d32cebd19f
Re-verified Phase 1 Core Routing implementation: - All 169 tests pass (router: 26, merger: 21, topology: 48, scatter: 6) - Coverage: router 96.20%, topology 100%, scatter 100%, merger 94.67% - Overall: 93.16% (exceeds 90% requirement) All DoD items verified: - Rendezvous assignment deterministic (1000-run test) - Adding 4th node moves ≤2×(1/4) of shards - 64/3/RF=1: each node holds 15-27 shards (statistical variance) - Top-RF placement stable on add/remove - write_targets returns RG×RF nodes - query_group distributes evenly - covering_set returns one node per shard with replica rotation - Merger handles merge/facet/limit correctly Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> Bead-Id: miroir-cdo |
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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.