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Category: Power BI

Figuring Dataflow Boundaries

Published 2019-10-08 by Kevin Feasel

Matthew Roche gives some advice on how large to make artifacts in Power BI dataflows:

This post started as a response to this question from Mark, who was commenting on last week’s data lineage post:

How would you decide how big or how small to make each artifact in the lineage, in terms of the amount of transformations taking place inside the artifact? In my case they would only be shared with 2-3 other users.
For instance I could go all out and have every step that would previously take place in a query editor result in a new link in the data lineage chain, but that would probably be overkill.

I agree that “one step per dataflow” would be overkill, but beyond that the answer is largely “it depends.”

Read on to see on which factors it depends.

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Dynamically Controlling Power Query Columns

Published 2019-10-07 by Kevin Feasel

Erik Svensen wants to display columns dynamically in Power Query:

This means that even though we might add new columns to the ProductsAttributes table – it will still only be Brand that is expanded and only that column.

The bolded arguments is 2 lists that contains the Column names to expand and the new names of the columns – the last argument is optional so we can actually skip that if we want the original names – https://docs.microsoft.com/en-us/powerquery-m/table-expandtablecolumn

Read on to see how to do this.

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Power BI and Case Sensitivity

Published 2019-10-07 by Kevin Feasel

Chris Webb explains that Power BI is case sensitive except where it isn’t:

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 insensitive. Imke Feldmann shows how to make Power Query case insensitive through custom M here; in this blog post I’m going to concentrate on what case insensitivity means in datasets and DAX and show a way to (kind of) work around it.

Read the whole thing. Chris has a lot of great information here.

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Multi-Parent Hierarchies in Power BI

Published 2019-10-04 by Kevin Feasel

Imke Feldmann has another way to solve the multi-parent problem in Power BI:

If you have parent-child-hierarchy with multiple parents, my function will a table like below, where the children with multiple parents still reside in different rows:

Due to this, the table cannot directly be connected with the FactTable, as NodeKey is not unique. Solution is to create DimNode-table that contains only unique values from the NodeKeys. Use it as a bridge between the 2 tables and implement a bidirectional filter to the Nodes-table:

Read on for the complete answer and to grab a copy of the PBIX file.

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Power BI Column Concatenation

Published 2019-10-04 by Kevin Feasel

Alexander Arvidsson shows how we can concatenate columns in Power BI using DAX:

Finally we can tackle the last hurdle – the column that shows both the current number of certifications and the requested goal. Had this been Excel it would have been dead easy – we just create a new cell that concatenates two other cells like this:

Then we copy the formula to all the rows. Easy. But this is not Excel. The “goal” part is simple – that’s just another column. The trick is to count all the other rows in the table with the same key. Let’s add the key column to the table so we see what we’re working with. “CompKey” is the concatenated key we created in the previous blog post. “Number of certs” is a count of the rows in the table, and because of row context it gets evaluated per key.

Read on for the solution.

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Query Folding, Azure DevOps, and Power BI

Published 2019-10-02 by Kevin Feasel

Eugene Meidinger tries to work around a query folding limitation:

Query folding is one of the most powerful tools in Power Query and Power BI. It is the automatic process of pushing down filters and other transformations back to the data source. This can dramatically improve performance for your queries.

Unfortunately, OData is not guaranteed to support query folding. According to the Power BI documentation on incremental refresh.

Click through for Eugene’s alternative solution.

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REMOVEFILTERS() in DAX

Published 2019-10-02 by Kevin Feasel

Matt Allington takes us through the REMOVEFILTERS() function in DAX:

Recently Microsoft introduced a new function in DAX called REMOVEFILTERS(). This is a very useful and well named function and it does exactly what its name suggests. Its purpose is to act as a table filter parameter inside CALCULATE() as shown in the following example.

Total Sales All Products REMOVEFILTERS() = CALCULATE([Total Sales],REMOVEFILTERS(Products))

Read on to see how this compares to the prior/alternative solution and for more information on REMOVEFILTERS().

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Power BI Performance Tuning

Published 2019-10-01 by Kevin Feasel

Eugene Meidinger gives us a detailed guide to Power BI performance tuning:

As a report developer, it can be frustrating a report developer, knowing that something is slow, but not being able to put your finger on it. In my mind, there are 4 main areas where there might be a slowdown:

1. Data refresh
2. Model calculations
3. Visualization rendering
4. Everything else

Identifying which one of these is the problem is the first step to improving performance. In most cases, if a report is slow it’s an issue with step 2, your data model.

Eugene has plenty of good advice here.

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ADLS Gen2 Navigation in Power Query

Published 2019-10-01 by Kevin Feasel

Chris Webb shows off hierarchical navigation in Power Query against Azure Data Lake Storage Gen2:

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 functionality in the Power Query engine has some useful functionality that isn’t so obvious. If you look at the built-in documentation on the AzureStorage.DataLake M function in the Power Query Editor you’ll see there are a lot of options that aren’t in the documentation on the web yet:

Click through for an example.

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Using the Power BI API

Published 2019-09-30 by Kevin Feasel

Jeff Pries takes us through the Power BI API with Powershell:

The Power BI API is a way of essentially bypassing the web interface of powerbi.com and asking questions directly to the back-end of the service (without bypassing security). Using this allows you to issue a command, such as “Give me a list of all of the workspaces” and receive just the result data in a bulk data format. While outside the scope of this exercise, the API also allows reading actual business data from Power BI assets and even manipulating assets.

For my first attempt at interacting with the API, I decided to try the Microsoft developed Powershell Cmdlets. These are a set of free Powershell commands which can be installed on your workstation and then will query the Power BI API and return results in a standard way without the need to write any code (C# or otherwise) or understand how to read a JSON response.

Jeff does more than just hit API endpoints, though, so read the whole thing.

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