Question

How do I optimize a Power BI report that takes too long to refresh in Power BI Service?

I need to optimize a Power BI report that takes too long to refresh in Power BI Service, especially when it is connected to large datasets. What are the best practices for improving refresh times, such as using incremental refresh, reducing the complexity of queries, or optimizing data models to enhance performance during the refresh process?

Answer 1

To optimize a Power BI report that takes too long to refresh in Power BI Service, especially with large datasets, follow these best practices:

1. Use Incremental Refresh: Limit data refresh to only new or updated data rather than refreshing the entire dataset. This reduces the volume of data processed and speeds up the refresh time.

2. Simplify Queries: Reduce the complexity of Power Query steps and avoid expensive operations like merging large tables or applying multiple filters. Ensure query folding is enabled to offload processing to the data source.

3. Optimize Data Models: Use star schemas with dimension tables instead of snowflake schemas. Remove unused columns, tables, and relationships to reduce model size. Apply aggregations to summarize data at higher levels and improve refresh performance.

4. Use DirectQuery: For very large datasets, consider using DirectQuery mode, which avoids loading data into Power BI and allows querying the data directly from the source.

5. Monitor and Test: Use Performance Analyzer to identify bottlenecks and optimize refresh queries based on the results.

By applying these techniques, you can significantly reduce the refresh time and improve overall performance.