Power Query/M Optimisation: Getting The Maximum Value From A Column, Part 2
In part 1 of this series – which I strongly recommend you read before reading this post – I showed how removing columns from a table can make a dramatic improvement to the performance of certain...
View ArticleTables, Numbers, Immutability And Power Query Performance
Following on from my last two posts on Power Query performance, I thought I would write about another trick that can make a big difference to your query execution times. It’s actually something that...
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Hierarchical Navigation For Azure Data Lake Storage Gen2 In Power BI/Power Query
While the documentation on how to import data from Azure Data Lake Gen2 Storage into Power BI is pretty detailed, the connector (which at the time of writing is in beta) that supports this...
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Power BI And Case Sensitivity
Case sensitivity is one of the more confusing aspects of Power BI: while the Power Query engine is case sensitive, the main Power BI engine (that means datasets, relationships, DAX etc) is case...
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Why Does Power BI Query My Data Source More Than Once?
This week I was honoured to be a guest on the Guy In A Cube channel, and for my topic I decided to tackle one of life’s eternal questions: why does Power BI query my data source more than once when I...
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Troubleshooting Web Service Refresh Problems In Power BI With The Power Query...
Back in 2018 I wrote a blog post about how to troubleshoot web service refresh issues using a third party tool called Fiddler. It’s still relevant but Fiddler is a complex tool and installing it and...
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New “Diagnose Step” Power Query Feature In Power BI
One new feature that was introduced in the December 2019 release of Power BI Desktop, but which wasn’t mentioned in the release blog post, is the “Diagnose Step” button on the Tools tab of the Power...
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Visualising Power Query Diagnostics Data In A Power BI Decomposition Tree
Recently I’ve been working with the Power Query team to come up with some ways to help developers understand the data returned by the new Power Query diagnostics functionality. In this, the first of...
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An M Function To Help You Explore Power Query Diagnostics Data
Last week’s post showed an M function that took Power Query diagnostics data and formatted in a way that made it suitable for visualisation in a Power BI Decomposition Tree visual. This is great for...
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Adding Your Own Messages To Power Query Query Diagnostics
A quick point: while the Power Query Query Diagnostics functionality is relatively new, it’s based on Power BI/Power Query trace logging that has been around for a while. I’ve just realised that this...
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Understanding The “The key didn’t match any rows in the table” Error In Power...
One of the most common errors you’ll see when working with Power Query in Power BI or Excel is this: Expression.Error: The key didn’t match any rows in the table It can occur with almost any data...
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Keep The Existing Data In Your Power BI Dataset And Add New Data To It Using...
Power BI incremental refresh is a very powerful feature and now it’s available in Shared capacity (not just Premium) everyone can use it. It’s designed for scenarios where you have a data warehouse...
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Power Query Formatter
If you’ve ever used DAX Formatter to format your DAX code and wondered why there isn’t an equivalent for Power Query/M, then wonder no more: the nice people at Power Pivot Insights in Germany (read...
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Speed Up Data Refresh Performance In Power BI Desktop Using Table.View
It can sometimes be frustrating to work with slow data sources or complex Power Query queries in Power BI Desktop: you open the Power Query Editor, make some changes, click Close & Apply and then...
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Monitoring Power Query Memory Usage With Query Diagnostics In Power BI
In the April release of Power BI Desktop the Power Query Query Diagnostics feature was enhanced so that you can now return performance counter data. As the blog post says: When you run performance...
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Limit The Amount Of Data You Work With In Power BI Desktop Using Parameters...
If you’re working with large amounts of data in Power BI you may find that you have problems because: Your pbix file is very large You spend a long time waiting for refreshes to finish in Power BI...
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Optimising The Performance Of Power Query Merges In Power BI, Part 1
Merging (or, in SQL terms, joining) tables in Power Query is a common cause of refresh performance problems. I’ve often wondered whether there’s anything you can do to optimise the performance of...
View ArticleOptimising The Performance Of Power Query Merges In Power BI, Part 2
In my last post I demonstrated how the size of a table affects the performance of Power Query merge operations on non-foldable data sources in Power BI. Specifically, I showed that removing columns...
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Optimising The Performance Of Power Query Merges In Power BI, Part 3:...
In the last two posts in this series I showed how removing columns from the tables used in a Power Query merge operation can improve refresh performance. In this post I’ll show you a different trick...
View ArticleOptimising The Performance Of Power Query Merges In Power BI, Part 4:...
In the previous post in this series I showed how you can use the Table.Join function and the SortMerge algorithm to get much better performance for merge operations in Power Query – but only if your...
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