What is preview data vs loaded data in Power BI?

< 1 min read

Preview data is the sample data shown inside Power Query editor.
Power BI only displays top rows to help validate transformations quickly.
It does not represent the full dataset from the source.
In my project, preview showed 1,000 rows while source had 5 million records.
Loaded data is the complete dataset imported into the Power BI model.
This happens only after clicking “Close & Apply”.
Performance during preview is faster because it is not full extraction.
Sometimes errors appear only after load since full data gets processed.
We always validated data types before loading to avoid refresh failures.
So preview is for development checking, loaded data is actual reporting dataset.

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