Multi-Tier Replication

[makr-code]

Context

This issue implements the roadmap item 'Multi-Tier Replication' for the replication domain. It is sourced from the consolidated roadmap under 🟢 Low Priority — Future (v1.9.0+) and targets milestone v1.8.0.

Primary detail section: Multi-Tier Replication

Goal

Deliver the scoped changes for Multi-Tier Replication in src/replication/ and complete the linked detail section in a release-ready state for v1.8.0.

Detailed Scope

Multi-Tier Replication

Priority: Low
Target Version: v1.8.0

Hierarchical replication with different consistency and durability tiers.

Features:

• Tier 1: Strong consistency, high durability (3+ replicas)
• Tier 2: Eventual consistency, moderate durability (2 replicas)
• Tier 3: Best-effort, low durability (1 replica, async)
• Per-collection tier assignment
• Automatic tier promotion/demotion based on access patterns

Architecture:

class MultiTierReplicationManager {
public:
    enum ReplicationTier {
        TIER_1_CRITICAL,    // 3+ replicas, sync, <10ms
        TIER_2_STANDARD,    // 2 replicas, semi-sync, <50ms
        TIER_3_ARCHIVAL     // 1 replica, async, no guarantee
    };
    
    struct TierConfig {
        ReplicationTier tier;
        uint32_t replica_count;
        ReplicationMode mode;
        uint32_t max_latency_ms;
        uint32_t min_availability_percent;
    };
    
    // Assign collection to tier
    void assignTier(const std::string& collection, ReplicationTier tier);
    
    // Automatic tier adjustment based on access patterns
    void enableAutoTiering(bool enabled);
    
    // Get current tier for collection
    ReplicationTier getTier(const std::string& collection) const;
};

// Example: Multi-tier replication
MultiTierReplicationManager multi_tier;

// Tier assignments
multi_tier.assignTier("financial_transactions", ReplicationTier::TIER_1_CRITICAL);
multi_tier.assignTier("user_profiles", ReplicationTier::TIER_2_STANDARD);
multi_tier.assignTier("audit_logs", ReplicationTier::TIER_3_ARCHIVAL);

// Auto-tiering based on access
multi_tier.enableAutoTiering(true);  // Hot data → Tier 1, Cold data → Tier 3

---

Acceptance Criteria

• Tier 1: Strong consistency, high durability (3+ replicas)
• Tier 2: Eventual consistency, moderate durability (2 replicas)
• Tier 3: Best-effort, low durability (1 replica, async)
• Per-collection tier assignment
• Automatic tier promotion/demotion based on access patterns

Relationships

• Roadmap row: Security analysis and detection framework for LLM and LoRa adapter attack vectors #258 (🟢 Low Priority — Future (v1.9.0+))
• Depends on: none identified during generation.
• Part of: consolidated roadmap delivery tracking.

References

• src/ROADMAP.md
• src/replication/FUTURE_ENHANCEMENTS.md#multi-tier-replication
• Source key: roadmap:258:replication:v1.8.0:multi-tier-replication

Generated from the consolidated source roadmap. Keep the roadmap and issue in sync when scope changes.