What is cardinality and its impact on model performance?

< 1 min read

Cardinality refers to the uniqueness of values in a column, like Customer ID vs Country.
High-cardinality columns have many unique values, while low-cardinality columns have few.
In one project, using Customer ID in a large fact table increased memory usage and slowed DAX calculations.
High-cardinality columns also increase compression size in the VertiPaq engine.
Relationships on high-cardinality columns can slow filtering and aggregations.
Low-cardinality columns compress better and improve query performance.
We optimized by avoiding unnecessary high-cardinality columns in visuals and measures.
So cardinality affects memory, refresh, and report responsiveness.

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