HeliosDB-Lite v2.4.0 Release Notes¶

Release Date: November 25, 2025 Status: Beta Release Version: v2.4.0-beta

Executive Summary¶

HeliosDB-Lite v2.4.0-beta represents a major milestone in the evolution of our embedded database, successfully implementing Phase 3 features including advanced vector compression, enterprise SQL capabilities, and comprehensive performance optimizations.

Key Achievements¶

✅ Product Quantization: 8-16x vector compression with 95-98% accuracy maintained
✅ Database Branching: Full CREATE/DROP/MERGE BRANCH SQL support
✅ Time-Travel Queries: AS OF TIMESTAMP for historical data access
✅ Materialized Views: Incremental refresh with CPU-aware scheduling
✅ Advanced Compression: FSST string and ALP numeric compression
✅ System Views: PostgreSQL-compatible pg_* views
✅ Test Coverage: 95.1% test pass rate (527/554 tests)
✅ Clean Build: Zero compilation errors

Major Features¶

1. Vector Search Enhancements¶

Product Quantization (PQ)¶

Compression Ratio: 8-16x reduction in memory usage
Accuracy: 95-98% recall maintained
Performance: 5-10x faster search on large datasets
Implementation: K-means++ training with asymmetric distance computation

Quantized HNSW Index¶

Seamless integration with existing vector search
Automatic memory optimization
Configurable compression levels
Real-time compression statistics

2. Database Branching¶

Complete SQL support for database branching:

-- Create development branch
CREATE DATABASE BRANCH dev FROM main AS OF NOW;

-- Work in isolated branch
USE DATABASE BRANCH dev;

-- Merge changes back
MERGE DATABASE BRANCH dev INTO main;

-- Clean up
DROP DATABASE BRANCH dev;

Features: - Zero-copy branching via RocksDB snapshots - Automatic conflict detection - Three-way merge support - Branch metadata tracking

3. Time-Travel Queries¶

Query historical data at any point in time:

-- Query data as it was 1 hour ago
SELECT * FROM users AS OF TIMESTAMP '2025-11-25 08:00:00';

-- Compare current vs historical
SELECT * FROM inventory AS OF TIMESTAMP NOW() - INTERVAL '1 DAY';

-- Use relative timestamps
SELECT * FROM orders AS OF TIMESTAMP NOW() - INTERVAL '7 DAYS';

Capabilities: - 7-day retention by default (configurable) - Automatic garbage collection - Minimal storage overhead - Sub-second time travel

4. Materialized Views with Auto-Refresh¶

Intelligent materialized view management:

-- Create incrementally refreshing view
CREATE MATERIALIZED VIEW sales_summary AS
SELECT date, SUM(amount) as total
FROM sales
GROUP BY date
WITH (
    refresh_interval = '1 HOUR',
    incremental = true
);

-- Manual refresh
REFRESH MATERIALIZED VIEW sales_summary;

Features: - CPU-aware scheduling - Incremental refresh support - Delta change tracking - Automatic dependency resolution

5. Advanced Compression¶

FSST (Fast Static Symbol Table)¶

2-4x compression for string data
500+ MB/sec compression speed
2+ GB/sec decompression speed
Automatic dictionary training

ALP (Adaptive Lossless floating-Point)¶

30-50% compression for numeric data
Preserves full precision
SIMD-accelerated operations
Automatic pattern detection

Performance Improvements¶

Benchmark Results¶

Operation	v2.3.1	v2.4.0	Improvement
Vector Insert	50K/sec	125K/sec	2.5x
Vector Search (1M vectors)	2.5ms	0.5ms	5x
Compression Ratio	N/A	8-16x	New
Memory Usage (1M vectors)	3GB	375MB	8x
Time-Travel Query	N/A	<100ms	New
Branch Creation	N/A	<10ms	New

Breaking Changes¶

API Changes¶

Database renamed to EmbeddedDatabase for clarity
Vector index configuration now requires explicit PQ settings
Some internal modules reorganized (shouldn't affect most users)

Removed Features¶

HTTP sync server (deprecated, use branching instead)
JWT authentication (moved to enterprise edition)
Legacy sync protocol (incompatible with v2.3.x)

Known Issues¶

Beta Limitations¶

Vector Quantization: Some edge cases in high-dimensional spaces (>1024 dims)
Compression: FSST may not optimize for very short strings (<10 chars)
Branching: Cannot merge branches with schema conflicts
Time-Travel: Performance degrades with >1M historical versions

Test Failures (27 total)¶

5 vector quantization edge cases
8 advanced compression scenarios
6 sync protocol tests (feature disabled)
8 integration tests (being addressed)

Migration Guide¶

From v2.3.1¶

Update imports:

// Old
use heliosdb_lite::Database;

// New
use heliosdb_lite::EmbeddedDatabase;

Enable new features:

let config = Config::default()
    .with_vector_compression(true)
    .with_time_travel(true)
    .with_branching(true);

Update vector indices:

// Enable compression for existing indices
db.execute("ALTER INDEX vec_idx SET (compression = 'pq')")?;

Future Roadmap (v2.5.0)¶

Planned Features¶

Distributed consensus: Raft-based replication
Streaming aggregations: Real-time analytics
Graph traversals: Native graph operations
ML inference: Built-in model serving
Cloud native: S3/GCS storage backends

Performance Goals¶

1M+ vectors/sec insert rate
<100μs p99 latency for searches
20x compression for time-series data
Zero-overhead branching

Documentation¶

Updated Guides¶

Examples¶

Acknowledgments¶

This release represents months of intensive development and wouldn't have been possible without the dedication of our team and the valuable feedback from our community.

Special thanks to: - The DuckDB team for FSST/ALP compression algorithms - The Faiss team for product quantization insights - Our beta testers for invaluable feedback

Support¶

Resources¶

Documentation: https://heliosdb.dev/docs
GitHub Issues: https://github.com/heliosdb/heliosdb-lite/issues
Discord: https://discord.gg/heliosdb
Email: support@heliosdb.dev

License¶

HeliosDB-Lite is licensed under the MIT License.

HeliosDB-Lite v2.4.0-beta - Built for the future of embedded databases