What is the difference between Direct Query and SQL Server import in ? Power BI interview questions and answers 075

What is the difference between Direct Query and SQL Server import in ? 

Here's a detailed explanation of the differences between DirectQuery and SQL Server import in Power BI:

Data Storage and Handling:

• Import:

• Copies data from the SQL Server database into the Power BI file.

• Stores data locally within the file, creating a compressed dataset.

• Uses local processing for visualizations and calculations.

• DirectQuery:

• Keeps data in the SQL Server database.

• Queries data directly from the source on-demand when interacting with visualizations.

• Relies on the source database for processing queries.

Performance:

• Import:

• Often faster for interactive visualizations and calculations due to local data storage and processing.

• Initial import can take time for large datasets.

• DirectQuery:

• Performance depends on the underlying database performance and network connectivity.

• Can be slower for complex visualizations or large datasets, as queries are sent to the database each time.

Data Refresh:

• Import:

• Requires manual or scheduled refreshes to update the dataset with new data from the source.

• DirectQuery:

• Displays the most up-to-date data without manual refreshes, as it queries the source directly.

Data Transformations:

• Import:

• Allows extensive data transformations and shaping using Power Query before importing.

• DirectQuery:

• Limited to transformations supported by the SQL Server database and its query language.

• Complex transformations might need to be performed in the database itself.

Data Modeling:

• Import:

• More flexibility in creating complex data models with multiple relationships and measures.

• DirectQuery:

• Certain modeling features might be restricted or unavailable due to reliance on the source database's capabilities.

Use Cases:

• Import:

• Ideal for smaller to medium-sized datasets with frequent interactivity and analysis.

• Suitable when extensive data transformations or complex modeling are required.

• DirectQuery:

• Better for very large datasets or near-real-time data visualization.

• Preferred when showcasing the latest data from a frequently changing source.

• Useful when direct database access is necessary for security or compliance reasons.

Choosing the Right Method:

The best choice depends on your specific needs, considering factors like:

• Dataset size

• Data refresh frequency

• Performance requirements

• Data transformation needs

• Data modeling complexity

• Security and compliance considerations