Power BI - Questions & Answers | Business Analytics & Intelligence | Processes & Tools | Part 7

Question: What techniques can be used to reduce the file size of a Power BI report?

Suggested Answer:

Reducing the file size of a Power BI report (.pbix) improves performance, reduces load times, and makes sharing easier. 

Key techniques to reduce file size

1. Optimize Data Sources

Import Mode vs. DirectQuery/Dual Mode:

• Use DirectQuery or Live Connection for large datasets instead of importing.
• If importing, filter unnecessary data at the source.

Use Query Folding: Ensure Power Query transformations are pushed to the source (SQL, etc.).

Limit Rows: Load only necessary historical data (e.g., last 3 years instead of 10).

2. Clean & Transform Data Efficiently

Remove Unused Columns: Delete unnecessary columns in Power Query.

Use Appropriate Data Types: Smaller types (e.g., integer instead of text for IDs) reduce size.

Replace High-Cardinality Text with IDs: Use numeric keys instead of long text labels.

Avoid Complex Columns: JSON/XML columns bloat size—parse them in Power Query.

3. Optimize Data Model

Star Schema Design: Use fact/dimension tables to avoid redundancy.

Disable Auto Date/Time: Turn off "Auto Date/Time" in Options > Data Load to avoid hidden tables.

Reduce Calculated Columns: Prefer measures (calculated at runtime) over columns.

Limit Relationships: Remove unused relationships.

4. Manage DAX & Measures

Avoid Bloated DAX: Complex CALCULATE/ITERATE operations increase size.

Use Variables (VAR): Improves efficiency and reduces redundancy.

5. Optimize Visuals & Report Design

Remove Unused Visuals: Delete hidden or redundant visuals.

Limit Slicers/Filters: Too many slicers increase file size.

Use Static Images: Avoid high-resolution logos (compress them first).

6. Compress Images & Media

Compress Images: Use tools like TinyPNG before importing.

Avoid Embedded Videos: Link externally instead.

7. Use Aggregations

Implement Aggregation Tables: Summarize large datasets for faster performance.

8. Split Large Reports

Break into Multiple .pbix Files: Separate dashboards logically.

Use Power BI Paginated Reports for detailed data.

9. Clear Cache & Temp Files

Purge Unused Data: Use File > Options > Data > Clear Cache.

Compact File: After deletions, save a fresh copy (Power BI may not shrink automatically).

10. Use Power BI Premium/Dedicated Capacity

Leverage Premium Features: Large models perform better in Premium/PPU workspaces.

Bonus: Post-Save Optimization

Zip & Re-save: Sometimes, re-saving after deletions reduces size further.

By applying these techniques, we can significantly reduce .pbix file size while maintaining performance. Test changes incrementally to ensure accuracy.