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Category: Power BI

Incremental Refresh on Large Power BI Semantic Models

Published 2024-03-12 by Kevin Feasel

Soheil Bakhshi needs to refresh a lot of data:

Implementing incremental refresh on Power BI is usually straightforward if we carefully follow the implementation steps. However in some real-world scenarios, following the implementation steps is not enough. In different parts of my latest book, Expert Data Modeling with Power BI, 2’nd Edition, I emphasis the fact that understanding business requirements is the key to every single development project and data modelling is no different. Let me explain it more in the context of incremental data refresh implementation.

Read on for that explanation, as well as a few tips to make things work a bit more smoothly.

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VISUAL SHAPE and Visual Calculations

Published 2024-03-12 by Kevin Feasel

Marco Russo and Alberto Ferrari fit the square pegs into the square holes:

Visual calculations, introduced as a preview feature with the February 2024 release of Power BI, aim to simplify the creation of calculations tied to a specific visual. Using visual calculations for simple calculations is straightforward.

However, as soon as developers create more complex calculations, they should understand the technical details of visual calculation implementation. This requires understanding the hierarchical structure of the virtual table, the new visual context, the semantics of ROWS and COLUMNS, the behavior of CALCULATE, and the new visual context modifiers EXPAND and COLLAPSE.

In this first article about visual calculations, we introduce VISUAL SHAPE and the basics of visual calculation implementation, leaving the remaining topics to future articles. A complete whitepaper with a detailed explanation of all these topics will be available soon to SQLBI+ subscribers.

Even without a complete whitepaper, this serves as a useful primer on the topic.

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Relationship Columns and Power BI DirectQuery Mode

Published 2024-03-11 by Kevin Feasel

Chris Webb builds a relationship:

Many Power BI connectors for relational databases, such as the SQL Server connector, have an advanced option to control whether relationship columns are returned or not. By default this option is on. Returning these relationship columns adds a small overhead to the time taken to open a connection to a data source and so, for Power BI DirectQuery semantic models, turning this option off can improve report performance slightly.

Read on to learn what these relationship columns are and how you can remove them. Chris also provides a first-order approach to how you can estimate the performance pain involved with including these.

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Improving Data Labels with Format Strings

Published 2024-03-06 by Kevin Feasel

Kurt Buhler has some new digs:

Format strings greatly improve the usefulness of your model, particularly when you apply custom and dynamic format strings creatively. However, there are considerations to keep in mind.

It is important that the values in a report display for users as they expect. Effective formatting of DAX measures and table columns improves your model, as values are easier to read and interpret. While formatting may seem simple at first glance, the flexibility of DAX and format strings in Power BI can create many opportunities for more creative and efficient tables or visuals.

Click through to understand why proper formatting of measures is so important on dashboards, and also congratulate Kurt on becoming an Italian. At least, I assume citizenship conveys when you do work for Marco & Alberto.

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Measuring Query Times in Power BI DirectQuery Mode

Published 2024-03-05 by Kevin Feasel

Chris Webb breaks out the stopwatch:

If you’re tuning a DirectQuery semantic model in Power BI one of the most important things you need to measure is the total amount of time spent querying your data source(s). Now that the queries Power BI generates to get data from your source can be run in parallel it means you can’t just sum up the durations of the individual queries sent to get the end-to-end duration. The good news is that there are new traces event available in Log Analytics (though not in Profiler at the time of writing) which solves this problem.

Read on to learn more about this event.

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Reducing Power BI Dataset Sizes with Semantic Link

Published 2024-03-04 by Kevin Feasel

Sandeep Pawar builds some really cool diagnostics:

Semantic Link v0.6 is out and it has many new exciting additions to its growing list of list_* methods. Highlighted are some of the new methods. Install the latest version and check it out.

Some of the existing methods such as list_columns() have an additional parameter extended which returns more column information such as column cardinality, size, encoding and many more column properties. This allows users to get detailed information about the dataset and the columns.

Click through to see how you can get this information not just for a single semantic model, but for all semantic models in a tenant.

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Dynamic Subscriptions in Power BI

Published 2024-03-01 by Kevin Feasel

Reza Rad sends an e-mail:

If you ever want to have a general report for sales for all countries, and then you want every morning the report to be sent (as PDF or PowerPoint alongside the link to the report) to representatives of each country, the report with the data filtered for their country only, then Dynamic Subscription in Power BI is the feature you need to use. Previously, this was called a Data-Driven Subscription in SSRS (SQL Server Reporting Services). In this article and video, I’ll explain how to use this feature using an example and what you need to know about it.

Click through for the video and blog post.

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Microsoft Fabric and Semantic Models

Published 2024-03-01 by Kevin Feasel

Kurt Buhler has a choose-your-own-adventure story:

Semantic models are integral to Microsoft Fabric. They use and are used by many of the different workloads. In Fabric, there’s more items that can connect to and consume your model—such as semantic link in notebooks. Because of these new options and tools, your model is exposed to additional types of users who will use it in different ways. As such, it’s important that you make good models that you manage well throughout their entire lifecycle.

Read on for more information and three separate scenarios

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An Overview of DAX Visual Calculations

Published 2024-02-29 by Kevin Feasel

Teo Lachev takes us through visual calculations in DAX:

Suppose you need a measure that calculates the difference between the product categories in the order they were sorted in the visual. Implementing this as a regular DAX measure is a challenge. Yet, if we had a way to work with the cells in the visual, we can easily find a way to get this to work. Ideally, this would work similar in Excel, but DAX doesn’t know a think about cell references. However, visual calculations do.

As always, Teo gives us a view of the good, the bad, and the ugly with this feature.

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dataConvergeDefinition and DirectQuery Partitions

Published 2024-02-26 by Kevin Feasel

Chris Webb talks about hybrid tables:

Hybrid tables – tables which contain both Import mode and DirectQuery mode partitions to hold data from different time periods – have been around for a while. They are useful in cases where your historic data doesn’t change but your most recent data changes very frequently and you need to reflect those changes in your reports; you can also have “reverse hybrid tables” where the latest data is in Import mode but your historic data (which may not be queried often but still needs to be available) is in DirectQuery mode. Up to now they had a problem though: even when you were querying data that was in the Import mode partition, Power BI still sent a SQL query to the DirectQuery partition and that could hurt performance. That problem is now solved with the new dataCoverageDefinition property on the DirectQuery partition.

Read on to see what dataCoverageDefinition does.

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