No description
b14db53775
Verified Phase 4 (Topology Operations) is complete: Chaos Tests (22/22 passing): - chaos_add_node_mid_indexing — add node during indexing, all docs readable - chaos_drain_node_while_querying — drain during queries, zero failures - chaos_add_replica_group_while_querying — add group, existing groups unaffected - chaos_rebalance_optimal_movement — ≤2×(1/4) doc movement for 3→4 nodes - chaos_restart_node_mid_rebalance — failure during rebalance, resume on recovery - chaos_rendezvous_determinism — rendezvous hash consistency - chaos_cannot_remove_last_node — safety guard for last node - chaos_cannot_remove_last_group — safety guard for last group - Plus 14 cutover_race tests for dual-write safety Implementation Complete: - Rebalancer with add/remove/drain node and group operations - MigrationCoordinator with dual-write + delta pass - HttpMigrationExecutor for HTTP-based document migration - Admin API endpoints (POST/DELETE /_miroir/nodes, /_miroir/replica_groups) - CLI commands (miroir-ctl node add/remove/drain/list, rebalance status) Test Results: - Library tests: 262 passed - Chaos tests: 22 passed - Total: 284 tests passed Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> |
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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.