Sample project analysis
As per the data refresh questions from the project template (questions 7 and 8), the Power BI dataset only needs to be refreshed daily—there’s not a need for real-time visibility of the data source. From a dataset design perspective, this means that the default import mode is sufficient for this project in terms of latency or data freshness.
The project template from Table 1.2 also advises that an Excel file containing the Annual Sales Plan must be included in addition to the historical sales data in the SQL Server data warehouse. Therefore, unless the Annual Sales Plan data can be migrated to the same SQL Server database containing the Internet Sales and Reseller Sales data, an import mode dataset is the only option.
The data security requirements from the project template can be implemented via simple security roles and therefore do not materially impact the import or DirectQuery decision. DirectQuery datasets can support dynamic or user-based security models as well but, given restrictions on the DAX functions that can be used in security roles for DirectQuery datasets, import mode datasets can more easily support complex security requirements. However, depending on the data source and the security applied to that source relative to the requirements of the project, organizations may leverage existing data source security through a DirectQuery dataset via a single sign-on with Kerberos delegation.
Finally, the BI team must also consider the scale of the dataset relative to size limitations with import mode datasets. As per the project template in Table 1.2 (#6), 3-4 years of sales history needs to be included, and thus the dataset designer needs to determine the size of the Power BI dataset that would store that data. For example, if Power BI Premium capacity is not available, the dataset is limited to a max size of 1 GB. If Power BI Premium capacity is available, large datasets (for example, 10 GB+) potentially containing hundreds of millions of rows can be published to the Power BI service.
The decision for this project is to develop an import mode dataset and to keep the Excel file containing the Annual Sales Plan on a secure network location. The BI team will develop a layer of views to retrieve the required dimension and fact tables from the SQL Server database as well as connectivity to the Excel file. The business is responsible for maintaining the following Annual Sales Plan Excel file in its current schema, including any row updates and the insertion of new rows for future plan years. An excerpt from this file is shown in Figure 1.18:
Figure 1.18: Annual Sales Plan in Excel data table
By using the existing Excel file for the planned sales and margin data rather than integrating this data into the data warehouse, the project is able to start faster and maintain continuity for the business team responsible for this source. Similar to collaboration with all data source owners, the dataset designer could advise the business user or team responsible for the sales plan on the required structure and the rules for maintaining the data source to allow for integration into Power BI.
For example, the name and directory of the file, as well as the column names of the Excel data table, cannot be changed without first communicating these requested revisions. Additionally, the values of the Sales Territory Region, Product Subcategory, and Calendar Yr-Mo columns must remain aligned with those used in the data warehouse to support the required actual versus plan visualizations.
The sales plan includes multiple years and represents a granularity of the month, sales territory region, and product subcategories.
In other words, each row represents a unique combination of values from the Calendar Yr-Mo, Sales Territory Region, and Product Subcategory columns. The Bridge tables section in Chapter 4, Designing Import and DirectQuery Data Models, describes how these three columns are used in integrating the Sales Plan data into the dataset containing Internet Sales and Reseller Sales data.
This completes the sample project analysis and concludes this chapter.
