Fix: Cache upstream dependencies when building the evaluation DAG in scheduler #5569
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Pull Request Overview
This PR adds caching for upstream dependency resolution in the scheduler to optimize performance when handling complex diamond-shaped dependency graphs. The caching prevents redundant traversals of transitive dependencies when multiple paths lead to the same upstream snapshot.
Key Changes
- Modified
_find_upstream_dependenciesto use a cache that memoizes upstream dependencies for each SnapshotId - Changed return types from
List[SchedulingUnit]toSet[SchedulingUnit]to prevent duplicates and maintain uniqueness - Added a new test case covering a complex diamond dependency pattern with multiple convergent paths
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| sqlmesh/core/scheduler.py | Added upstream dependency caching mechanism and changed collection types from lists to sets for deduplication |
| tests/core/test_scheduler.py | Added test case validating correct handling of complex diamond dependency graphs with caching |
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eakmanrq
approved these changes
Oct 30, 2025
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