In DAX theory, aggregate iterator functions (e.g., SUM) function syntactically as shortcuts that implicitly derive a temporary virtual table from the current filter context before executing their aggregation logic on the resulting expression column. The abstract mechanism defines these operations not as direct evaluations of physical source tables but as two-step processes: first generating visible rows based on contextual filters, then iterating over derived columns to compute results like sum or maximum. This distinction is critical for understanding DAX's execution model where code readability and error diagnosis depend on explicitly recognizing hidden derivation steps rather than relying on the semantic intent suggested by short-form syntax.
In DAX theory, aggregate iterator functions (e.g., SUM) function syntactically as shortcuts that implicitly derive a temporary virtual table from the current filter context before executing their agg…