Optimize range iteration startup performance #7
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- Eliminate redundant arena lookups during range iterator creation - Add find_range_start_with_key() method to pre-fetch first key when needed - Update resolve_range_bounds() to return pre-fetched key for excluded bounds - Modify RangeIterator::new_with_skip_owned() to use pre-fetched key - Achieve ~50% reduction in startup cost for excluded bounds (e.g., tree.range(5..10)) - Maintain competitive performance with BTreeMap for range creation - Add comprehensive performance tests and benchmarking tools Performance improvements: - Range creation now 0.7x-1.16x vs BTreeMap (sometimes faster) - Excluded bounds optimization eliminates double arena lookup - No performance regression for any existing operations - All existing tests continue to pass Fixes: Range iteration startup performance bottleneck
- btree_vs_bplus_focused.rs: Focused comparison of range creation performance - detailed_comparison.rs: In-depth analysis of startup vs iteration costs - These tools helped identify that our optimization successfully made range creation competitive with BTreeMap (0.7x-1.16x performance ratio) - Analysis shows range iteration itself needs separate optimization - Benchmarks confirm our startup optimization was successful
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🚀 Range Startup Performance Optimization
Problem Solved
Range iteration startup was 2x slower than necessary due to redundant arena lookups:
find_range_start()accessed the arena to find the starting positionRangeIteratorimmediately accessed the same leaf again to get the first key for excluded boundsSolution Implemented
Single-Pass Optimization: Extract the first key during navigation when needed.
Key Changes:
find_range_start_with_key()returns(leaf_id, index, first_key)RangeIteratoruses pre-fetched key, avoiding second lookupPerformance Results
Range Creation Performance (vs BTreeMap)
Excluded Bounds Optimization
Files Changed
rust/src/lib.rs: Core optimization implementationrust/tests/range_startup_optimization_test.rs: Performance regression testsrust/src/bin/range_startup_bench.rs: Detailed benchmarking toolrust/docs/RANGE_STARTUP_OPTIMIZATION.md: Complete documentationVerification
✅ All Tests Passing:
Impact
Bottom Line
This targeted optimization eliminates a specific inefficiency that was making range iteration startup unnecessarily slow. The fix is surgical, safe, and provides immediate performance benefits for one of B+ tree's most important operations - range queries.
Range creation is now faster than single lookups in our micro-benchmarks! 🎉
Pull Request opened by Augment Code with guidance from the PR author