# Samyama Graph Database - Requirements Specification

## 1. Executive Summary

Samyama is a high-performance, distributed graph database designed to provide in-memory graph processing capabilities with persistent storage, multi-tenancy support, and Redis protocol compatibility.

## 2. Core Requirements

### 2.1 Distributed Architecture
- **REQ-DIST-001**: The system MUST support distributed deployment across multiple nodes
- **REQ-DIST-002**: The system MUST provide automatic data sharding across nodes
- **REQ-DIST-003**: The system MUST support horizontal scaling (add/remove nodes dynamically)
- **REQ-DIST-004**: The system MUST implement fault tolerance with automatic failover
- **REQ-DIST-005**: The system MUST maintain data consistency across distributed nodes
- **REQ-DIST-006**: The system MUST support replication for high availability

### 2.2 Property Graph Model
- **REQ-GRAPH-001**: The system MUST implement the property graph data model
- **REQ-GRAPH-002**: The system MUST support nodes (vertices) with labels
- **REQ-GRAPH-003**: The system MUST support edges (relationships) with types
- **REQ-GRAPH-004**: The system MUST support properties on both nodes and edges
- **REQ-GRAPH-005**: Properties MUST support multiple data types:
  - String
  - Integer
  - Float
  - Boolean
  - Date/Time
  - Array
  - Map/Object
- **REQ-GRAPH-006**: The system MUST support multiple labels per node
- **REQ-GRAPH-007**: The system MUST support directed edges
- **REQ-GRAPH-008**: The system MUST allow multiple edges between the same pair of nodes

### 2.3 OpenCypher Query Language
- **REQ-CYPHER-001**: The system MUST support OpenCypher query language
- **REQ-CYPHER-002**: The system MUST implement OpenCypher pattern matching
- **REQ-CYPHER-003**: The system MUST support CRUD operations via Cypher:
  - CREATE
  - MATCH
  - MERGE
  - DELETE
  - SET
  - REMOVE
- **REQ-CYPHER-004**: The system MUST support Cypher aggregation functions
- **REQ-CYPHER-005**: The system MUST support Cypher path queries
- **REQ-CYPHER-006**: The system MUST support variable-length path patterns
- **REQ-CYPHER-007**: The system MUST support Cypher WHERE clauses and filtering
- **REQ-CYPHER-008**: The system MUST support Cypher ORDER BY and LIMIT clauses
- **REQ-CYPHER-009**: The system MUST provide query optimization for Cypher queries

### 2.4 Multi-Tenancy
- **REQ-TENANT-001**: The system MUST support multiple isolated tenants on a single cluster
- **REQ-TENANT-002**: Each tenant MUST have isolated data (logical separation)
- **REQ-TENANT-003**: The system MUST support tenant-specific resource quotas:
  - Memory limits
  - Storage limits
  - Query execution time limits
  - Connection limits
- **REQ-TENANT-004**: The system MUST provide tenant-level authentication and authorization
- **REQ-TENANT-005**: The system MUST prevent cross-tenant data access
- **REQ-TENANT-006**: The system MUST support tenant-level monitoring and metrics
- **REQ-TENANT-007**: The system MUST allow dynamic tenant creation and deletion
- **REQ-TENANT-008**: The system MUST support tenant-level backup and restore

### 2.5 Redis Protocol Compatibility
- **REQ-REDIS-001**: The system MUST implement Redis protocol (RESP)
- **REQ-REDIS-002**: The system MUST support Redis client connections
- **REQ-REDIS-003**: The system MUST support Redis authentication mechanisms
- **REQ-REDIS-004**: The system MUST provide Redis-compatible graph commands
- **REQ-REDIS-005**: The system MUST support Redis clustering protocol for distributed operations
- **REQ-REDIS-006**: The system MUST be compatible with standard Redis client libraries
- **REQ-REDIS-007**: The system MUST support Redis pipelining for batch operations
- **REQ-REDIS-008**: The system MUST support Redis pub/sub for notifications (optional enhancement)

