PL-300 Hard Questions — 25 Difficult Questions

Question 1

A company has a Power BI dataset that includes a table 'Orders' with columns: OrderID, CustomerID, OrderDate, ShipDate, and Amount. They want to create a measure that calculates the number of orders shipped within 3 days of the order date. Which THREE of the following steps are necessary to create this measure?

Accepted Answer

Use FILTER to filter the Orders table based on the condition.. Option A is correct because FILTER is necessary to iterate over the Orders table and apply a row-by-row condition to identify orders shipped within 3 days. In DAX, FILTER returns a table that can be used as a filter argument inside CALCULATE, enabling context transition and dynamic filtering. Without FILTER, you cannot evaluate the date difference condition for each row individually.

Answer

Use COUNTROWS without any filter.

Answer

Use SUM to add up the Amount column.

Question 2

A Power BI report contains a table visual that displays employee names and their total sales. The data model includes an Employee table with columns: EmployeeID, Name, Department, and HireDate. The Sales table has columns: SaleID, EmployeeID, Amount, and SaleDate. The relationship between Employee and Sales is one-to-many. The user wants to see only employees who have made at least one sale. However, the table shows all employees, including those with no sales (blank Amount). What is the most likely reason?

Accepted Answer

There is no visual-level filter to exclude blank values.. Option D is correct because the table visual is showing all employees due to the absence of a visual-level filter to exclude blank or zero sales amounts. In Power BI, a one-to-many relationship between Employee and Sales means that employees without sales will still appear in the visual unless explicitly filtered out, as the relationship does not automatically suppress rows from the 'one' side when there are no matching rows on the 'many' side.

Answer

The EmployeeID column in the Employee table is hidden.

Answer

The relationship is many-to-one, not one-to-many.

Answer

The relationship direction is set to Single from Employee to Sales.

Question 3

You manage a Power BI deployment that uses deployment pipelines. After promoting content from Development to Test, you notice that the Test workspace dataset uses a different data source than expected. What is the most likely reason?

Accepted Answer

The dataset parameters were not configured in the deployment pipeline rules.. Option C is correct because deployment pipeline rules allow you to configure dataset parameters (such as data source paths) to differ between pipeline stages. If these rules are not set, the dataset retains the data source configuration from the source stage (Development), causing the Test workspace to use an unexpected data source. The pipeline deploys the dataset artifact, but without parameter overrides, the data source connection string remains unchanged.

Answer

The pipeline didn't deploy the dataset because it was already in Test.

Answer

The data source credentials were not applied during deployment.

Answer

The Test workspace has a separate dataset that was manually created.

Question 4

Which THREE steps should you perform to deploy a Power BI solution from development to production using deployment pipelines?

Accepted Answer

Set up deployment pipeline rules to modify parameters (e.g., database name).. Option B is correct because deployment pipeline rules allow you to modify dataset parameters (e.g., database server or database name) when content moves between pipeline stages, ensuring each stage connects to the appropriate data source without manual reconfiguration. This is a core feature of Power BI deployment pipelines to maintain environment-specific settings.

Answer

Create a new workspace manually in production.

Answer

Assign Power BI Pro licenses to all developers.

Question 5

Your Power BI dataset uses DirectQuery to an Azure SQL Database. Users complain that the report is slow. You need to improve query performance without changing the data source. What should you do?

Accepted Answer

Reduce the number of columns and rows retrieved by the report visuals.. Option A is correct because reducing the number of columns and rows retrieved by report visuals directly minimizes the amount of data sent from Azure SQL Database to Power BI via DirectQuery. Since DirectQuery sends native queries to the source for each visual interaction, fewer columns and rows mean smaller, faster queries, which reduces overall latency without altering the underlying data source.

Answer

Add more visuals to the report to distribute the load.

Answer

Switch the dataset to Import mode.

Answer

Increase the scheduled refresh frequency.

Question 6

Which THREE factors should you consider when planning the deployment of Power BI content to a large enterprise with multiple regions?

