Incremental Refresh in Power BI, Part 1: Implementation in Power BI Desktop

Incremental-Refresh-in-Power-BI-Part-1-Implementation-in-Power-BI-Desktop

Incremental refresh, or in short, IR, refers to loading the data incrementally, which has been around in the world of ETL for data warehousing for a long time. Let us discuss incremental refresh (or incremental data loading) in a simple language to better understand how it works.

From a data movement standpoint, there are always two options when we transfer data from location A to location B:

  1. Truncation and load: We transfer the data as a whole from location A to location B. If location B has some data already, we entirely truncate the location B and reload the whole data from the location A to B
  2. Incremental load: We transfer the data as a whole from location A to location B just once for the first time. The next time, we only load the data changes from A to B. In this approach, we never truncate B. Instead, we only transfer the data that exists in A but not in B

When we refresh the data in Power BI, if we have not configured an incremental refresh, we use the first approach, which is truncation and load. Needless to say that in Power BI, the first approach only applies to tables with Import or Dual storage modes. Previously, the Incremental load was available only in the tables with either Import or Dual storage modes. But the new announcement from Microsoft about Hybrid Tables makes a big difference in how Incremental load works. With the Hybrid Tables, the Incremental load is available on a portion of the table when a specific partition is in Direct Query mode, while the rest of the partitions are in Import storage mode.

Incremental refresh used to be available only on Premium capacities, but from Feb 2020 onwards, it is also available in Power BI Pro with some limitations. However, the Hybrid Tables are currently available on Power BI Premium Capacity and Premium Per User (PPU) and not Pro. Let’s hope that Microsft will change its licensing plan for the Hybrid Tables in the future and make it available in Pro.

I will write about Hybrid Tables in a future blog post.

When we successfully configure the incremental refresh policies in Power BI, we always have two ranges of data; the historical range and the incremental range. The historical range includes all data processed in the past, and the incremental range is the current range of data to process. Incremental refresh in Power BI always looks for data changes in the incremental range, not the historical range. Therefore, the incremental refresh will not notice any changes in the historical data. When we talk about the data changes, we are referring to new rows inserted, updated or deleted, however, the incremental refresh detects updated rows as deleting the rows and inserting new rows of data.

Benefits of Incremental Refresh

Configuring incremental refresh is beneficial for large tables with hundreds of millions of rows. The following are some benefits of configuring incremental refresh in Power BI:

  • The data refreshes much faster than when we truncate and load the data as the incremental refresh only refreshes the incremental range
  • The data refresh process is less resource-intensive than refreshing the entire data all the time
  • The data refresh is less expensive and more maintainable than the non-incremental refreshes over large tables
  • The incremental refresh is inevitable when dealing with massive datasets with billions of rows that do not fit into our data model in Power BI Desktop. Remember, Power BI uses in-memory data processing engine; therefore, it is improbable that our local machine can handle importing billions of rows of data into the memory

Now that we understand what incremental refresh is, let us see how it works in Power BI.

Implementing Incremental Refresh Policies with Power BI Desktop

We currently can configure incremental refresh in the Power BI Desktop and in Dataflows contained in a Premium Workspace. In this blog post, we look at the incremental refresh implementation within the Power BI Desktop.

After we successfully implement the incremental refresh policies with the desktop, we publish the model to Power BI Service. The first data refresh takes longer as we transfer all data from the data source(s) to Power BI Service for the first time. After the first load, all future data refreshes will be incremental.

How to Implement Incremental Refresh

Implementing incremental refresh in Power BI is simple. There are two generic parts of the implementation:

  1. Preparing some prerequisites in Power Query and defining incremental policies in the data model
  2. Publishing the model to Power BI Service and refreshing the dataset

Let’s briefly get to some more details to quickly understand how the implementation works.

