The core principle is Context Transition (current row filtering), a mechanism in analytical database theory where functions categorized as iterators or revisors modify the implicit filter context at every evaluation point during iteration, rather than operating on the current static context of the parent query scope. Formally defined within Power BI DAX architecture and Measure Theory, this rule dictates that when an iterator function processes row-by-row logic containing a Reviser (specifically CALCULATE), it induces an automatic copy and move operation of specific column values into the filter context for each step, ensuring isolated evaluation environments without external override filters. This concept relates to its parent discipline by explaining how dynamic measure calculations are scoped per-iteration rather than aggregating global results prematurely, serving as a fundamental theorem for understanding scope separation in multidimensional data modeling.
The core principle is Context Transition (current row filtering), a mechanism in analytical database theory where functions categorized as iterators or revisors modify the implicit filter context at …