HeliosDB-Lite v3.6.0 Release Notes
Headline
v3.6.0 is the largest feature release in HeliosDB-Lite history, adding 22 previously internal-only features to the SQL interface, comprehensive database hardening, and a 129x query performance improvement via plan caching.
Performance
- Plan Cache: 129x average speedup on repeated queries (skip parse/plan/optimize)
- vs PostgreSQL 16: 33 of 35 benchmark categories won (up from 34/35 in v3.5)
- REFRESH MATVIEW: Flipped from PostgreSQL win (5.8x) to Helios win (1,279x)
New SQL Commands
| Command | Description |
|---|---|
BACKUP DATABASE [INCREMENTAL] [TO '<path>'] | COW incremental-forever backup |
RESTORE DATABASE FROM '<id>' [TO BRANCH '<name>'] | Restore with chain walking |
RECOVER DATABASE TO TIMESTAMP '<ts>' [AS BRANCH '<name>'] | Point-in-time recovery with branch forking |
VACUUM [FULL] [ANALYZE] [table] | MVCC version cleanup + statistics |
CHECKPOINT [FORCE] | WAL flush and rotation |
REINDEX TABLE/INDEX | Force index rebuild |
ALTER TABLE ENABLE/DISABLE ROW LEVEL SECURITY | RLS toggle |
CREATE/DROP POLICY | Row-level security policies |
CREATE ROLE WITH RATE_LIMIT <rpm> | Per-user rate limiting |
CREATE ROLE WITH SSL_REQUIRED | Connection-level SSL enforcement |
ALTER SYSTEM ROTATE ENCRYPTION KEY | Encryption key rotation |
ALTER TABLE ENABLE/DISABLE ZERO KNOWLEDGE ENCRYPTION | Per-table ZKE |
ALTER COLUMN SET COMPRESSION zstd/lz4/none | Per-column compression |
ALTER MATERIALIZED VIEW SET (refresh_interval='5m') | MV auto-refresh scheduling |
CREATE/DROP EXTENSION FROM '<path>' | WASM plugin management |
CREATE/DROP PUBLICATION/SUBSCRIPTION | Logical replication (feature-gated) |
CONSOLIDATE FILTER [table] | SMFI rebuild |
GRANT role TO user | Role hierarchy via custom parser |
New SQL Functions
| Function | Description |
|---|---|
pg_cancel_backend(pid) | Cancel a running query |
pg_terminate_backend(pid) | Terminate a session |
pg_backend_pid() | Get current process ID |
% (modulo operator) | Integer and float modulo |
New System Views (22 views added, 94 total)
| View | Category |
|---|---|
helios_dictionary | Lists all 94 system views (Oracle DICT equivalent) |
helios_audit_log | Tamper-proof audit trail |
helios_bloom_filters | Bloom filter statistics |
helios_zone_maps | Zone map min/max statistics |
helios_resource_usage | HTAP quota monitoring |
helios_index_stats | Index metadata |
helios_advisor_recommendations | Workload advisor output |
pg_stats | PG-compatible column statistics |
helios_dedup_stats | Content-addressed dedup ratios |
helios_prefetch_stats | Prefetch cache stats |
helios_smfi_status | Self-maintaining filter status |
helios_encryption_keys | Key rotation history |
helios_zke_status | ZKE per-table status |
helios_mv_refresh_status | MV auto-refresh schedule |
helios_column_compression | Per-column codec |
pg_publications | Logical replication publications |
pg_subscriptions | Logical replication subscriptions |
helios_extensions | WASM plugin registry |
helios_graphql_status | GraphQL gateway status |
helios_circuit_breaker_status | Circuit breaker config |
helios_backups | Backup metadata catalog |
helios_user_quotas | Rate limit quota tracking |
Security Hardening
- PBKDF2: 100,000 iterations (was 4,096)
- Resource limits: max_result_rows (1M), CTE depth (1000), subquery depth (64), expression depth (128), memory per query
- CRC32 checksums: Opt-in data integrity verification
- PRAGMA integrity_check: Full data corruption scan
- API validation: SQL size (1MB), param count (64K), timeout bounds
- PostgREST: Refactored to parameterized queries (SQL injection eliminated)
PL/pgSQL Enhancements
- FOR loops (numeric + query)
- WHILE loops
- CASE (searched + simple)
- Cursors (OPEN/FETCH/CLOSE)
- EXIT/CONTINUE
- SELECT INTO
- EXECUTE (dynamic SQL)
Optimizer
- More robust error handling in the optimizer
- CTE conflict in filtered scans resolved
Graph Adjacency Lists
Property graph layer with concurrent adjacency lists:
- Nodes: 64-bit ID with optional label and properties
- Edges: Directed, typed, optionally weighted
- Traversal: BFS, Dijkstra shortest path, A* with pluggable heuristic
- SQL functions:
graph_bfs(),graph_shortest_path(),graph_a_star(),graph_neighbors()(declared; wiring pending storage backend integration)
BM25 & Hybrid Search
RAG-native lexical and hybrid search:
- BM25 inverted index with Okapi parameters (k1=1.2, b=0.75)
- Unicode-aware tokenizer with ASCII folding
- Hybrid search: weighted linear combination or Reciprocal Rank Fusion (RRF)
- Rerankers: RRF (Cormack/Clarke 2009, k=60) and Maximal Marginal Relevance (MMR)
- Bloom filter skip: short-circuit term lookups for non-existent terms
Compiled Query Plans
- Normalized-SQL fingerprinting (comments stripped, literals replaced)
- Prepared plans with typed parameter slots
- Bounded LRU plan cache (512 entries)
Production Hardening
| Feature | Description |
|---|---|
| FK constraint enforcement | INSERT/UPDATE/DELETE validate foreign keys |
| MVCC GC background thread | 5-minute interval, 1-hour retention window |
| Backup snapshot consistency | Single-pass scan for consistent snapshots |
| Index error escalation | PK/UNIQUE violations return ERROR, not warning |
| NaN/Infinity guards | Aggregate functions reject NaN/Infinity |
| SQL cursors | DECLARE/FETCH/CLOSE for streaming result sets |
| Connection management | Timeouts, idle disconnect, rollback on disconnect |
| DDL locking | Schema operations are serialized |
| /metrics endpoint | Prometheus-compatible metrics |
| /health endpoint | Health check (HTTP 200 + JSON) |
| SET TRANSACTION ISOLATION LEVEL | Runtime isolation level control |
Breaking Changes
None. All changes are additive.