  • Preparing Prerequisites in Power Query
    • We require to define two parameters with DateTime data type in Power Query Editor. The names for the two parameters are RangeStart and RangeEnd, which are reserved for defining incremental refresh policies. As you know, Power Query is case sensitive, so the names of the parameters must be RangeStart and RangeEnd.
    • The next step is to filter the table by a DateTime column using the RangeStart and RangeEnd parameters when the value of the DateTime column is between RangeStart and RangeEnd.

Notes

  • The data type of the parameters must be DateTime
  • The datat tpe of the column we use for incremental refresh must be Int64 (integer) Date or DateTime.Therefore, for scenarios that our table has a smart date key instead of Date or DateTime, we have to convert the RangeStart and RangeEnd parameters to Int64
  • When we filter a table using the RangeStart and RangeEnd parameters, Power BI uses the filter on the DateTime column for creating partitions on the table. So it is important to pay attention to the DateTime ranges when filtering the values so that only one filter condition must have an “equal to” on RangeStart or RangeEnd, not both
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Power BI 101, What Should I Learn?

This is the second part of my new series of Power BI posts named Power BI 101. In the previous post, I briefly discussed what Power BI is. In this post, I look into one of the most confusing parts for those who want to start learning Power BI. Many people jump straight online and look for Power BI training courses which there are plenty out there. But which one is the right training course for you? Let’s find out.

What do you want to gain from learning Power BI?

Regardless of attending paid training courses or being a self-learner, the above question is one of the most important questions you might ask yourself before going to the next steps. The answer to this question dictates the sort of training you must look for. Your answer to the preceding question can be one or none of the following:

  • I am a graduate/student looking at the job market
  • I am a business analyst and I want to know how Power BI can help you with my daily job
  • I am a database developer and I want to learn more about business intelligence and data and analytics space
  • I am a non-Microsoft Business Intelligence developer and I want to start learning more about Microsoft offerings
  • I am a system admin and I have to manage our Power BI tenant
  • I am a data scientist and I want to know how I can use Power BI
  • I am just ciourious to see what Power BI can do for me

As mentioned, your answer might not be any of the above, but, thinking about your reason(s) for learning Power BI can help you to find the best way to learn and use Power BI more efficiently. You can spend time and money taking some online courses and get even more confused. You don’t want that do you?

So, whatever reason(s) you have in mind to learn Power BI, most probably you fall into one of the following user categories:

Think about your goal(s) and what you want to achieve by learning Power BI then try to identify your user category. For instance, if you are a student thinking of joining an IT company as a data and analytics developer, then your user category is most probably a Power BI Developer or a Contributor.

To help you find out your user category let’s see what the above user categories mean.

Power BI Developers

The Power BI Developers are the beating hearts of any Power BI development project. Regardless of the project you will be involved with, you definitely require to have a certain level of knowledge of the following:

  • Data preparation/ETL processes
  • Data warehousing
  • Data modelling/Star schema
  • Data visualisation

To be a successful Power BI developer you must learn the following languages in Power BI:

  • Power Query
  • DAX

Depending on the types of projects you will be involved in, you may require to learn the following languages as well:

  • Microsoft Visual Basic (for Paginated Reports)
  • Python
  • R
  • T-SQL
  • PL/SQL

As a Power BI developer, you will write a lot of Power Query and DAX expressions. Most probably you require to learn T-SQL as well. The following resources can be pretty helpful:

Continue reading “Power BI 101, What Should I Learn?”

Power BI 101, What is Power BI

Many people talk about Power BI, its benefits and common challenges, and many more want to learn Power BI, which is excellent indeed. But there are many misconceptions and misunderstandings amongst the people who think they know Power BI. In my opinion, it is a significant risk in using tools without knowing them, and using the technology is no different. The situation is even worse when people who must know the technology well don’t know it, but they think they do. These people are potential risks to the businesses that want to adopt Power BI as their primary analytical solution across the organisation. As a part of my day-to-day job, I communicate with many people interacting with Power BI. Amongst many knowledgeable users are some of those who confuse things pretty frequently, which indicates a lack of understanding of the basic concepts.
So I decided to write a series of Power BI 101 to explain the basics of the technology that we all love in simple language. Regardless of your usage of Power BI, I endeavour to help you know what to expect from Power BI. This is the first part of this series.

