Skip to content
HeliosDB HeliosDB Full

HeliosDB Architecture Compliance Checklist

HeliosDB Architecture Compliance Checklist

This is a living document tracking compliance with design specifications. Review and update weekly as implementation progresses.

Last Updated: 2025-10-10 Status: 🔴 Not Started

1. Core Architecture

1.1 Compute-Storage Separation

  • Compute nodes have no direct disk access to user data
  • Storage nodes expose data only through HIDB protocol
  • Clear trait boundaries between tiers
  • No circular dependencies between heliosdb-compute and heliosdb-storage

Status: 🔴 Not Implemented Blocker: None

1.2 Network Layer

RDMA/RoCEv2

  • RDMA transport implemented OR
  • TCP fallback with documented migration path
  • Latency < 10μs for RDMA operations (when using RDMA)
  • Kernel-bypass verified with benchmarks

Status: 🔴 Not Implemented Blocker: Need to choose TCP-first vs RDMA-first strategy

HIDB Protocol

  • Protobuf schemas defined for all message types:
    • PredicatePushdownRequest
    • FilteredResultSet
    • VectorSearchRequest
    • CacheInvalidationNotice
    • ReplicationDataStream
  • gRPC service definitions complete
  • Protocol versioning implemented
  • Backward compatibility tested

Status: 🔴 Not Implemented Blocker: Need protobuf schema design

1.3 Metadata Service

Raft Consensus

  • etcd/raft library integrated
  • Raft log persisted to RocksDB
  • gRPC transport for Raft messages
  • Snapshot/restore mechanism
  • Leader election functional
  • 3-node cluster tested
  • 5-node cluster tested
  • Network partition recovery tested

Status: 🔴 Not Implemented Blocker: None - critical path item

Managed State

  • Shard topology mapping implemented
  • Schema storage (DDL artifacts)
  • Node health tracking
  • Configuration management
  • Cache invalidation notifications

Status: 🔴 Not Implemented Blocker: Raft implementation

2. Data Organization

2.1 Storage Engine

LSM-Tree

  • Write path: CommitLog → Memtable → SSTable
  • Read path with Bloom filter optimization
  • Compaction strategy (STCS or LCS)
  • Configurable per-table compaction
  • WAL replay on recovery
  • Crash recovery tested

Status: 🔴 Not Implemented Decision Needed: RocksDB vs custom implementation

Tombstones

  • DELETE operations write tombstones
  • gc_grace_seconds configurable
  • Tombstone garbage collection during compaction
  • Distributed delete consistency verified

Status: 🔴 Not Implemented Blocker: LSM implementation

2.2 Sharding

Consistent Hashing

  • Hash function chosen (Jump Hash recommended)
  • compute_shard_id() implemented
  • Hash ring topology maintained in metadata service
  • Shard assignment deterministic
  • Even distribution verified with tests

Status: 🔴 Not Implemented Blocker: None

Replication

  • Primary + mirror shard pairs
  • Synchronous replication (RPO = 0)
  • Witness-based quorum for failover
  • Split-brain prevention verified
  • Failover time < 10 seconds tested

Status: 🔴 Not Implemented Blocker: Sharding implementation

Rebalancing

  • Data migration protocol defined
  • Minimal data movement during node addition
  • Backpressure during migration
  • Online rebalancing (no downtime)

Status: 🔴 Not Implemented Blocker: Sharding implementation

2.3 Partitioning

  • RANGE partitioning
  • LIST partitioning
  • HASH partitioning
  • COMPOSITE partitioning
  • Partition pruning in query optimizer
  • DDL syntax: PARTITION BY clause

Status: 🔴 Not Implemented Blocker: Query engine

2.4 Hybrid Columnar Compression (HCC)

NOTE: Recommended to defer to Phase 2+

  • Compression Unit (CU) data structure
  • Columnar layout within CU
  • LZ4 compression algorithm
  • ZSTD compression algorithm
  • Dictionary encoding
  • WAREHOUSE_OPTIMIZED mode
  • ARCHIVE_OPTIMIZED mode
  • Background migration from row to HCC format

