In Power Query, which transformation is known to break query folding when splitting a column either by position or delimiter?

• A. Add Custom Column
• B. Group By
• C. Split Column by position
• D. Filter Rows

Answer: (C)

Query folding pushes as much work as possible back to the data source, so the source does the heavy lifting. Splitting a column into multiple pieces, whether by position or by delimiter, is a shaping step that typically can’t be translated into a universal, foldable operation for many data sources. Because of that, Power Query often can’t push this split back to the source, and the subsequent steps have to run locally after the data is loaded. That’s why this transformation is known to break query folding in the scenario of splitting a column.

Other operations like adding a custom column, grouping, or filtering can sometimes be pushed to the source depending on the data source and the exact operation, so they’re more likely to remain folded in many cases.