Identify and Connect to Data Sources or a Shared Semantic Model (PL-300 Exam Prep)

This post is a part of the PL-300: Microsoft Power BI Data Analyst Exam Prep Hub; and this topic falls under these sections: 
Prepare the data (25–30%) 
    --> Get or connect to data 
        --> Identify and connect to data sources or a shared semantic model

Note that there are 10 practice questions (with answers and explanations) for each section to help you solidify your knowledge of the material. Also, there are 2 practice tests with 60 questions each available on the hub below the exam topics section.

One of the first and most foundational skills tested in the PL-300: Microsoft Power BI Data Analyst exam is the ability to identify, select, and connect to appropriate data sources. This skill lives within the Prepare the data domain and underpins everything that follows—modeling, visualization, and analysis.

A Power BI Data Analyst must understand where data lives, how to connect to it efficiently, and when to reuse existing models instead of building new ones.

Understanding Data Source Types in Power BI

Power BI supports a wide variety of data sources, and the exam expects familiarity with common enterprise and self-service scenarios rather than obscure connectors.

Common Data Source Categories

File-based sources

Excel workbooks
CSV and text files
XML and JSON files
PDF files (structured tables)

Database sources

SQL Server
Azure SQL Database
Azure Synapse Analytics
Oracle
MySQL / PostgreSQL

Cloud and SaaS sources

SharePoint Online lists and files
OneDrive
Dataverse
Azure Blob Storage
Azure Data Lake Storage Gen2

Power Platform and Power BI sources

Power BI datasets (shared semantic models)
Dataflows
Datamarts

Exam tip: You are not expected to memorize every connector—focus on recognizing the correct source for a given scenario.

Choosing the Right Connectivity Mode

When connecting to data, Power BI offers three primary connectivity modes, and the exam frequently tests your understanding of when to use each one.

Import Mode

Data is loaded into the Power BI model
Fast performance
Supports full DAX and modeling capabilities
Requires dataset refreshes

Use when:
Data size is manageable and performance is critical.

DirectQuery Mode

Queries data directly at the source
Minimal data stored in Power BI
Performance depends on the source system
Some modeling and DAX limitations

Use when:
Data is very large or must remain in the source system.

Live Connection

Used with shared semantic models (Power BI datasets) or Analysis Services
No local model created
Modeling is done in the source dataset

Use when:
Connecting to a centrally governed dataset managed by another team.

Connecting to a Shared Semantic Model

A shared semantic model (formerly called a “dataset”) allows analysts to reuse existing data models instead of duplicating logic.

What Is a Shared Semantic Model?

A centrally managed Power BI dataset
Contains curated tables, relationships, measures, and security
Published to the Power BI Service
Designed for reuse across multiple reports

Benefits of Using Shared Semantic Models

Consistent metrics and definitions
Reduced duplication of logic
Centralized governance and security
Faster report development

How to Connect

In Power BI Desktop:

Select Get data
Choose Power BI datasets
Select an existing dataset from the workspace
Create a report using a Live connection

Exam tip:
When connected to a shared semantic model:

You cannot modify relationships
You cannot add calculated tables
You can create report-level measures (thin reports)

Authentication and Access Considerations

The exam also expects awareness of authentication methods, especially in enterprise environments.

Common authentication types include:

Windows authentication
Database authentication
Microsoft Entra ID (Azure AD)
OAuth

Key concept:
Your ability to connect depends on permissions at the source, not just in Power BI.

Identifying the Best Data Source for a Scenario

You may see exam questions that describe a business requirement and ask you to identify the most appropriate data source or connection method.

Example Scenarios

A finance team needs fast, interactive reports → Import mode
A large transactional database updated every minute → DirectQuery
Multiple teams need consistent KPIs → Shared semantic model
Files stored in SharePoint and updated weekly → SharePoint Folder connector

Key Exam Takeaways

For the PL-300 exam, remember the following:

Understand major data source categories
Know Import vs DirectQuery vs Live connection
Recognize when to use shared semantic models
Be aware of limitations when using Live connections
Choose data sources based on performance, governance, and scale

This topic is less about clicking buttons and more about making the right architectural decision—a critical skill for a Power BI Data Analyst.

Power BI Connection Modes – Comparison Table (PL-300 Exam Focus)

Feature / Aspect	Import	DirectQuery	Live Connection
Where data is stored	Loaded into Power BI dataset	Remains in source system	Remains in source dataset or Analysis Services
Performance	Fastest (in-memory)	Depends on source performance	Depends on source dataset
Data refresh required	Yes (scheduled or manual)	No (queries run live)	No (always live)
Data volume support	Limited by dataset size	Very large datasets	Very large datasets
Modeling allowed	Full modeling supported	Limited modeling	No model changes allowed
Create relationships	Yes	Limited	No
Create calculated tables	Yes	Limited	No
Create calculated columns	Yes	Limited	No
Create measures (DAX)	Yes	Yes (with limitations)	Yes (report-level only)
Power Query transformations	Fully supported	Limited (query folding dependent)	Not supported
Row-level security (RLS)	Supported	Supported	Inherited from source
Typical sources	Excel, CSV, SQL, SharePoint	Large SQL, Azure SQL, Synapse	Power BI datasets, Analysis Services
Best use case	High performance, small-to-medium data	Near-real-time or massive data	Reusing governed enterprise models
Exam frequency	Very high	High	Very high

When to Choose Each Mode (Exam Scenarios)

Import Mode

Choose Import when:

Performance is the top priority
Data size is manageable
Full modeling flexibility is needed

📌 Most common and safest answer on the exam unless constraints are stated.

DirectQuery

Choose DirectQuery when:

Data is extremely large
Data must stay at the source
Near real-time reporting is required

📌 Expect questions about performance trade-offs and modeling limitations.

Live Connection

Choose Live Connection when:

Using a shared semantic model
Consistent metrics are required across reports
Centralized governance is in place

📌 Often paired with “thin report” exam scenarios.

High-Value Exam Tips ⭐

If the question mentions enterprise governance or shared datasets → think Live Connection
If it mentions large, frequently changing data → think DirectQuery
If it mentions fast visuals and full modeling → think Import
Live connections do not allow model changes
Import mode requires refresh
DirectQuery relies on query folding

Practice Exam Questions

Go to the Practice Exam Questions for this section.

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Identify and Connect to Data Sources or a Shared Semantic Model (PL-300 Exam Prep)

A Power BI Data Analyst must understand where data lives, how to connect to it efficiently, and when to reuse existing models instead of building new ones.