Status: 🔴 Not Implemented (Deferred) Blocker: Core storage engine

3. Query Execution

3.1 Predicate Pushdown

  • WHERE clause analysis in optimizer
  • Predicate serialization to storage nodes
  • Column projection (SELECT clause optimization)
  • Row-oriented predicate evaluation
  • HCC-aware predicate evaluation (decompress only needed columns)
  • Supported predicates:
    • Equality (=)
    • Comparison (>, <, >=, <=)
    • Range (BETWEEN)
    • Membership (IN)
    • Pattern (LIKE)
    • Boolean (AND, OR, NOT)

Status: 🔴 Not Implemented Blocker: Query engine and storage engine

3.2 Online Aggregation Engine

NOTE: Advanced feature, defer to Phase 3+

  • ONLINE AGGREGATE DDL syntax
  • DELTA column type
  • Semantic concurrency control
  • Commutative operation detection
  • Conflict-free write path
  • On-the-fly read path with delta application
  • Background consolidation process

Status: 🔴 Not Implemented (Deferred) Blocker: Core transactional engine

3.3 Distributed Query Execution

  • Query parsing
  • Distributed query planning
  • Shard-aware query routing
  • Storage task dispatch
  • Partial result aggregation
  • Multi-shard parallelism
  • Intra-shard parallelism
  • Result streaming to client

Status: 🔴 Not Implemented Blocker: Network layer and storage engine

4. Vector Database Integration

4.1 VECTOR Data Type

  • Type system supports VECTOR(n)
  • DDL: CREATE TABLE with VECTOR column
  • TOAST-like storage implementation:
    • Inline storage for small vectors (<2KB)
    • Out-of-line storage for large vectors
    • PLAIN storage mode
    • EXTERNAL storage mode
  • ALTER COLUMN SET STORAGE syntax

Status: 🔴 Not Implemented Blocker: Type system

4.2 Vector Indexing

HNSW

  • Graph construction algorithm
  • Multi-layer navigation
  • Vector pool in memory
  • Index build process
  • Index persistence
  • Configurable M parameter (edges per node)
  • Configurable ef_construction parameter

Status: 🔴 Not Implemented Decision Needed: Use faiss-rs vs custom implementation

IVF

  • Cluster creation (k-means)
  • Inverted lists
  • Cluster assignment
  • Index build process
  • Configurable nlist parameter
  • Configurable nprobe parameter

Status: 🔴 Not Implemented Blocker: HNSW implementation

  • Bitmap allow-list creation from scalar indexes
  • Filter-aware HNSW traversal
  • Candidate filtering before distance calculation
  • Multi-hop traversal for filtered islands
  • Performance benchmarks:
    • 10% selectivity
    • 1% selectivity
    • 0.1% selectivity
  • Recall metrics (>90% target)

Status: 🔴 Not Implemented Blocker: HNSW implementation and scalar indexes

NOTE: Consider post-filtering as Phase 1 approach

5. Protocol Compatibility

5.1 PostgreSQL Protocol (GOLD)

  • Connection establishment
  • TLS negotiation
  • SCRAM-SHA-256 authentication
  • Simple query protocol
  • Extended query protocol (prepared statements)
  • Parameter binding
  • Cursors
  • Transactions (BEGIN/COMMIT/ROLLBACK)
  • Result set streaming
  • Error codes (SQLSTATE)
  • Data type mappings:
    • INTEGER, BIGINT
    • REAL, DOUBLE PRECISION
    • VARCHAR, TEXT
    • BYTEA
    • TIMESTAMP
    • NUMERIC/DECIMAL
    • VECTOR(n) as custom type

Python Driver Tests:

  • psycopg2: connect, SELECT 1, prepared stmt, tx
  • asyncpg: connect, SELECT 1, prepared stmt, tx
  • SQLAlchemy: connect, ORM operations

Status: 🔴 Not Implemented Priority: CRITICAL - Phase 1 MVP

5.2 MySQL Protocol (GOLD)

  • Connection establishment
  • TLS negotiation
  • caching_sha2_password authentication
  • Text protocol queries
  • Binary protocol (prepared statements)
  • Parameter binding
  • Autocommit semantics
  • Transactions
  • Result set streaming
  • Error codes (MySQL error numbers)
  • Data type mappings

Python Driver Tests:

