[Video] Optimizing Parallel Aggregation Using Shared Globals

Hey Community!

We're happy to share a new video from our InterSystems Developers YouTube:

⏯  Optimizing Parallel Aggregation Using Shared Globals @ Ready 2025

https://www.youtube.com/embed/8EWAJ5x5wYo
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This presentation explains an optimization to parallel aggregation in SQL queries using shared globals. Previously, worker processes computed intermediate results separately and sent them to a parent process for serial aggregation, creating delays. The new approach lets all workers write directly and in parallel to a shared global, eliminating the parent bottleneck.

This greatly reduces wait time, especially for queries with many groups. Testing on 20 million rows showed up to a 38% performance improvement, while also simplifying query execution and reducing code complexity.

🗣 Presenter: Elie Eshoa, Systems Developer, InterSystems

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