Power Query

  • Lazy Evaluation & Query Folding in Power BI / Power Query

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    How do things work in the world? Humans are curious beings.

    We want to know how things work and perhaps harness them for our own purposes.

    In this case, we’re curious about how the Evaluation Model works for Power BI & Power Query when it comes to executing your queries and getting your data.

    You can read the official documentation from the Microsoft team here, but in this post I’ll cover the basics, so you can have a quick overview of how things work with Power Query / Power BI and how you can optimize your queries to better harness their engine.

  • Data Privacy and the Formula Firewall in Power BI / Power Query

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    Have you ever received any Errors similar to these?

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    Formula.Firewall: Query ‘Merge1’ (step ‘Source’) is accessing data sources that have privacy levels which cannot be used together. Please rebuild this data combination.

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    Formula.Firewall: Query ‘Query1’ (step ‘Added Custom’) references other queries or steps, so it may not directly access a data source. Please rebuild this data combination.

    This is the blog post where I’ll cover this specific topic to answer 3 questions:

    • WHY does it even exist
    • What triggers this error
    • How to better spot the cause of the error

    Before we start…let’s define one concept / feature:

  • Parameter Tables in Power BI / Power Query

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    One of the most interesting and most unique scenarios is Parameter Tables in Power Query / Power BI.

    The way to make a dynamic Power Query solution is to make sure that it can be easily customizable and, at the same time, be able to work as more of a pattern rather than just a unique one off solution to a single file, table or whatever it is that your query works against. This is exactly where Parameters and Parameter Tables jump in.

    We’ve seen before how you can create Parameters using the Manage Parameters feature, but what if you want to have your own parameters coming from a Table from any other source?

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    The purpose of having Parameters this way is that it’s dynamic, on every refresh it’ll get the latest values, and it gives another end-user interaction layer, where people can input or change values of parameters completely outside of Power Query / Power BI perhaps on an Excel table, or perhaps on its own storage like a SQL Server database.

    In the end, it’s all about providing the user with the friendliest of experiences based on their specific requirements.

    In this blog post we’ll cover what Parameter Tables are in Power Query / Power BI and the types of Parameter Tables that you can use.

  • Parameters and Functions in Power BI / Power Query–Combine Files Experience

    Combine Files

    I highly recommend that you read the first and second part in this series prior to reading this one, but you can jump right in if you understand the main concepts of parameters, arguments and functions in the M language.

    Understanding the Combine Files Experience: Practical Example

    Consolidation

    The scenario that we’re going to tackle is going to be THE most common way that people use Functions without even knowing what is going on.

    We’ll go over the new Combine Files experience that was introduced in Power BI Desktop at the start of 2017 and how everything changed from there.

  • Parameters and Functions in Power BI / Power Query–Custom Functions

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    Power Query has over 600 native functions and the Power Query team keeps adding more and more.

    I wouldn’t recommend memorizing them, but you do need to understand the concept of parameters and arguments in order to understand what functions are.

    In this blog post I’ll go over what Custom Functions are and how you can create them. Be sure to check out Part 1 of this series before reading this one.

    M Functions

  • Parameters and Functions in Power BI / Power Query – Main Concepts

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    Power Query or the Power BI Get Data Experience uses a functional language called M to perform its Data Preparation or Data Transformation processes.

    You can read this article to get to know more about Power Query and the M language, but in short, Power Query is the interface that assists you, through buttons and dialogs, to create the M code for you.

    Now, where would I see a function, an argument or a parameter in Power Query ?…and what are they? Let’s have a quick example to see them in real life.

  • The most important thing to learn when using Power BI

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    You’ve started OR you’re in the middle of your Power BI journey and you’re confused as to where you should allocate your learning time and efforts

    Should it be DAX? Understanding the visualizations? the M language? Power Query? Power Pivot?

    SOOOO many keywords that appear when doing a simple online search, but WHAT is the core of everything inside of Power BI?

    This article covers my thoughts on where you should primarily focus your efforts when learning Power BI – let’s find out what is the HEART of Power BI.

    After spending more than 6 years using the toolset and going through various iterations and stages of what we now know as Power BI, these are my own thoughts and what I’ve found works best for the people that I’ve trained over the years.

  • Merge Operations in Power BI / Power Query – Part 6: Full Outer Join

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    This is the last post in the series! I highly encourage you to read Part 5 of this series before reading this one, but nevertheless, you can jump right in if you know the basics of Merge / Join Operations inside of Power BI / Power Query.

    We will be using the same sample data that we used in Part 5, but this time we’ll have a completely new goal which is probably one of the most frequent ones that I’ve had when Modelling data for Power BI.

    In this, Part 6, we’ll go over the Full Outer Join from a purely practical standpoint.

  • Merge Operations in Power BI / Power Query – Part 5: Inner Join

    image Similar to the previous posts in this series, I highly encourage you to read the first 4 Parts ( 1 | 2| 3 | 4 ) that I’ve published so far around Merge / Joins inside of Power BI / Power Query.

    So far I’ve covered:

    • Left Outer Join
    • Right Outer Join
    • Left Anti Join
    • Right Anti Join

    In this, Part 5, we’ll go over the Inner Join from a purely practical standpoint.

  • Merge Operations in Power BI / Power Query – Part 4: Right Anti Join

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    Similar to the previous posts in this series, I highly encourage you to read the first 3 Parts ( 1 | 2 | 3 ) that I’ve published so far around Merge / Joins inside of Power BI / Power Query.

    So far I’ve covered:

    • Left Outer Join
    • Right Outer Join
    • Left Anti Join

    In this, Part 4, we’ll go over the Right Anti Join from a purely practical standpoint.

  • Merge Operations in Power BI / Power Query – Part 3: Left Anti Join


    If you haven’t read Part 1 and Part 2 of this series, I highly recommend that you read those prior to this post.

    In those previous posts, we went over the Left Outer Join and Right Outer Joins. At this point we got the basics on how Joins / Merge operations work inside Power Query / Power BI. It’s time to get even more clever with the usage of Merge Operations.

    In this, Part 3, we’ll go over the Left Anti Join from a purely practical standpoint.