Query Performance Tuning In Power BI(Part-1)

DataSculptsInsights
Microsoft Power BI
Published in
3 min readFeb 26, 2024

Reducing the Data Size

Introduction

Optimizing query performance in Power BI often begins by managing the data size. A streamlined dataset can greatly enhance data refresh times and improve report responsiveness. In this article, we’ll discuss practical strategies for reducing data size, using real-world data analytics scenarios as examples.

Data Modeling Best Practices

Choosing the Right Granularity

Selecting the appropriate level of detail for your data is crucial. For instance, if your reports focus on monthly sales trends, you might not need daily transaction-level details.

Real-Life Example: A data analyst at DataSculptsInsights reduced the dataset size by aggregating daily sales data into monthly summaries, keeping the necessary granularity for trend analysis without the excess detail of daily transactions.

Removing Unnecessary Columns and Tables

Evaluate your data model and remove any columns or tables that aren’t needed for your analysis. This reduces the size and simplifies your model, making it easier to maintain.

Real-Life Example: At DataSculptInsights, a data analyst is engaged in crafting a salary report for a corporate client. The primary source for this report is the ‘Employee’ table, which, although rich in information, contains several columns that are not pertinent to the report’s objectives. To streamline the report and enhance its efficiency, the analyst strategically eliminates these superfluous columns, thereby refining the data model to focus solely on the necessary elements for the salary analysis. This step not only simplifies the report but also makes it more concise and relevant to the task at hand.

Data Compression Techniques

Using Efficient Data Types

Opt for data types that use less space. For example, use integers instead of strings for identifiers.

Real-Life Example: Switching a customer ID field from a string to an integer significantly reduced the dataset size, as integers take up less space than strings.

Column Encoding Methods

Power BI automatically compresses data, but understanding how it works can help you model data more efficiently. For instance, columns with fewer unique values compress better.

Real-Life Example: A sales dataset was restructured so that a column with hundreds of unique text values was replaced with a numerical category ID, improving compression.

Incremental Data Loading

Incremental loading fetches only the data that has changed or been added since the last refresh, rather than the entire dataset.

Real-Life Example: A data analyst at DataSculptsInsights devised a more efficient approach for managing a sizable sales dataset. By adopting an incremental load strategy, they focused on updating only the data for the current year on a daily basis. This targeted refresh method led to a significant reduction in the overall refresh time.

Conclusion

By implementing these strategies, you can significantly reduce your data size in Power BI, leading to faster refresh times and more responsive reports. In the next part of this series, we’ll dive into optimizing Direct Query for even better performance.

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