Accepted Answer

Data residency requirements for each region.. Data residency requirements are critical because Power BI stores data in specific Azure regions. For a multi-region enterprise, you must ensure that data does not leave the required geographic boundary due to compliance or legal mandates. This affects where you provision Power BI tenants, capacity, and data sources.

Answer

The number of visuals per report page.

Answer

The currency format used in reports for each region.

Question 7

You are a Power BI administrator for a large organization. A team has published a shared dataset to a Premium workspace. They use an XMLA endpoint to programmatically refresh the dataset daily. Recently, the refresh started failing with the error: 'The operation was canceled because the session was terminated by a concurrent operation.' The dataset is not partitioned. You need to ensure the refresh completes without errors. What should you do?

Accepted Answer

Enable the 'Refresh conflict detection' setting on the dataset to prevent concurrent operations.. The error 'The operation was canceled because the session was terminated by a concurrent operation' indicates that two refresh operations are conflicting on the same dataset. Enabling 'Refresh conflict detection' on the dataset prevents concurrent refreshes by queuing or blocking overlapping operations, ensuring the XMLA-triggered refresh completes without interruption.

Answer

Remove all scheduled refreshes and rely solely on the XMLA script.

Answer

Change the XMLA script to run less frequently, e.g., once per week.

Answer

Partition the dataset and refresh partitions sequentially.

Question 8

You are reviewing the deployment configuration for a Power BI dataset. The exhibit shows a JSON snippet of the dataset settings. You need to ensure that data is refreshed twice a day at 6:00 AM and 6:00 PM UTC. However, the refresh fails at both scheduled times. What is the most likely cause?

Accepted Answer

The data source uses Integrated Security (SSPI) which is not supported for scheduled refresh.. Option A is correct because scheduled refresh in Power BI requires a gateway to connect to on-premises data sources, and when the data source uses Integrated Security (SSPI), the gateway cannot delegate credentials for scheduled refresh. SSPI relies on the user's interactive Windows authentication context, which is not available during unattended scheduled refresh operations. This causes the refresh to fail at both scheduled times.

Answer

The refresh schedule uses UTC but the data source is in a different time zone.

Answer

The dataset has DirectQuery enabled, which prevents Import mode refresh.

Answer

The gateway ID is incorrect.

Question 9

A Power BI administrator reviews the JSON configuration for a dataset named SalesDataset. The dataset is deployed to a Premium capacity workspace. The data source is an on-premises SQL Server. The administrator notices that the dataset has never refreshed successfully. Based on the exhibit, what is the most likely cause of the refresh failure?

Accepted Answer

The dataset's defaultMode is set to Push, which does not support scheduled refresh. Option C is correct because when a dataset's defaultMode is set to 'Push', it is designed to receive data only via the Push API and does not support scheduled refresh. Since the dataset has never refreshed successfully and the JSON configuration shows defaultMode as Push, the scheduled refresh will always fail regardless of the gateway or data source configuration.

Answer

The refresh schedule specifies a frequency of Weekly, but the time is in UTC and not adjusted for the local time zone

Answer

The dataset uses Integrated Security in the connection string, which is not supported for scheduled refresh

Answer

The dataset is in a Premium capacity workspace, which does not support scheduled refresh for on-premises data sources

Question 10

During data refresh in Power BI, an error occurs: 'The column 'OrderID' of the table 'Orders' contains a duplicate value and this column is part of a primary key.' The table 'Orders' is imported from an Azure SQL database. What is the most likely cause of this error?

Accepted Answer

The source table has duplicate 'OrderID' values.. Option D is correct because the error message explicitly states that the 'OrderID' column contains a duplicate value and is part of a primary key. In Power BI, when importing from a source like Azure SQL Database, the data model enforces uniqueness on primary key columns. If the source table has duplicate 'OrderID' values, the refresh fails because Power BI cannot maintain the required unique constraint.

Answer

The 'Orders' table was reordered in Power Query.

Answer

Data type mismatch between the source and Power BI.

Answer

A calculated column is referencing the 'Orders' table.

