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Category: Power BI

Design Concepts: Cognitive Load

Published 2017-11-28 by Kevin Feasel

Meagan Longoria explains the concept of cognitive load and how it relates to building reports:

Our first design concept is cognitive load, which comes from cognitive psychology and instructional design. Cognitive Load Theory says that when we present our audience with information, we are asking them to use brain power to process it. That brain power (aka working memory) is limited, so we need to be intentional about the information we present to them.

In order to commit information to memory and be able to recall it later, that information must go through sensory memory and working memory and then be encoded into long-term memory.

This concept drives a lot of good advice in dashboard and report design, particularly that if it does not directly help a person learn the important information you are trying to convey, it’s not worth having on the report or dashboard.

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Roll Your Own SSAS Performance Monitoring Tool

Published 2017-11-27 by Kevin Feasel

Shabnam Watson has a great post on building an Analysis Services performance monitoring tool from scratch using Power BI:

In many cases, SSAS works efficiently with default settings right out of the box. However, when you have large databases, substantial number of concurrent users, insufficient resources on your server, or when best practices are not followed during SSAS database design, you can run into performance bottlenecks and problems. In these scenarios, you need to know what to measure and how to measure them, what’s normal for your environment (benchmark), and you need to have some amount of historical measurements to be able to see the events that lead to a certain bad performance/failure point. Once you have this data, you can improve your server’s performance by addressing the problem(s).

This is a tour de force of an article, absolutely worth reading if you plan on dealing with Analysis Services at some point.  Even if you don’t build your own tool, you’ll learn a lot about what drives SSAS performance and what indicates that there might be a problem.

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Getting Distinct Dimension Count Based On A Filtered Measure

Published 2017-11-24 by Kevin Feasel

Gogula Aryalingam shows us a neat trick in Power BI:

Enthusiastic as we were, one of the hardest nuts to crack, though it seemed so simple during requirements gathering, was to perform a distinct count of a dimension based on a filtered measure on a couple of the reports. To sketch it up with some context; you have products, several more dimensions, and a whole lot of measures including one called Fulfillment (which was a calculation based on a couple of measures from two separate tables). The requirement was to get a count of all those products (that were of course filtered by other slicers on the Power BI report) wherever Fulfillment was less than 100%, i.e. the number of products that had not reached their targets.

Simple as the requirements seemed, the hardest part in getting it done, was the limited knowledge in DAX, specifically, knowing which function to use. We first tried building the data model itself, but our choice in DAX formulae, and the number of records we had (50 million+) soon saw us running out of memory in seconds on a 28GB box; Not too good, given the rest of the model didn’t even utilize more than half the memory.

Click through for the answer.

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Jitter In Power BI Charts

Published 2017-11-15 by Kevin Feasel

Rob Collie shows how to incorporate jitter in Power BI scatter charts:

Now, sometimes you may WANT multiple rows to combine into one dot, but in this particular case, I want to see each row of my source data as its own dot.

When adding a new calculated column, there are LOTS of ways to uniquely “stamp” each row with its own distinct value.  I could do this in DAX, but it would require concatenating/combining enough columns together (in this case, probably [Game #], [Qtr], and [Time], since no two rows can “happen” at the same time in the same game.

But for other reasons that you will see shortly, I need the unique identifier to be a number, and I don’t want to go through the contortions of converting text values to numeric, plus as you can see, the data is incomplete in the [Time] column (lots of blanks).

There’s a lot here, and the end result is a great addition to your Power BI toolbelt.  But as I’m reading Rob’s post, I’m thinking about how much easier it is to do some of this with ggplot2.

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Power BI Query Reduction

Published 2017-11-09 by Kevin Feasel

Wolfgang Strasser points out a new feature in Power BI Desktop:

In some cases, sources for Direct Query models are either large (and therefore need some time to bring back the data) or slow (which could maybe be improved by some database tuning :-)).

Before the Nov2017 release, every change in a filter or slicer led to an immediate round trip to the data source which made some of those reports … let’s call it .. not perfect in the context of user experience.

Beginning with the Nov2017 release some options for Query Reduction has been introduced.

Click through for an example of how to use Query Reduction on direct query models.

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Dynamic Row-Level Security And Power BI

Published 2017-11-09 by Kevin Feasel

Reza Rad shows how to build role-based filters in Power BI and use those to implement row-level security:

 

I have written while ago, about how to implement a dynamic row level security in Power BI. This post is an addition to that post. I’ve had a lot of inquiries that; “What If I want users to see their own data, and the Manager to see everything?”, or “How to add Manager or Director Level access to the dynamic row level security?” This post will answer this question. In this post, you will learn a scenario that you can implement a dynamic row level security. In this scenario, everyone will see their own data, but the manager will see everything. If you want to learn more about Power BI, read Power BI book from Rookie to Rock Star.

Read on to see one method of solving this dilemma.

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Power BI Report Server Scheduled Refresh

Published 2017-11-07 by Kevin Feasel

Wolfgang Strasser covers Power BI Report Server’s scheduled data refresh ability in a two-part series.  First, he shows how to configure scheduled data refresh:

What needs to be added here is the fact that data refresh can be speeded up to 1 minute refresh intervals. (Which is much more often compared to 8 times for powerbi.com PRO users).

When you are done with the schedule configuration, save it and the definition dialog is updated with the plan information. The last data refresh timestamp plus the last status is also displayed.

Just like Reporting Services, data refresh happens via SQL Agent job.  Wolfgang then shows us what’s in the Power BI Report Server’s metadata database:

CAUTION: The PBIRS meta-database is a system database needed for successfully running PBIRS. Do NOT modify objects in that database – a non-functioning PBIRS could be the result!

The table dbo.SubscriptionHistory contains the history of data refresh actions. A SELECT on this table provides you with the following information:

  • Subscription metadata (SubscriptionID plus Type)

  • Execution runtime information (HistoryID, StartTime, EndTime, Status plus Message)

I’m pretty jazzed about this feature.

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Using C# To Stream Data Into Power BI

Published 2017-11-06 by Kevin Feasel

Chris Koester shows us how to pass data from our .NET applications into a Power BI streaming dataset:

This post will demonstrate how to push data into Power BI Streaming Datasets with C#. For demo purposes I normally use LINQPad to run the code, but you could also create a .Net or .Net Core console application. LINQPad is an excellent, lightweight scratchpad for C# and other .Net languages.

Power BI Streaming Datasets are a very cool feature because dashboard tiles that use them update in real time. You don’t have to refresh the browser window to display new data. With this feature you can watch your data in near real-time. This could be compelling in scenarios involving sensors, IoT, website traffic, etc.

Click through for the demo script.  This shows how easy it can be to take your on-premises data and feed it into live Power BI dashboards.

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BI Announcements At PASS Summit

Published 2017-11-03 by Kevin Feasel

Chris Webb points out some good news released at PASS Summit:

Power BI Report Server

There’s a new release of Power BI Report Server available, and you can read all about it here:

https://powerbi.microsoft.com/en-us/blog/new-version-of-power-bi-report-server-now-available/

The blog post highlights the fact that you can connect to SSRS shared datasets via OData – which is basically what I was talking about here.

This is the big one for me, but there are a few other product updates that Chris covers as well.

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