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GraphQLConf 2026 has ended
May 19 - 20 | In-Person Only
GraphQLConf 2026 website

The Sched app allows you to build your schedule but you must also be registered for GraphQLConf 2026 to participate in the sessions.

Please note: This schedule is automatically displayed in Pacific Daylight Time (UTC-7). To see the schedule in your preferred timezone, please select from the drop-down located at the bottom of the menu to the right.

IMPORTANT NOTE: Timing of sessions and room locations are subject to change.
Tuesday May 19, 2026 11:40am - 12:05pm PDT
Pretty much every major GraphQL execution implementation follows the same pattern: depth-first traversal. But the spec doesn’t require this. At Shopify, we challenged that status quo and rewrote GraphQL execution to run breadth-first.

Here’s how it works: instead of running a field resolver repeatedly across each object in a list during its depth pass, we execute each field resolver only once per selection with a complete breadth of objects spanning the response. The napkin math is compelling—5 fields resolved across a list of 100 objects running depth-first will produce 500 resolver calls + lazy promises, while running breadth-first will only produce 5. We’ve seen dramatic results with some large list queries shaving many seconds off their end-to-end response times.

This talk will cover:

* Why depth-first has hidden costs that scale linearly.
* How breadth-first inverts the cost model.
* Why dataloaders are a hack.
* The trade-offs we accepted.
* How we're incrementally migrating to breadth execution.

If you've ever been concerned that CPU-bound GraphQL performance doesn't scale well, this talk offers a new perspective—and proof that challenging conventions can pay off.
Speakers
avatar for Greg MacWilliam

Greg MacWilliam

Staff Software Engineer, Shopify
Greg is an API Foundations engineer at Shopify focused on GraphQL scalability and performance. He’s an open-source contributor on several GraphQL projects, and author of The Schema Stitching Handbook. Coder. Dad. Likes dogs, juggles fire.
Tuesday May 19, 2026 11:40am - 12:05pm PDT
Boardroom
  Performance

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