Getting data into Power BI is the first step to creating a report or dashboard in this visualization tool powered by Microsoft. Power BI offers two main methods for connecting to data sources: Import and Direct Query. While both approaches have their strengths, they are designed to serve different use cases depending on your reporting needs, the size of the dataset, and performance requirements. 

In this blog, we’ll explore the key differences between Import and Direct Query, their pros and cons, and when to use each in Power BI.

What is Import Mode?

Import mode in Power BI is the most common type of data connection type that most people use in their reports. Import Mode means you basically bring in a copy of the data into the Power BI data model and store the data. There is no live connection with your data source. We can use this to import the data from an Excel or CSV file and create a report based on that imported data. However, this means that data is not refreshed in real-time and will have to be either updated manually or programmed using scheduled refresh in Power BI Service.

What Is Direct Query?

Direct Query, on the other hand, means you are directly querying the data from the data source with a live connection to it. There is no data stored within Power BI, instead, every time there is any interaction with the filters or charts, Power BI will run the query again in run time to fetch data from the data source. 

This means data is always up to date and there is no lag in data update which makes it great for real-time dashboards and reports. You are always querying the data that is present in the data source itself. However, this may impact the speed and performance of your report given the load it takes to refresh the report on every hit. 

Pros and Cons

I am sure you are wondering how this affects your decision-making when creating your next report in Power BI. 

Let’s understand the advantages and drawbacks of these two types of data connection in Power BI to understand how to make use of these different modes in your reporting. 

Why You Should Use Import Mode

Import mode has several advantages why people may prefer it over Direct Query:

• Fast Performance: Since the data is stored in Power BI’s memory, reports and visualizations load quickly, providing a smooth user experience.

• Advanced Features: Import mode supports the full range of Power BI features, including calculated columns, DAX functions, complex transformations, and aggregations.

However, Import mode might not be the best choice when you work with real-time data or large datasets which Power BI may struggle to keep in memory.

Why You Should Use Direct Query Mode

Besides the obvious benefit of using Direct Query, which is real-time update data, there are other benefits to using this type of connection in Power BI:

• No Memory Constraints: Since data isn’t stored in Power BI’s memory, you can work with very large datasets without worrying about memory limits.

• Seamless Data Management: Direct Query allows data to be updated in Power BI as soon as data is updated in the source. This means that any updates made in the source system are immediately reflected in Power BI reports.

Direct Query does come with the added load time in terms of the performance of your reports. Use Direct Query with caution and only when it's necessary to your report to ensure your reports don’t become laggy and slow to load. 

When To Use Import vs Direct Query Modes In Power BI

Typically, it is advised to use Import mode when you want your report to be fast, reliable, and real-time data is not of high priority. Also, it is best when the report might involve heavy transformation and complex DAX functions and measures. 

On the other hand, use Direct Query when your report works with real-time data. Let's say you are working on a Sales dashboard where the data warehouse generates large volumes of data and you want to see the live order numbers of your business which is updated every minute. However, do remember to use this only when required for your specific requirement - otherwise, the overall performance of your report will be slower than optimum. 

Direct Query is also useful when working with large datasets as Power BI may not be able to store such large datasets in its memory.

Composite Models 

Now you can also use composite models in Power BI which allows you to combine Import mode and Direct Query mode in your reports. This means you can essentially store your dimension tables in Import mode and fact tables in direct query mode allowing for real-time data updates. 

The composite model provides flexibility, enabling you to balance performance with data freshness, depending on the specific needs of different datasets.

Conclusion

Choosing between Import and Direct Query in Power BI depends largely on your data size, performance needs, and the importance of real-time access. For fast, feature-rich analysis, Import mode is often the best choice. However, if your business needs to rely on real-time data or you’re dealing with massive datasets, Direct Query may be more suitable.

I hope this gives you a good understanding between Import Mode and Direct Query Mode in Power BI. You are now in a good position to work with complex datasets and to create reports based on those datasets. Remember, to use this knowledge to your advantage in your next report to fully utilize the ‘power’ of Power BI! 

FAQs

Which is faster: Import or Direct Query?

Import connection type typically tends to be faster than Direct Query in terms of data load time. There are several other factors that can impact your report performance however Import tends to be faster in most cases. 

Can you use DAX in a direct query?

Yes, you can use DAX in Direct Query, although some of the functions you can use are restricted. Using Import mode ensures that you are able to use all DAX functions.