Question 11

You have a Power BI dataset that uses DirectQuery to an Azure Synapse Analytics dedicated SQL pool. You need to improve query performance. Which THREE actions should you take?

Accepted Answer

Create indexes on columns used in filters. Creating indexes on columns used in filters is correct because DirectQuery translates Power BI filter operations into SQL queries against the Azure Synapse Analytics dedicated SQL pool. Indexes on those columns accelerate row-level filtering by reducing the number of pages scanned, directly improving query response times.

Answer

Normalize the data warehouse tables

Answer

Switch the dataset to Import mode

Question 12

You are using Power Query to combine data from multiple Excel files in a SharePoint folder. Each file has a sheet named 'Sales'. The columns across files are identical but occasionally a file has extra columns. You need to ensure the combined table contains only the common columns across all files. Which Power Query step should you use?

Accepted Answer

Use Table.ColumnsOfType to filter common columns. Option D is correct because Table.ColumnsOfType allows selecting only columns that appear in all tables. Option A is wrong because Table.Combine appends all columns, creating nulls for missing columns. Option B is wrong because Merge queries are for joining, not combining. Option C is wrong because Remove Other Columns removes columns not selected; you need to identify common ones first.

Answer

Use Table.Combine with the 'Table1' parameter

Answer

Use Remove Other Columns on the first file's columns

Answer

Use Merge Queries as New

Question 13

You are configuring a Power BI dataset with incremental refresh. The above JSON shows part of the M script parameters. The dataset uses a single SQL Server data source. You need to ensure that incremental refresh works correctly. What must you do?

Accepted Answer

Rename the parameter 'StartDate' to 'RangeStart' and add a 'RangeEnd' parameter.. Incremental refresh in Power BI requires two special date/time parameters named 'RangeStart' and 'RangeEnd' (case-sensitive). The JSON snippet shows a parameter named 'StartDate', which is not recognized by the incremental refresh engine. Renaming it to 'RangeStart' and adding a 'RangeEnd' parameter allows Power BI to filter the data source query dynamically during refresh, ensuring only the changed or new rows are loaded.

Answer

Change the connection string to use a SQL account instead of integrated security.

Answer

Enable query folding on the SQL Server source.

Answer

Define the parameters in the Power Query editor instead of the JSON file.

Question 14

You are designing a data model for a retail company. The source system has a Sales table with columns: Date, StoreID, ProductID, SalesAmount. You need to create a date dimension table that includes all dates from the Sales table. Which DAX expression should you use to create the date table?

Accepted Answer

DateTable = CALENDARAUTO(). Option C is correct because `CALENDARAUTO()` automatically generates a contiguous date table spanning all dates present in the model, including those from the Sales table. This function scans all date columns in the model and returns a single column of dates from the earliest to the latest, which is the simplest way to create a date dimension that covers the full range of transaction dates without needing explicit MIN/MAX references.

Answer

DateTable = VALUES(Sales[Date])

Answer

DateTable = CALENDAR(MIN(Sales[Date]), MAX(Sales[Date]))

Answer

DateTable = DISTINCT(Sales[Date])

Question 15

You are designing a data model for a sales analysis report. The source data includes a Sales table with columns: OrderID, CustomerID, ProductID, OrderDate, Quantity, and UnitPrice. You also have a Customers table and a Products table. Which approach best optimizes query performance and storage?

Accepted Answer

Create a star schema with Sales as a fact table and Customers and Products as dimension tables.. Option A is correct because a star schema optimizes query performance and storage in Power BI by separating transactional data (Sales fact table) from descriptive attributes (Customers and Products dimension tables). This reduces data duplication, improves compression, and enables efficient aggregations and filter propagation via one-to-many relationships, which is the recommended modeling approach for analytical workloads.

Answer

Create separate fact tables for each dimension.

Answer

Create a single flat table by joining all columns from Sales, Customers, and Products into one table.

Answer

Create a snowflake schema by normalizing Customers into multiple related tables.

