Power BI includes a feature called Autodetect new relationships that automatically creates relationships between tables when new data is loaded into a model. While convenient for simple datasets, this setting can cause unexpected behavior in more advanced data models.

How to Turn Off Autodetect New Relationships

You can disable this feature directly from Power BI Desktop:

1. Open Power BI Desktop
2. Go to File → Options and settings → Options
3. In the left pane, under CURRENT FILE, select Data Load
4. Then in the page’s main area, under the Relationships section, uncheck:
   • Autodetect new relationships after data is loaded
5. Click OK

Note that you may need to refresh your model for the change to fully take effect on newly loaded data.

Why You May Want to Disable This Feature

Turning off automatic relationship detection is considered a best practice for many professional Power BI models, especially as complexity increases.

Key reasons to disable it include:

• Prevent unintended relationships
  This is the main reason. Power BI may create relationships you did not intend, based solely on matching column names or data types. Automatically generated relationships can introduce ambiguity and inactive relationships, leading to incorrect DAX results or performance issues.
• Maintain full control of the data model, especially when the model needs to be carefully designed because of complexity or other reasons
  Manually creating relationships ensures they follow your star schema design and business logic. Complex models with role-playing dimensions, bridge tables, or composite models benefit from intentional, not automatic, relationships.
• Improve model reliability and maintainability
  Explicit relationships make your model easier to understand, document, and troubleshoot.

When Autodetect Can Still Be Useful

Autodetect is a useful feature in some cases. For quick prototypes, small datasets, or ad-hoc analysis, automatic relationship detection can save time. However, once a model moves toward production or supports business-critical reporting, manual control is strongly recommended.

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