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All DoD criteria verified: - Rendezvous assignment deterministic (1000 runs test) - Minimal reshuffling on add/remove (≤ 2×1/N bound) - Uniform distribution (64/3/RF1: 15-27 shards/node) - Top-RF placement stable - write_targets returns RG×RF nodes - query_group distributes evenly - covering_set returns one node per shard - merger passes all tests - miroir-core coverage: 91.80% (≥90% required) Test results: 151 passed, 0 failed Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
94 lines
3.7 KiB
Markdown
94 lines
3.7 KiB
Markdown
# Phase 1 — Core Routing: Final Verification
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## Date
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2026-05-09
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## Definition of Done Verification
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### ✅ All Criteria Met
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1. **Rendezvous assignment determinism** ✅
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- `acceptance_determinism_1000_runs`: Verifies identical assignments across 1000 runs
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- `test_rendezvous_determinism`: Basic determinism check
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2. **Minimal reshuffling on node add** ✅
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- `acceptance_reshuffle_bound_on_add`: 64 shards, 3→4 nodes moves ≤ 32 shards (2 × 1/4 × 64)
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- `test_minimal_reshuffling_on_add`: General case verification
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3. **Uniform shard distribution** ✅
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- `acceptance_uniformity_64_shards_3_nodes_rf1`: 64 shards, 3 nodes, RF=1 → each node holds 15–27 shards
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- `test_shard_distribution_64_3_rf1`: Same test with debug output
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4. **Top-RF placement stability** ✅
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- `acceptance_rf2_placement_stability`: RF=2 placement changes minimally on add/remove
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- `test_top_rf_stability`: Top-RF changes verification
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- `acceptance_reshuffle_bound_on_remove`: Remove node behavior
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5. **write_targets returns RG × RF nodes** ✅
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- `test_write_targets_count`: Verifies exact count, uniqueness, and per-group contribution
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6. **query_group distributes evenly** ✅
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- `test_query_group_distribution`: Round-robin distribution verification
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7. **covering_set returns one node per shard** ✅
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- `test_covering_set_one_per_shard`: Exact shard count verification
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- `test_covering_set_replica_rotation`: Intra-group replica rotation
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8. **merger functionality** ✅
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- All merger tests pass: global sort, offset/limit, facet aggregation, field stripping
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- `test_global_sort_by_ranking_score`
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- `test_offset_and_limit_applied_after_merge`
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- `test_facet_counts_summed_across_shards`
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- `test_miroir_shard_always_stripped`
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- `test_ranking_score_stripped_when_not_requested`
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- `test_offset_limit_pagination_reconstruction`
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- `test_stable_serialization_same_input_same_json`
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- And 15+ more merger tests
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9. **miroir-core ≥ 90% line coverage** ✅
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- router.rs: 96.20% line coverage
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- topology.rs: 100.00% line coverage
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- scatter.rs: 100.00% line coverage
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- merger.rs: 94.67% line coverage
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- **Total miroir-core: 91.80% line coverage**
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## Test Results
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- **Total tests**: 151 passed, 0 failed
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- All router tests passing (18+ tests)
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- All topology tests passing (35+ tests)
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- All scatter tests passing (5+ tests)
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- All merger tests passing (20+ tests)
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## Implementation Summary
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### router.rs
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- `score(shard_id, node_id)`: XxHash64 with seed 0 (matches Meilisearch Enterprise)
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- `assign_shard_in_group()`: Deterministic HRW assignment
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- `write_targets()`: Returns RG × RF nodes for writes
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- `query_group()`: Round-robin group selection
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- `covering_set()`: One node per shard with replica rotation
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- `shard_for_key()`: Primary key to shard mapping
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### topology.rs
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- `NodeId`: Unique node identifier
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- `NodeStatus`: 7-state machine with valid transitions
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- `Node`: Health state management, write eligibility
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- `Group`: Replica group with node list
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- `Topology`: Cluster-level groups, nodes, RF, shards
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### scatter.rs
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- `Scatter` trait: Fan-out orchestration (stubbed for Phase 2 wiring)
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- `StubScatter`: Default stub implementation
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- Data structures: `ScatterRequest`, `ScatterResponse`, `NodeResponse`
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### merger.rs
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- `merge()`: Global sort, offset/limit, facet aggregation
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- Field stripping: `_miroir_*` always, `_rankingScore` conditional
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- Binary heap optimization for large fan-out
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- `Merger` trait with `MergerImpl` and `StubMerger`
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## Conclusion
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Phase 1 Core Routing is **complete** and meets all Definition of Done criteria.
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The implementation provides deterministic, coordination-free routing with
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minimal reshuffling on topology changes — the foundation for all subsequent
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phases.
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