What is fact-to-fact relationship and why is it risky?

< 1 min read

A fact-to-fact relationship occurs when two fact tables are directly connected to each other.
For example, Sales fact linked directly with Returns fact using Product ID.
Both tables contain multiple rows per product, creating many-to-many duplication.
Totals became inflated because each sales row matched multiple return rows.
Power BI also produced ambiguous filter paths during filtering.
Performance degraded since large tables were joining repeatedly.
Instead, we connected both facts through shared dimensions like Date and Product.
Measures were calculated separately and then compared in visuals.
This avoided duplication and ensured accurate reporting numbers.

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