### 2.6 In-Memory Storage
- **REQ-MEM-001**: The system MUST store graph data primarily in memory
- **REQ-MEM-002**: The system MUST provide efficient memory management and allocation
- **REQ-MEM-003**: The system MUST support memory-optimized data structures
- **REQ-MEM-004**: The system MUST provide memory usage monitoring and reporting
- **REQ-MEM-005**: The system MUST implement memory eviction policies when limits are reached
- **REQ-MEM-006**: The system MUST support configurable memory limits per tenant
- **REQ-MEM-007**: The system MUST optimize memory layout for cache locality

### 2.7 Persistence to Disk
- **REQ-PERSIST-001**: The system MUST support persistence of in-memory data to disk
- **REQ-PERSIST-002**: The system MUST implement Write-Ahead Logging (WAL) for durability
- **REQ-PERSIST-003**: The system MUST support configurable persistence strategies:
  - Synchronous (immediate write)
  - Asynchronous (batched writes)
  - Snapshot-based (periodic checkpoints)
- **REQ-PERSIST-004**: The system MUST support automatic recovery from disk on restart
- **REQ-PERSIST-005**: The system MUST ensure data consistency between memory and disk
- **REQ-PERSIST-006**: The system MUST support incremental persistence (delta updates)
- **REQ-PERSIST-007**: The system MUST support snapshot creation for backup purposes
- **REQ-PERSIST-008**: The system MUST provide configurable persistence intervals
- **REQ-PERSIST-009**: The system MUST support compression for persisted data

## 3. Optional Requirements

### 3.1 RDF Support (Foundation Complete)
- **REQ-RDF-001**: The system SHOULD support Resource Description Framework (RDF) data model
- **REQ-RDF-002**: The system SHOULD support RDF triples (subject-predicate-object)
- **REQ-RDF-003**: The system SHOULD support RDF/XML, Turtle, N-Triples serialization formats
- **REQ-RDF-004**: The system SHOULD support named graphs (quad store)
- **REQ-RDF-005**: The system SHOULD support RDF Schema (RDFS) semantics
- **REQ-RDF-006**: The system SHOULD provide mapping between property graph and RDF models
- **REQ-RDF-007**: The system SHOULD support OWL (Web Ontology Language) reasoning (basic)

### 3.2 SPARQL Support (Parser Complete)
- **REQ-SPARQL-001**: The system SHOULD support SPARQL 1.1 query language
- **REQ-SPARQL-002**: The system SHOULD implement SPARQL protocol for HTTP
- **REQ-SPARQL-003**: The system SHOULD support SPARQL query forms:
  - SELECT
  - CONSTRUCT
  - ASK
  - DESCRIBE
- **REQ-SPARQL-004**: The system SHOULD support SPARQL UPDATE operations
- **REQ-SPARQL-005**: The system SHOULD support SPARQL filtering and constraints
- **REQ-SPARQL-006**: The system SHOULD support SPARQL aggregates
- **REQ-SPARQL-007**: The system SHOULD support SPARQL federation (SERVICE keyword)
- **REQ-SPARQL-008**: The system SHOULD optimize SPARQL queries for in-memory execution

### 3.3 Auto-Embed Pipelines (Completed)
- **REQ-RAG-001**: The system MUST support automatic vector embedding generation for text properties
- **REQ-RAG-002**: The system MUST support tenant-level configuration for LLM providers (OpenAI, Ollama, etc.)
- **REQ-RAG-003**: The system MUST implement an event-driven background pipeline for embedding generation
- **REQ-RAG-004**: The system MUST automatically update vector indices when source text changes
- **REQ-RAG-005**: The system MUST support configurable chunking and overlap strategies
- **REQ-RAG-006**: The system MUST ensure embedding generation does not block write operations (async)

### 3.4 Natural Language Querying (Completed)
- **REQ-NLQ-001**: The system SHOULD support querying graph data using natural language text
- **REQ-NLQ-002**: The system SHOULD translate natural language to valid OpenCypher queries
- **REQ-NLQ-003**: The system MUST support tenant-specific configuration for NLQ providers and models
- **REQ-NLQ-004**: The system MUST inject tenant schema (labels/edges) into the translation context
- **REQ-NLQ-005**: The system SHOULD restrict generated queries to read-only operations by default
- **REQ-NLQ-006**: The system MUST return the generated Cypher query alongside results for verification

