refactor(metrics): optimize addDimensions method to avoid O(n²) complexity
#4156
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dreamorosi
changed the title
addDimensions method to avoid O(n²) complexity
svozza
approved these changes
Jul 9, 2025
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@aws-powertools/lambda-typescript No related issues found. Please ensure 'pending-release' label is applied before releasing. |
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Summary
Changes
Replace
Object.assignusage indimensionSetsreducer with direct property assignment to improve time complexity from O(n²) to O(n). The previous implementation copied all accumulator properties on each iteration, while the new approach mutates the accumulator directly using afor...ofloop.This change maintains identical behavior while significantly improving performance for metrics with multiple dimension sets, especially in high-throughput Lambda functions.
This PR addresses a performance bottleneck in the Metrics utility where
Object.assignwas used in a reducer pattern, causing O(n²) time complexity. The fix follows the established coding guidelines that recommend avoidingObject.assignin accumulators and usingfor...ofloops instead.Issue number: Fixes #4155
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