# Delta-Behavior Architecture Decision Records This directory contains the Architecture Decision Records (ADRs) for implementing Delta-Behavior in RuVector - a delta-first approach to incremental vector updates. ## Overview Delta-Behavior transforms RuVector into a **delta-first vector database** where all updates are expressed as incremental changes (deltas) rather than full vector replacements. This approach provides: - **10-100x bandwidth reduction** for sparse updates - **Full temporal history** with point-in-time queries - **CRDT-based conflict resolution** for concurrent updates - **Lazy index repair** with quality bounds - **Multi-tier compression** (5-50x storage reduction) ## ADR Index | ADR | Title | Status | Summary | |-----|-------|--------|---------| | [ADR-DB-001](ADR-DB-001-delta-behavior-core-architecture.md) | Delta Behavior Core Architecture | Proposed | Delta-first architecture with layered composition | | [ADR-DB-002](ADR-DB-002-delta-encoding-format.md) | Delta Encoding Format | Proposed | Hybrid sparse-dense with adaptive switching | | [ADR-DB-003](ADR-DB-003-delta-propagation-protocol.md) | Delta Propagation Protocol | Proposed | Reactive push with backpressure | | [ADR-DB-004](ADR-DB-004-delta-conflict-resolution.md) | Delta Conflict Resolution | Proposed | CRDT-based with causal ordering | | [ADR-DB-005](ADR-DB-005-delta-index-updates.md) | Delta Index Updates | Proposed | Lazy repair with quality bounds | | [ADR-DB-006](ADR-DB-006-delta-compression-strategy.md) | Delta Compression Strategy | Proposed | Multi-tier compression pipeline | | [ADR-DB-007](ADR-DB-007-delta-temporal-windows.md) | Delta Temporal Windows | Proposed | Adaptive windows with compaction | | [ADR-DB-008](ADR-DB-008-delta-wasm-integration.md) | Delta WASM Integration | Proposed | Component model with shared memory | | [ADR-DB-009](ADR-DB-009-delta-observability.md) | Delta Observability | Proposed | Delta lineage tracking with OpenTelemetry | | [ADR-DB-010](ADR-DB-010-delta-security-model.md) | Delta Security Model | Proposed | Signed deltas with capability tokens | ## Architecture Diagram ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ DELTA-BEHAVIOR ARCHITECTURE │ └─────────────────────────────────────────────────────────────────────────────┘ ┌───────────────┐ │ Delta API │ ADR-001 │ (apply, get, │ │ rollback) │ └───────┬───────┘ │ ┌─────────────────┼─────────────────┐ │ │ │ v v v ┌───────────────┐ ┌───────────────┐ ┌───────────────┐ │ Security │ │ Propagation │ │ Observability │ │ (signed, │ │ (reactive, │ │ (lineage, │ │ capability) │ │ backpressure)│ │ tracing) │ │ ADR-010 │ │ ADR-003 │ │ ADR-009 │ └───────┬───────┘ └───────┬───────┘ └───────┬───────┘ │ │ │ └─────────────────┼─────────────────┘ │ ┌───────v───────┐ │ Conflict │ ADR-004 │ Resolution │ │ (CRDT, VC) │ └───────┬───────┘ │ ┌─────────────────┼─────────────────┐ │ │ │ v v v ┌───────────────┐ ┌───────────────┐ ┌───────────────┐ │ Encoding │ │ Temporal │ │ Index │ │ (sparse/ │ │ Windows │ │ Updates │ │ dense/RLE) │ │ (adaptive) │ │ (lazy repair) │ │ ADR-002 │ │ ADR-007 │ │ ADR-005 │ └───────┬───────┘ └───────┬───────┘ └───────┬───────┘ │ │ │ └─────────────────┼─────────────────┘ │ ┌─────────────────┼─────────────────┐ │ │ │ v v v ┌───────────────┐ ┌───────────────┐ ┌───────────────┐ │ Compression │ │ WASM │ │ Storage │ │ (LZ4/Zstd/ │ │ Integration │ │ Layer │ │ quantize) │ │ (component │ │ (delta log, │ │ ADR-006 │ │ model) │ │ checkpoint) │ │ │ │ ADR-008 │ │ ADR-001 │ └───────────────┘ └───────────────┘ └───────────────┘ ``` ## Key Design Decisions ### 1. Delta-First Storage (ADR-001) All mutations are stored as deltas. Full vectors are materialized on-demand by composing delta chains. Checkpoints provide optimization points for composition. ### 2. Hybrid Encoding (ADR-002) Automatic selection between sparse, dense, RLE, and dictionary encoding based on delta characteristics. Achieves 1-10x encoding-level compression. ### 3. Reactive Propagation (ADR-003) Push-based delta distribution with explicit backpressure. Causal ordering via vector clocks ensures consistency. ### 4. CRDT Merging (ADR-004) Per-dimension version tracking with configurable conflict resolution strategies (LWW, max, average, custom). ### 5. Lazy Index Repair (ADR-005) Index updates are deferred until quality degrades below bounds. Background repair maintains recall targets. ### 6. Multi-Tier Compression (ADR-006) Encoding -> Quantization -> Entropy coding -> Batch optimization. Achieves 5-50x total compression. ### 7. Adaptive Windows (ADR-007) Dynamic window sizing based on load. Automatic compaction reduces long-term storage. ### 8. WASM Component Model (ADR-008) Clean interface contracts for browser deployment. Shared memory patterns for high-throughput scenarios. ### 9. Lineage Tracking (ADR-009) Full delta provenance with OpenTelemetry integration. Point-in-time reconstruction and blame queries. ### 10. Signed Deltas (ADR-010) Ed25519 signatures for integrity. Capability tokens for fine-grained authorization. ## Performance Targets | Metric | Target | Notes | |--------|--------|-------| | Delta application | < 50us | Faster than full write | | Composition (100 deltas) | < 1ms | With checkpoint | | Network reduction (sparse) | > 10x | For <10% dimension changes | | Storage compression | 5-50x | With full pipeline | | Index recall degradation | < 5% | With lazy repair | | Security overhead | < 100us | Signature verification | ## Implementation Phases ### Phase 1: Core Infrastructure - Delta types and storage (ADR-001) - Basic encoding (ADR-002) - Simple checkpointing ### Phase 2: Distribution - Propagation protocol (ADR-003) - Conflict resolution (ADR-004) - Causal ordering ### Phase 3: Index Integration - Lazy repair (ADR-005) - Quality monitoring - Incremental HNSW ### Phase 4: Optimization - Multi-tier compression (ADR-006) - Temporal windows (ADR-007) - Adaptive policies ### Phase 5: Platform - WASM integration (ADR-008) - Observability (ADR-009) - Security model (ADR-010) ## Dependencies | Component | Crate | Purpose | |-----------|-------|---------| | Signatures | `ed25519-dalek` | Delta signing | | Compression | `lz4_flex`, `zstd` | Entropy coding | | Tracing | `opentelemetry` | Observability | | Async | `tokio` | Propagation | | Serialization | `bincode`, `serde` | Wire format | ## Related ADRs - **ADR-001**: Ruvector Core Architecture - **ADR-CE-002**: Incremental Coherence Computation - **ADR-005**: WASM Runtime Integration - **ADR-007**: Security Review & Technical Debt ## References 1. Shapiro, M., et al. "Conflict-free Replicated Data Types." SSS 2011. 2. Kleppmann, M. "Designing Data-Intensive Applications." O'Reilly, 2017. 3. Malkov, Y., & Yashunin, D. "Efficient and robust approximate nearest neighbor search using HNSW graphs." 4. OpenTelemetry Specification. https://opentelemetry.io/docs/specs/ 5. WebAssembly Component Model. https://component-model.bytecodealliance.org/ --- **Authors**: RuVector Architecture Team **Date**: 2026-01-28 **Status**: Proposed