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Category: Power BI

Query Folding and the Power BI Dataflows Enhanced Compute Engine

Matthew Roche dives into Power BI’s enhanced compute engine:

I’ve been seeing more questions lately about the dataflows enhanced compute engine in Power BI. Although I published a video overview and although there is feature coverage in the Power BI documentation, there are a few questions that I haven’t seen readily answered online.

A lot of these questions can be phrased as “what happens when I turn on the enhanced compute engine for my Power BI Premium capacity?”

Most of my responses start with the phrase “it depends” – so let’s look at some of the factors the answer depends on.

Click through for those factors.

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Splitting a Power BI Report into a Golden Dataset and a Thin Report

Imke Feldmann walks us through separating data from report in Power BI:

The other day I discovered a neat way to split up an existing Power BI report into a Golden Dataset and a thin report file with very few adjustments to the existing setup. Imagine you have a Power BI report published for some time already in an app with row level security. Now, you want to create other reports from the dataset as well and decide it’s time to create a golden dataset from which multiple other thin reports can also be fed from as well. But ideally you want to keep your published app, that many users are working with already, unchanged.

There’s a way to do this and Imke shows us the way.

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Automating Power BI Deployments

Martin Schoombee has started a series on automating Power BI deployments. The first post covers some of the basics of Powershell:

The console works great when you’re executing single commands, but not when you’re developing entire scripts. The ISE has a built-in console and has everything you need from a development perspective.

I have recently started using Visual Studio Code to develop my PowerShell scripts, and it works pretty well and feels like a more complete development tool. You would also need to use VS Code if you want to install and use PowerShell 7, because it doesn’t work with the ISE. I don’t want to get too lengthy here, so if you’re interested in using VS Code you can read all about it here.

Click through for the entire article.

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Choosing a Power BI Report Type

Paul Turley compares Power BI paginated and analytic reports:

This brings me to the subject of this post: Paginated and Analytic reports.

Before we had Power BI, we had Reporting Services. When the focus of my career and consulting practice became Business Intelligence – fifteen to about five years ago – most of the “BI reports” I created were in SQL Server Reporting Services (SSRS). We could create a variety of charts and reports that allowed users to drill-down from summary to details. We could create reports that allowed a user to drill-through, from one record or report item to another report that presented more details. With a little creativity, we could create reports that allowed users to click items that would filter other items on the same report. It took some work and time to create these interactive “drill-through-to-self” reports. Today, after transforming data into the right format for a tabular data model, this type of interactive functionality just magically happens in Power BI with very little report design effort. But, Power BI is primarily a tool for analyst users to create their own reports and to get answers to business questions rather than for IT developers to create reports that print or export perfectly to a PDF or Excel.

For now, Paul is asking for thoughts and questions with the promise that there will be an update to the post. So stop on by and ask a question or two.

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Power BI (Lack of) Performance with Sharepoint

Matt Allington is not impressed:

On the face of it, it seems like a great idea to leverage SharePoint as a storage location for CSV and Excel files.

– Everyone has easy access to the files for editing and storage
– SharePoint manages version control, check in, check out etc
– SharePoint can facilitate shared editing of files
– You can build a Power BI report that will refresh online without the need to install a gateway.

Unfortunately, despite the benefits, the experience is not great.  Power BI performance with SharePoint as a data source is simply terrible.  Ultimately, the problems come down to performance in 2 areas.

Read on to learn more about these two issues and what you can do instead.

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Finding the earliest and latest date across all Power BI Tables

Soheil Bakhshi has an interesting challenge:

Many of you may already thought that we can use CALENDARAUTO() in DAX and we are good to go. Well, that’s not quite right. In many cases there are some Date or DateTime columns that must not be considered in our Date dimension. Like Birth Date or Deceased Date. More on this later in this post.

In this post I share a piece of code I wrote for myself. I was in a situation to identify the Start Date and the End Date of the date dimension many times, so I thought it might help you as well.

Read on for a solution when not all date columns are relevant.

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Conditional Merges in Power Query

Ed Hansberry shows how to perform a conditional join in Power Query:

I am going to use two tables for this example, Fact.Sales and Dim.Customer. I only want my Fact Sales table to have customer info for the Buying Group Tailspin Toys. That info is in the Dim Customer table. I can do this several ways.

1. Do the merge, expand the Buying Group column from the Customer table, then filter to only show those rows.
2. Pre-filter the Customer table for Tailspin Toys in the Buying Group column, then do the merge. It would need to be an Inner Join, otherwise you will get nulls in the Sales table when you expand, and then you have to filter those out. Which you can do, but it is more steps.
3. You can bypass all of that and do it in one step.

I’m not going to bore you with how to do methods 1 and 2. Let’s do method 3, a conditional join!

Read on for the approach, which also can take advantage of query folding when possible.

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Automatic Retention Periods with Power Query

Gilbert Quevauvilliers has an easy method of constraining data sizes in Power Query:

How cool would it be to not have to manually update your dataset to keep data for last 2 Years (last year and this year to the current date)?

In this blog post I will show you how you can easily filter dates in Power Query to show dates for last year and year to date by using the GUI and not having to hardcode anything.

I must admit the first time I saw this was when I watching my good friend Reid Havens presenting. Thanks Reid!

Read on for the technique.

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Optimizing Cross Join Performance in Power BI

Chris Webb tries an experiment:

In a late addition to the series of posts that I started here a few months ago, I thought it would be useful to look at how to optimise the performance of a rare (but nonetheless useful) type of merge: the cross join. Cross joins are not available as a join kind in the Table.Join or Table.NestedJoin M functions but there are two ways of creating them in Power Query:

1. Creating a custom column in your query that contains the query that you want to cross join with and then expanding, as Matt Allington describes here
2. Creating a custom column that contains a single value, such as the number 1, on both your queries and then using that column to merge the two queries on (something I mentioned a long time ago here)

Which one gives you the best performance? 

Chris has the answer to that question and the tests to prove it.

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Power BI Migration Documentation

Melissa Coates announces some new documentation:

I’m really pleased to announce that new Power BI Migration documentation that I authored is published on the Microsoft Docs site. Although it was written from the perspective of migrating to Power BI from another platform, there’s no doubt that a lot of the content applies to a standard Power BI implementation project.

Click through to learn more and follow Melissa’s link to get the whole document.

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