Table.TransformColumnNames(PreviousStep, Text.Lower)

[Daniell1]

I have two sources (Dierct Queries) in Power BI, which I want to use interchangably. All column names in the first source are written in lower case, while in the other one the same tables and column names are written in the Upper Case. I found that I can use Table.TransformColumnNames(PreviousStep, Text.Lower) to lower the the letters in the second source. My question is how it impacts the performance?

[v-karpurapud · Accepted solution]

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.

If my response has resolved your query, please mark it as the Accepted Solution to assist others. Additionally, a 'Kudos' would be appreciated if you found my response helpful.

Thank you!

[GilbertQ]

Hi @Daniell1 

As always, this depends on the data source that you are connecting to. And the only way I can recommend knowing what the impact will be to performance is is to try it out and measure the performance to see how it will change.