Query folding in Power Query in Power BI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is query folding in Power Query?

Query folding is when Power Query translates your data transformation steps into a single query that runs on the data source, like a database, to improve speed and efficiency.

beginner

Why is query folding important?

It makes data refresh faster by pushing work to the data source instead of doing it locally, saving time and computer resources.

intermediate

How can you tell if query folding is happening in Power Query?

Right-click a step in Power Query and choose 'View Native Query'. If this option is available and shows a query, folding is happening.

intermediate

Name one common action that can break query folding.

Adding an index column or using certain custom functions can stop query folding because these steps can’t be translated back to the data source.

intermediate

How can you improve query folding in your Power Query transformations?

Try to do filtering, grouping, and sorting early in the query steps and avoid transformations that Power Query can’t push to the data source.

What does query folding do in Power Query?

A Creates a backup of the query

B Runs transformations on the data source to speed up processing

C Deletes unnecessary data automatically

D Copies all data locally before transforming

Query folding pushes transformations to the data source, making processing faster.

Which step can break query folding?

A Adding an index column

B Sorting data

C Filtering rows

D Selecting columns

Adding an index column often breaks query folding because it can’t be translated to the data source.

How do you check if query folding is active for a step?

A Refresh the query

B Look for a green checkmark

C Check the data preview

D Right-click the step and select 'View Native Query'

The 'View Native Query' option shows the folded query if folding is active.

When should you apply filters to maximize query folding?

A At the end of the query

B In the middle of the query

C Early in the query steps

D Filters do not affect query folding

Applying filters early helps Power Query push them to the data source.

What is a benefit of query folding?

A Reduces load on your computer

B Slows down data refresh

C Uses more local memory

D Prevents data refresh

Query folding reduces local processing by using the data source to do work.

Explain what query folding is and why it matters in Power Query.

Think about how Power Query talks to databases to save time.

Describe how you can check if query folding is working and what can cause it to stop.

Look for the native query and think about complex steps.