  • mysql-connector-python: connect, query, tx
  • PyMySQL: connect, query, tx
  • SQLAlchemy: connect, ORM operations

Status: 🔴 Not Implemented (Phase 1.5) Priority: HIGH

5.3 HTTP API Protocols (SILVER)

Snowflake REST API

  • Session creation endpoint
  • Query submission endpoint
  • Result fetch endpoint
  • Query cancellation
  • TLS + password auth
  • JSON response formatting

Python Driver Tests:

  • snowflake-connector-python: connect, query, fetchall

Status: 🔴 Not Implemented (Phase 2) Priority: MEDIUM

Databricks SQL API

  • HTTP/Thrift subset
  • Token authentication
  • Query execution
  • Result fetching

Python Driver Tests:

  • databricks-sql-connector: connect, query, fetchmany

Status: 🔴 Not Implemented (Phase 2) Priority: MEDIUM

Pinecone API

  • Index creation
  • Vector upsert
  • Top-k query
  • Filtered query
  • API key authentication

Python Driver Tests:

  • pinecone-client: create index, upsert, query with filter

Status: 🔴 Not Implemented (Phase 2) Priority: MEDIUM

5.4 Enterprise Protocols (BRONZE)

NOTE: Only implement if customer demand exists

SQL Server TDS

  • Connection
  • Password auth
  • Simple queries
  • Parameter binding

Status: 🔴 Not Implemented (Phase 3+) Priority: LOW

DB2 DRDA

  • Connection
  • Password auth
  • Simple queries

Status: 🔴 Not Implemented (Phase 3+) Priority: LOW

Oracle Net/TTC

  • Connection
  • Password auth
  • SELECT 1 FROM DUAL
  • Parameter binding

Status: 🔴 Not Implemented (Phase 3+) Priority: LOW

6. Quality Standards

6.1 Testing

  • Unit test coverage ≥ 80%
  • Integration tests for all tiers
  • Protocol compliance tests in CI
  • Performance benchmarks
  • Chaos engineering tests
  • Fuzz testing for protocol parsers

Status: 🔴 No tests exist Priority: CRITICAL - must start immediately

6.2 Security

  • TLS 1.3 for all connections
  • SCRAM-SHA-256 for PostgreSQL
  • Argon2 password hashing
  • JWT token management
  • SQL injection prevention verified
  • Penetration testing completed
  • Security audit by external firm

Status: 🔴 Not Implemented Priority: HIGH

6.3 Observability

  • Structured logging (tracing crate)
  • Prometheus metrics export
  • Distributed tracing (OpenTelemetry)
  • Health check endpoints (/health/liveness, /health/readiness)
  • Query explain plans
  • Query statistics tracking

Status: 🔴 Not Implemented Priority: MEDIUM

6.4 Documentation

  • rustdoc on all public APIs
  • Architecture Decision Records (ADRs)
  • Deployment guide
  • Performance tuning guide
  • Troubleshooting guide
  • Protocol compatibility guide
  • SQL dialect differences documented

Status: 🔴 Not Started Priority: MEDIUM

7. Performance Benchmarks

7.1 Latency Targets

  • RDMA operation latency < 10μs (if using RDMA)
  • Point query latency P99 < 10ms
  • Range query latency P99 < 100ms
  • Vector search latency P99 < 50ms
  • Transaction commit latency P99 < 20ms

Status: 🔴 No benchmarks exist Priority: HIGH (after basic functionality)

7.2 Throughput Targets

  • Write throughput > 100K ops/sec (per node)
  • Read throughput > 500K ops/sec (per node)
  • Linear scalability with node count (tested up to 10 nodes)

Status: 🔴 No benchmarks exist Priority: MEDIUM

Review Schedule

  • Weekly: Update this checklist during team meetings
  • Monthly: Formal compliance review with Reviewer Agent
  • Quarterly: External architecture review

Next Review: 2025-10-17 (weekly update) Next Formal Review: 2026-01-10 (after Phase 1 completion)

Legend

  • 🔴 Not Started
  • 🟡 In Progress
  • 🟢 Complete
  • ⚪ Deferred/Optional

Maintained by: Reviewer Agent (HeliosDB Hive Mind) Last Updated: 2025-10-10