### 3.5 Agentic Enrichment (Completed)
- **REQ-AGENT-001**: The system MUST support autonomous agents triggered by graph events (NodeCreated, PropertySet)
- **REQ-AGENT-002**: The system MUST support tenant-level configuration of agent policies and triggers
- **REQ-AGENT-003**: Agents MUST be able to execute tools (e.g., Web Search, API calls)
- **REQ-AGENT-004**: Agents MUST be able to read and write to the graph (enrichment)
- **REQ-AGENT-005**: The system MUST provide a framework for defining and registering new tools
- **REQ-AGENT-006**: Agent execution MUST be asynchronous and non-blocking to the main query path

## 4. Performance Requirements

### 4.1 Query Performance
- **REQ-PERF-001**: The system MUST execute simple pattern matches (1-2 hops) in < 10ms (p99)
- **REQ-PERF-002**: The system MUST support at least 10,000 read queries per second per node
- **REQ-PERF-003**: The system MUST support at least 1,000 write operations per second per node
- **REQ-PERF-004**: The system MUST scale linearly with additional nodes (up to reasonable limits)

### 4.2 Memory Performance
- **REQ-PERF-005**: The system MUST support graphs with billions of nodes and edges
- **REQ-PERF-006**: The system MUST minimize memory overhead (< 20% of raw data size)
- **REQ-PERF-007**: The system MUST provide sub-millisecond traversal times for cached paths

### 4.3 Persistence Performance
- **REQ-PERF-008**: The system MUST support configurable durability vs. performance trade-offs
- **REQ-PERF-009**: Asynchronous persistence MUST NOT impact read performance by > 5%
- **REQ-PERF-010**: Recovery time MUST be proportional to the size of WAL, not total data size

## 5. Scalability Requirements

- **REQ-SCALE-001**: The system MUST support scaling from 1 to 100+ nodes
- **REQ-SCALE-002**: The system MUST support datasets from MB to TB scale
- **REQ-SCALE-003**: The system MUST support 1,000+ concurrent connections per node
- **REQ-SCALE-004**: The system MUST support 100+ tenants on a single cluster

## 6. Availability and Reliability

- **REQ-AVAIL-001**: The system MUST provide 99.9% uptime SLA
- **REQ-AVAIL-002**: The system MUST recover from single node failure in < 30 seconds
- **REQ-AVAIL-003**: The system MUST not lose committed data in case of single node failure
- **REQ-AVAIL-004**: The system MUST support rolling upgrades without downtime
- **REQ-AVAIL-005**: The system MUST provide automatic health checks and monitoring

## 7. Security Requirements

- **REQ-SEC-001**: The system MUST support authentication (username/password minimum)
- **REQ-SEC-002**: The system MUST support TLS/SSL for client connections
- **REQ-SEC-003**: The system MUST support role-based access control (RBAC)
- **REQ-SEC-004**: The system MUST support encryption at rest for persistent data
- **REQ-SEC-005**: The system MUST provide audit logging for security events
- **REQ-SEC-006**: The system MUST prevent injection attacks in query languages

## 8. Operational Requirements

### 8.1 Monitoring and Observability
- **REQ-OPS-001**: The system MUST provide metrics for:
  - Query latency (p50, p95, p99)
  - Throughput (queries per second)
  - Memory usage
  - Disk usage
  - Network I/O
  - Error rates
- **REQ-OPS-002**: The system MUST support integration with standard monitoring tools (Prometheus, Grafana)
- **REQ-OPS-003**: The system MUST provide detailed query execution plans for debugging
- **REQ-OPS-004**: The system MUST provide structured logging

### 8.2 Backup and Recovery
- **REQ-OPS-005**: The system MUST support online backups without service interruption
- **REQ-OPS-006**: The system MUST support point-in-time recovery
- **REQ-OPS-007**: The system MUST support backup to external storage (S3, etc.)
- **REQ-OPS-008**: The system MUST verify backup integrity

