Data 360: Impact of Relationships on Custom Field Definition Limits in Data Model Objects

Salesforce Data 360 (formerly Data Cloud) uses Data Model Objects (DMOs) to represent entities like individuals, accounts, or custom objects. These are connected through relationships, which define how data from one DMO relates to another.

As detailed in Data 360 Limits and Guidelines, there is a hard limit of 1,050 fields per data model object. Each outbound relationship (from the source DMO to a target DMO) creates a custom field definition on the source DMO that contributes to this limit. Custom fields include both explicitly created fields and those generated by relationships, such as those from activations or Calculated Insights (CIs).

This limit is critical in scenarios involving activations or CIs, particularly when using Data 360 Loyalty as the activation target. For example:

• Selecting New Data 360 Object during a Data 360 Loyalty activation creates a new curated DMO and establishes relationships, adding custom fields to the source DMO (e.g., BMG_AccountContact__dlm).
• Creating a Calculated Insight (CI) that references a source DMO can generate additional relationships, each adding to the custom field count on the source DMO.
• High-volume usage, such as creating multiple activations or CIs per quarter (e.g., over 200 campaigns), can accumulate relationships, pushing the DMO beyond the 1050 custom field limit.

When the limit is exceeded, attempts to create or save activations fail with errors like "Unable to create lookup for relationship" or "CustomFieldLimitExceededException" (Error ID: CustomFieldLimitExceededException). No warnings appear in the UI until the limit is hit, and the backend custom field count may not be visible in the standard object limits view. A work item is under investigation to improve UI error messaging.

Note: Inbound relationships (to the DMO) do not contribute to the custom field count on that DMO. A planned fix aims to reverse the relationship direction for Loyalty activations, reducing the impact on the source DMO’s custom field limit. For more on DMO relationships, see Data Model Object Relationships.