Question 16

Refer to the exhibit. The Power Query M code imports a CSV file. The import succeeds, but the 'OrderDate' column shows some dates as null even though they appear valid in the CSV. What is the most likely cause?

Accepted Answer

The date format in the CSV is not recognized by the locale used in the transformation.. Option A is correct because the '#Changed Type' step converts the column to type date, which will fail for any value that is not a valid date, resulting in null. If the CSV contains dates in a non-standard format (e.g., 'MM/dd/yyyy' vs 'dd/MM/yyyy'), the conversion may produce null. Option B is wrong because promoted headers only affect the first row. Option C is wrong because replacing 'null' with null would not affect dates. Option D is wrong because filtering rows does not affect data types.

Answer

The 'Filtered Rows' step removes rows where Amount > 0, which may include valid dates.

Answer

The 'Promoted Headers' step incorrectly changes the data type of the OrderDate column.

Answer

The 'Replaced Value' step replaces 'null' with null, causing the date to become null.

Question 17

You are reviewing a Power BI data source configuration in the data source settings. The exhibit shows the JSON representation of a data source. Which issue might arise from this configuration?

Accepted Answer

The authentication kind 'Key' is not supported for Azure SQL Database, causing connection failure.. Option D is correct because Azure SQL Database does not support the 'Key' authentication kind in Power BI data source settings. Azure SQL Database requires either Windows authentication, database credentials (Username/Password), or Azure AD-based authentication (such as OAuth2 or Service Principal). The 'Key' authentication kind is typically used for Azure Storage or Cosmos DB, not for Azure SQL Database, so this configuration will cause a connection failure.

Answer

The server name contains a hyphen, which is invalid in SQL Server connection strings.

Answer

The CommandTimeout value is too low and may cause queries to time out.

Answer

The option 'CreateNavigationProperties' is set to false, which may prevent relationships from being created.

Question 18

You are reviewing a Power Query M expression that transforms column types. The 'SalesAmount' column contains values like '1,234.56' (with a comma as thousands separator). After applying this transformation, what is the likely result?

Accepted Answer

The transformation will result in errors for rows containing commas.. Option A is correct because Power Query's default type conversion for numeric columns expects a period as the decimal separator and no thousands separator. When the 'SalesAmount' column contains values like '1,234.56' with a comma as a thousands separator, attempting to convert the column directly to a number type (e.g., using 'Change Type' or 'Table.TransformColumnTypes') will cause errors for rows containing commas, as Power Query cannot parse the comma as part of a valid number. The comma is not a recognized numeric character in the default locale, so the conversion fails.

Answer

The column will be converted to text automatically.

Answer

The column will be successfully converted to numbers.

Answer

The transformation will ignore the comma and convert the number correctly.

Question 19

Which THREE actions in Power Query Editor can improve the performance of data refresh? (Select three.)

Accepted Answer

Remove columns that are not used in the report.. Option C is correct because removing unused columns reduces the amount of data loaded into the Power Query engine and the data model, directly decreasing memory usage and refresh time. Power Query processes all columns in a query step, so eliminating unnecessary columns early minimizes the data footprint for subsequent transformations and the final load.

Answer

Sort data in ascending order to improve compression.

Answer

Merge queries before filtering.

Question 20

You are debugging a Power Query that imports a CSV file. The exhibit shows the M code. The CSV file contains a header row and data. Some rows have a comma inside a quoted field (e.g., "Smith, John"). What issue will arise from this code?

Accepted Answer

The QuoteStyle.None option will cause commas inside quotes to be treated as delimiters.. Option B is correct because the M code uses `QuoteStyle.None`, which tells Power Query to treat commas inside quoted fields as column delimiters rather than as part of the field value. This causes rows with values like "Smith, John" to be split incorrectly, resulting in extra columns and misaligned data. The correct option for CSV files with quoted fields is `QuoteStyle.Csv`, which respects the standard CSV quoting rules.

Answer

The encoding 1252 is incorrect for the file.

Answer

The number of columns specified (5) is too many.

Answer

The Promoted Headers step will fail because the first row contains quotes.