Performance Test: Loading CSV Versus Loading Excel In Power Query

Chris Webb lays out a performance test which shows how quickly Power Query can read data from a CSV versus from an Excel spreadsheet:

The black line in the graph above is the amount of data read (actually the offset values showing where in the file the data is read from, which is the same thing as a running total when Power Query is reading all the data) from the Excel file; the green line is the amount of data read from the CSV file (the same data shown in the first graph above). A few things to mention:

  • Running Process Monitor while this second query was refreshing had a noticeable impact on its performance – in fact it was almost 20 seconds slower

  • The initial values of 80 million bytes seem to be where data is read from the end of the Excel file. Maybe this is Power Query reading some file metadata? Anyway, it seems as though it takes 5 seconds before it starts to read the data needed by the query.

  • There’s a plateau between the 10 and 20 second mark where not much is happening; this didn’t happen consistently and may have been connected to the fact that Process Monitor was running

The results were remarkable; check them out.

Related Posts

Combining Stream Analytics And Azure ML With Power BI

Brad Llewellyn shows us how to feed Azure ML predictions into Power BI via Azure Stream Analytics: Today, we’re going to talk about combining Stream Analytics with Azure Machine Learning Studio within Power BI.  If you haven’t read the earlier posts in this series, Introduction, Getting Started with R Scripts, Clustering, Time Series Decomposition, Forecasting, Correlations, Custom R Visuals, R Scripts in Query […]

Read More

Extracting Numerical Data Points From Images

Matt Allington visualizes changes in the Gartner magic quadrant for BI tools: Today Gartner released the 2019 magic quadrant for Business Intelligence.  As expected (by me at least), Microsoft is continuing its trail blazing and now has a clear lead over Tableau in both ability to execute and completeness of vision.  I thought it would […]

Read More

Categories

August 2018
MTWTFSS
« Jul Sep »
 12345
6789101112
13141516171819
20212223242526
2728293031