6d91e81b6e
Implemented POST /indexes/{uid}/search with:
- Group selection: query_seq % RG (plan §2)
- Intra-group covering set (plan §4 covering_set)
- Fan-out to covering set with showRankingScore: true
- Each node returns offset + limit results (coordinator pagination)
- Merge with RRF or Score-based strategy (P1.4)
- Unavailable shard policies: partial, error, fallback
- X-Miroir-Degraded header with shard IDs
All 10 acceptance tests pass:
- Unique-keyword deduplication
- Facet count aggregation
- Paging consistency
- Node failure handling with RF=2
- Group fallback on full group failure
- Degraded header with shard IDs
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
93 lines
3.5 KiB
Markdown
93 lines
3.5 KiB
Markdown
# P2.3 Search Read Path Implementation Summary
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## Overview
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The search read path with scatter-gather + merge + group selection is fully implemented and tested.
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## Implementation Components
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### 1. Group Selection (`query_group`)
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- **Location**: `crates/miroir-core/src/router.rs:98-103`
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- **Logic**: `query_seq % RG` (round-robin through replica groups)
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- **Status**: ✅ Implemented
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### 2. Intra-group Covering Set (`covering_set`)
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- **Location**: `crates/miroir-core/src/router.rs:105-116`
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- **Logic**: Uses rendezvous hash to select RF replicas per shard
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- **Rotation**: Rotates through replicas using `query_seq`
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- **Status**: ✅ Implemented
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### 3. Scatter Planning (`plan_search_scatter`)
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- **Location**: `crates/miroir-core/src/scatter.rs:387-431`
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- **Logic**: Builds `ScatterPlan` mapping shards to nodes
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- **Features**:
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- Supports replica_selector for adaptive selection
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- Version floor filtering (plan §13.5)
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- Session pinning support (plan §13.6)
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- **Status**: ✅ Implemented
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### 4. Execute Scatter (`execute_scatter`)
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- **Location**: `crates/miroir-core/src/scatter.rs:598-742`
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- **Logic**: Fans out search requests to all nodes in covering set
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- **Features**:
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- Parallel requests with `join_all`
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- Unavailable shard policies: Partial, Error, Fallback
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- Group fallback on failure (plan §2)
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- **Status**: ✅ Implemented
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### 5. Request Transformation (`SearchRequest::to_node_body`)
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- **Location**: `crates/miroir-core/src/scatter.rs:341-376`
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- **Logic**: Injects `showRankingScore: true` unconditionally
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- **Pagination**: Sets `limit = offset + limit`, `offset = 0`
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- **Status**: ✅ Implemented
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### 6. Merge (`scatter_gather_search`, `merge`)
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- **Location**: `crates/miroir-core/src/scatter.rs:745-785`, `crates/miroir-core/src/merger.rs`
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- **Strategies**:
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- RRF (Reciprocal Rank Fusion) - default
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- Score-based (for OP#4 global-IDF)
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- **Features**:
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- Deduplication by primary key
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- Facet aggregation (sum across shards)
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- `estimatedTotalHits` sum
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- `processingTimeMs` max
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- **Status**: ✅ Implemented
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### 7. HTTP Endpoint (`search_handler`)
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- **Location**: `crates/miroir-proxy/src/routes/search.rs:163-686`
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- **Route**: `POST /search/:index`
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- **Features**:
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- DFS query-then-fetch (OP#4 global-IDF preflight)
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- Session pinning (plan §13.6)
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- Query coalescing (plan §13.10)
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- X-Miroir-Degraded header
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- Settings version headers
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- **Status**: ✅ Implemented
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### 8. HTTP Client (`HttpClient::search_node`)
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- **Location**: `crates/miroir-proxy/src/client.rs:64-136`
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- **Logic**: POST to `/indexes/{uid}/search` on Meilisearch nodes
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- **Features**:
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- Master key authentication
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- Timeout handling
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- Error handling
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- **Status**: ✅ Implemented
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## Acceptance Tests (10/10 Passed)
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- ✅ Unique-keyword search returns exactly 1 hit (deduplication)
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- ✅ Facet counts sum correctly across shards
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- ✅ Paging: 5 pages of 10 = single limit=50 order, no dupes/gaps
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- ✅ Node down with RF=2: search still covers all shards
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- ✅ Group down: search uses fallback, not degraded
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- ✅ X-Miroir-Degraded header includes actual shard IDs
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- ✅ Full integration test (hits, facets, metadata)
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- ✅ showRankingScore injected unconditionally
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- ✅ limit is offset + limit for coordinator pagination
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- ✅ Degraded header format
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## Integration with Phase 5 Features
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The scatter plan cleanly separates routing decisions for future Phase 5 features:
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- **Hedging** (§13.2): `ScatterPlan.hedging_eligible` flag
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- **Adaptive replica selection** (§13.3): `replica_selector` parameter
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- **Query coalescing** (§13.10): Integrated in search_handler
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