Table.TransformColumnNames(PreviousStep, Text.Lower)

Hello Daniell1 

Thank you GilbertQ for your prompt response!

Thank you for contacting the Microsoft Fabric community. We understand you are looking for insights into the performance impact of the Table.TransformColumnNames transformation in Power BI.

Using Table.TransformColumnNames(PreviousStep, Text.Lower) to standardize column names across two data sources typically has minimal performance impact. As this transformation is applied at the Power Query level, it does not create additional database queries. The process is limited to renaming column headers, making it lightweight compared to more complex transformations like merging or aggregating data.

However, in scenarios where the query is complex or the transformation is combined with multiple steps, Power BI may generate additional SQL queries to rename columns before executing the main query. This can potentially increase query execution time, especially when dealing with large datasets or when multiple transformations are applied sequentially.

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