### 8.3 Configuration and Management
- **REQ-OPS-009**: The system MUST support configuration via files and environment variables
- **REQ-OPS-010**: The system MUST provide a management API for cluster operations
- **REQ-OPS-011**: The system MUST support dynamic reconfiguration without restart (where possible)

## 9. Compatibility and Integration

- **REQ-COMPAT-001**: The system MUST provide client drivers for major languages:
  - Python
  - Java
  - JavaScript/Node.js
  - Go
  - .NET
- **REQ-COMPAT-002**: The system MUST support deployment on major cloud platforms (AWS, Azure, GCP)
- **REQ-COMPAT-003**: The system MUST support containerized deployment (Docker, Kubernetes)
- **REQ-COMPAT-004**: The system MUST provide REST API in addition to Redis protocol

## 10. Development and Testing Requirements

- **REQ-DEV-001**: The system MUST include comprehensive unit tests (> 80% coverage)
- **REQ-DEV-002**: The system MUST include integration tests for distributed scenarios
- **REQ-DEV-003**: The system MUST include performance benchmarks
- **REQ-DEV-004**: The system MUST include documentation for all APIs and features
- **REQ-DEV-005**: The system MUST use open-source license (Apache 2.0 or similar)

## 11. Technology Stack Considerations

### 11.1 Implementation Considerations
- High-performance language recommended (Rust, C++, or Go)
- Zero-copy serialization for network efficiency
- Lock-free data structures where possible
- SIMD optimizations for traversals
- Custom memory allocators for graph data

### 11.2 Storage Layer Considerations
- Append-only log structure for WAL
- Memory-mapped files for efficient persistence
- Column-oriented storage for properties
- Compressed indices for faster lookups

### 11.3 Network Layer Considerations
- Support for RESP2 and RESP3 protocols
- HTTP/2 for REST API
- gRPC for internal cluster communication

## 12. Future Enhancements (Out of Scope for v1.0)

- ~~Graph algorithms library~~ → **Implemented** (PageRank, BFS, Dijkstra, WCC, SCC, MaxFlow, MST, TriangleCount in `crates/samyama-graph-algorithms/`)
- Time-series graph support → **Foundation** (MVCC versioning with `get_node_at_version`)
- Graph visualization tools
- ~~Machine learning integration (Graph Neural Networks)~~ → **Proposed** (see `docs/GNN_PROPOSAL.md`)
- ~~Multi-model support (document + graph)~~ → **Partial** (RDF + Property Graph dual-model)
- Geospatial query support
- Full-text search integration

## 13. Success Criteria

The system will be considered successful if it:
1. Passes all functional tests for core requirements
2. Meets performance benchmarks for 95% of test scenarios
3. Demonstrates linear scalability up to 10 nodes
4. Provides compatibility with major Redis clients
5. Successfully supports at least 10 concurrent tenants
6. Achieves 99.9% uptime in production testing

## 14. Acceptance Criteria

### Phase 1 - Core Features (Minimum Viable Product)
- Property graph support
- OpenCypher query execution
- Single-node in-memory storage
- Basic persistence (WAL + snapshots)
- Redis protocol support
- Basic authentication

### Phase 2 - Distribution and Multi-Tenancy
- Distributed cluster support
- Multi-tenancy isolation
- Replication and failover
- Resource quotas

### Phase 3 - Optional Features
- RDF data model support
- SPARQL query support
- Advanced security features
- Enhanced monitoring

## 15. Risks and Mitigation

| Risk | Impact | Probability | Mitigation |
|------|--------|-------------|------------|
| Memory scalability limits | High | Medium | Implement efficient memory structures, compression |
| Distributed consistency complexity | High | High | Use proven consensus protocols (Raft/Paxos) |
| OpenCypher compatibility gaps | Medium | Medium | Extensive testing against TCK |
| Redis protocol limitations for graphs | Medium | Low | Design custom graph commands within RESP |
| Performance of optional RDF/SPARQL | Low | Medium | Make optional, optimize separately |

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**Document Version**: 2.0
**Last Updated**: 2026-02-08
**Status**: Active
**Maintainer**: Samyama Graph Database Team
