Salesforce Lookup vs. Master-Detail Relationships

Salesforce lookup and master-detail are two ways to relate records, but they create different levels of dependency. A lookup is generally a looser relationship; master-detail makes the child record dependent on its parent and enables native roll-up summaries. Choose based on the data model and lifecycle you need.

Lookup relationships keep records more independent

A lookup connects one record to another without making the child fully dependent on the parent. The relationship can be optional or required depending on configuration, and child ownership and sharing are generally managed separately, subject to the object’s sharing settings.

Lookup is useful when both records have independent lifecycles—for example, a task or asset that should remain meaningful if a related record changes. Before allowing parent deletion, decide whether the reference should be cleared or deletion should be blocked.

• Use when the child can exist independently.
• Review lookup behavior when the referenced record is deleted.
• Check sharing and ownership settings separately.

Master-detail makes the child dependent

In a master-detail relationship, the detail record depends on a master record. The parent relationship is required, and the child’s access and ownership behavior follows the master record’s rules. Deleting the master can cascade to detail records, so this choice has data-retention consequences.

Master-detail also supports native roll-up summary fields on the master. That can simplify totals and counts, but it makes the relationship more structural than a simple reference.

• Use when the child has no useful lifecycle outside its parent.
• Confirm cascade deletion and sharing implications with stakeholders.
• Use roll-ups only for fields that match the relationship’s purpose.

Model for lifecycle, reporting, and access

Ask what should happen if a parent is deleted, who should own the child, and whether the parent needs aggregated values. Test those cases in a sandbox with realistic data before migrating relationships.

Changing an existing relationship type can have effects on required fields, automation, reports, and access. Document the decision and verify dependent flows, integrations, and validation rules before deployment.

A line item whose value is meaningless without its invoice may fit master-detail; a vendor contact that remains useful if an account relationship changes may fit lookup. These examples are starting points only—the organization’s deletion, ownership, and access requirements should decide the model.