What is Power BI?

I do not frequently get the “What is Power BI” question from my customers, my website’s comments, or my students within the training courses. It is indeed a question that I often ask people. I usually ask the question to indicate people’s level of understanding on different occasions, such as when a friend wants to know more about Power BI, or in a job interview from a candidate who applied for a Power BI related role, or my students attending a training course. Depending on the context that I ask the question, the responses are often pretty different.

It is the general rule of thumb to know what a “thing” is before using it. The “What is X?” (and X is the name of a “thing”) is a broad question, so the answer is also broad. Therefore we usually need more digging to get a better understanding of the “thing”. 

In our case, the “thing” is Power BI, so the question is “What is Power BI?”. And the answer is:

“Power BI is the Business Analytics platform part of a larger SaaS platform called Power Platform offering from Microsoft.”

Now, let’s dig a bit more with two more questions:

  • What is a Data Platform?
  • What is Saas?

Let’s quickly answer those questions.

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Power BI Ecosystem Report Authoring Tools Demystified

Power BI Reporting Tools Confusion

There are a lot of discussions these days around Power BI tools to create reports and for sure many of you may have already downloaded and worked with some of them if not all of them. You may already think that some of the tools’ names are confusingly similar. I recently had an interesting conversation with a fellow who has a lot of SSRS report writing background. I was talking about Paginated reports and said, I downloaded the latest version of Power BI Report Builder… that he immediately said, wait for a second…

  • John: Power BI Report Builder? Oh I see, that’s the one that you can create paginated reports with then you can deploy those reports into an SSRS instance.
  • me: NOPE! That’s not the case I’m afraid.
  • John: Oh I know, I meant Power BI Report Server, you can deploy the reports to an instance of Power BI Report Server. I knew it!
  • me: NO! That’s not what I’m talking about…
  • John: What the…?

I bet some of you had a similar conversation with a friend or a customer. OK, in this post I explain a little bit about report authoring tools available to you and your organisation to get the most out of your Power BI ecosystem.

Here is a list of all reporting tools currently available to you:

  • Power BI Service: It is a SaaS (Software as a Service) offering from Microsoft in the cloud. The users in an organisation, based on their access rights, may be able to create and publish data, reports, dashboards in Power BI Service. The users can also schedule data refreshes on the published data as well as securely sharing and distributing the contents. While creating or editing reports is possible in Power BI Service, it is strongly recommended to avoid this method for several reasons. The most obvious one is that the changes you make in a report may be soon get overwritten by someone else that republishes the same report from Power BI Desktop. Check this blog post from SQLChick to see why you should avoid creating or editing reports directly from Power BI Service. The reports are downloadable in PBIX format. Use Power BI Service here.
  • Power BI Desktop: It is a desktop report authoring tool that can be used to connect to, or loading data from, varies types of data sources, preparing, transforming and cleansing that data and at last visualising the data. Power BI Desktop is the predominant report authoring tool with a lot more functionalities and flexibility than Power BI Service. For instance, setting up Role Level Security (RLS) is NOT available in Power BI Service. The format of the report file is PBIX. Download Power BI Desktop from here.
  • Power BI Report Builder (Paginated): Paginated reports aka “pixel perfect reports”, as the name resembles, are formatted in a way to fit perfectly on a page. That report page might later be printed. You have exact control over the page formatting to display your data in tables or charts. The reports are not as interactive as Power BI Desktop reports are. Paginated reports are based on RDL technology which is standard report format in SQL Server Reporting Services. The tool for developing paginated report in Power BI ecosystem is Power BI Report Builder. The reports file type is RDL. You can currently publish Paginated reports only to a Workspace that is backed with a premium capacity. Download Power BI Report Builder from here.
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