What is model granularity mismatch?

< 1 min read

Model granularity mismatch happens when tables store data at different levels of detail.
For example, Sales fact had transaction-level rows but Targets table had monthly totals.
When we joined them directly, daily reports showed repeated target values.
This caused inflated variance calculations in Power BI visuals.
Aggregations became misleading because grains didn’t align.
We fixed it by aggregating sales to monthly level in a separate fact table.
Alternatively, we used measures instead of physical relationships.
After aligning granularity, KPI comparisons became accurate.
So all related tables must match business reporting level.

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