What is a Cartesian join and why is it dangerous?

< 1 min read

A Cartesian join happens when tables are joined without a proper join condition.
It combines every row from one table with every row from the other table.
This can massively increase the number of records returned.
In my project, this caused performance issues during an early query test.
It also leads to incorrect and meaningless analysis results.
Cartesian joins consume high memory and processing resources.
That’s why join conditions must always be clearly defined.

Power BI Essentials