with the target field, or the load can fail | [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5) |

## Check yourself

- Why does a Load create a record instead of updating one when its input JSON has no Id?
- When does a Load with two Upsert Key mappings update an existing record?
- When should a consultant prefer Ignore Errors over Rollback On Error on Standard Runtime?
- Which kind of user can't trigger assignment rules even when Use Assignment Rules is selected?

## Sources

- [Configure an Omnistudio Data Mapper Load](https://help.salesforce.com/s/articleView?id=sf.os_object_field_mapping_47137.htm&language=en_US&type=5)
- [Omniscript Data Mapper Action Elements](https://help.salesforce.com/s/articleView?id=xcloud.os_omniscript_data_mapper_action_elements.htm&language=en_US&type=5)
- [Create a Contact for an Existing Account](https://help.salesforce.com/s/articleView?id=xcloud.os_create_a_contact_for_an_existing_account_47333.htm&language=en_US&type=5)
- [Multiple Related Object Loads (Link Mappings)](https://help.salesforce.com/s/articleView?id=xcloud.os_multiple_related_object_loadslink_mappings_47183.htm&language=en_US&type=5)
- [Omnistudio Data Mappers](https://help.salesforce.com/s/articleView?id=xcloud.os_omnistudio_dataraptors_45587.htm&language=en_US)
- [Understanding Data Mapper Types in Omnistudio](https://trailhead.salesforce.com/content/learn/modules/omnistudio-data-mapper-fundamentals/explore-data-mapper-types)
- [Supported Features](https://help.salesforce.com/s/articleView?id=sf.os_omnistudio_and_omnistudio_for_vlocity_products_and_features_support.htm&language=en_US&type=5)
- [Create Interface Objects for a Data Mapper Load](https://help.salesforce.com/s/articleView?id=xcloud.os_standard_create_interface_objects_for_a_data_mapper_load.htm&language=en_US&type=5)
- [Omnistudio Data Mapper Output Data Types](https://help.salesforce.com/s/articleView?id=xcloud.os_dataraptor_output_data_types_47661.htm&language=en_US&type=5)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 12 linked practice questions, and unlimited timed mock exams are included with the Omnistudio Consultant pack (USD $19): https://www.certifyforce.com/practice-exams