My team is using Tableau with Databricks on Delta Lake. We're seeing a bunch of slow queries (around 20%) that for some reason involve massive scans - 5x to 30x more - compared to the median queries.

Summary

A recent issue with slow queries in Tableau using Databricks on Delta Lake raises concerns about query optimization and performance.

Investigation of Slow Queries

Tableau users reported that approximately 20% of their queries experience significant delays, with scans being 5 to 30 times higher than median values. This appears to be linked to how Tableau constructs queries, particularly when "Show Missing Values" is enabled for continuous dates, leading to suboptimal performance in the Databricks environment.

Importance for BI Professionals

This issue touches on broader themes in business intelligence, such as the need for effective query optimization and the importance of tool collaboration. Competitors of Tableau, like Power BI, may join this conversation as companies seek to maximize the efficiency of their BI practices. The trend towards cloud-based solutions and advanced data analytics tools underscores the significance for BI professionals to understand how to best utilize their platforms.

Concrete Takeaway

BI professionals should be vigilant about the performance of their queries and methods to optimize them. It is advisable to explore best practices regarding query construction and configurations in Tableau, as well as review settings in Databricks to minimize delays.