ebc300355c
Implement the search read path with scatter-gather + merge + group selection: 1. Group-unavailability fallback: When a shard has no available replica in the primary group, the Fallback policy tries other replica groups before failing. This provides full results (not degraded) when an alternate group is healthy. 2. X-Miroir-Degraded header: Now includes actual shard IDs in the format "X-Miroir-Degraded: shards=3,7,11" instead of just "partial". 3. Acceptance tests for P2.3: - Unique-keyword search deduplicates correctly (RRF) - Facet counts sum across shards - Paging with no dupes/gaps - Node down with RF=2 still covers all shards - Group down falls back to other group (not degraded) - Degraded header includes actual shard IDs Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> |
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| benches | ||
| charts/miroir | ||
| crates | ||
| docs | ||
| tests/benches/score-comparability | ||
| .editorconfig | ||
| .gitignore | ||
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| Cargo.toml | ||
| CHANGELOG.md | ||
| clippy.toml | ||
| LICENSE | ||
| miroir.yaml | ||
| README.md | ||
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Miroir
Multi-node Index Replication Orchestrator, Integrated Rebalancing
Miroir is a RAID-like orchestration layer for Meilisearch. It stripes a large index across a fleet of small-RAM Meilisearch nodes with a configurable replication factor, fans out search queries across all shards, and rebalances shard assignments when nodes are added or removed — all using the Meilisearch Community Edition.
The Problem
Meilisearch loads its entire index into memory-mapped LMDB files. A large index that exceeds a single server's available RAM cannot run on that server. The Enterprise Edition's native sharding is gated behind a commercial license. Miroir solves this without it.
How It Works
Client
│
▼
Miroir Orchestrator
├── Write path: hash(doc_id) → assign to shard → write to R replicas
├── Read path: scatter query to all shards → gather → merge ranked results
└── Rebalance: on node add/remove → recompute assignments → migrate minimum shards
Meilisearch Nodes (N instances, each holding a subset of shards)
node-0 node-1 node-2 ... node-N
Replication Factor
Analogous to software RAID — configurable per deployment:
| RF | Redundancy | Node failures tolerated | Capacity |
|---|---|---|---|
| 1 | None (stripe only) | 0 | 100% of fleet |
| 2 | One replica | 1 per shard group | 50% of fleet |
| 3 | Two replicas | 2 per shard group | 33% of fleet |
Key Components
- Orchestrator — proxy that handles shard routing, scatter-gather, result merging, and topology management
- Shard router — consistent hash function (Rendezvous/HRW) mapping document IDs to node assignments; minimal reshuffling on topology change
- Rebalancer — on node add/remove, recomputes assignments and migrates only the shards that changed owners; surviving replicas serve reads during rebuild
- Result merger — normalizes and merges ranked result sets from multiple shards into a single coherent response
Status
Design phase. See docs/ for architecture detail.