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In this blog series, we’ll explore some easy ways to reduce the size of a Power BI model.

Our previous blog posts:

The impact of a column

Power BI isn’t just a database. The way in which Power BI saves data works differently from a ‘normal’ database, such as SQL or Access. In Power BI, data are stored and analysed in columns. In other words: the more columns, the more data Power BI needs to analyse. And the more unique values in a column, the longer it takes to analyse said column.

This is why it’s a good idea to only load the columns you really need in a model. This way the model will be smaller and more responsive.

The following columns aren’t needed in my report, so I’ll remove them from my model:

  • InvoiceDate, ShippingDate (in Sales)
  • Week or Weekend, Semester (in Dates)

After refreshing the data in Excel, you’ll see that the model has dropped from 18 MB to 16.8 MB.

This does not look like a big difference but in this example the table only consists of 260.000 records.

There is also one extra field that should be deleted, but this will be explained in the next blogpost.: because you understand the impact of deleting columns better


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