Skip to content
HeliosDB HeliosDB Full

HeliosDB Full v7.4.0 Release Notes

HeliosDB Full v7.4.0 Release Notes

Release Date: 2026-04-16 Theme: SQL surfaces for graph + hybrid search, plus a new MCP crate

Highlights

v7.4.0 brings new SQL-level access to capabilities that previously required Cypher or low-level vector APIs, and introduces the new heliosdb-mcp crate — HeliosDB Full’s first native Model Context Protocol server.

What’s New

Graph SQL Surface (NEW)

Existing graph engines in heliosdb-models/graph are now accessible from SQL:

SELECT * FROM graph_traverse(
  start_node => 'uuid-here',
  edge_label => 'KNOWS',
  direction  => 'OUT',
  depth      => 3
);


SELECT * FROM graph_shortest_path(
  from_node => 'uuid-a',
  to_node   => 'uuid-b',
  algorithm => 'astar',
  weight_col => 'distance'
);

Cypher and ISO GQL support continues unchanged for advanced graph queries.

Hybrid Search SQL Surface (NEW)

Existing capabilities in heliosdb-vector/fulltext and heliosdb-vector/hybrid-search now have a SQL surface:

SELECT * FROM hybrid_search(
  table_name   => 'documents',
  query_text   => 'distributed database research',
  query_vector => embed('distributed database research'),
  vector_column=> 'embedding',
  text_column  => 'content',
  fusion       => 'rrf',
  limit        => 50
);

RRF, MMR, and Linear fusion are now standardized across the workspace.

Compiled Plan Registry (NEW)

PREPARE COMPILED report_query AS
  SELECT customer_id, sum(amount) FROM transactions
  WHERE created_at >= $1 GROUP BY customer_id;


EXECUTE report_query('2026-01-01');

LRU-cached plans skip parsing/planning. Distinct from the existing distributed query optimizer — this is local plan caching for repeat single-node execution.

heliosdb-mcp Crate (NEW)

A new engine-agnostic crate brings native MCP (Model Context Protocol) support to Full. 29 tools total:

Inherited from Nano baseline (10):

  • heliosdb_query, heliosdb_schema, heliosdb_list_tables, heliosdb_create_table, heliosdb_insert
  • heliosdb_branch_create, heliosdb_branch_list, heliosdb_branch_merge
  • heliosdb_search, heliosdb_time_travel

New in v7.4.0 (Full-only):

  • heliosdb_cypher_query — Cypher queries via heliosdb-models/gql
  • heliosdb_nl2sql — natural-language-to-SQL via heliosdb-nl
  • heliosdb_lakehouse_query — query Iceberg/Delta tables
  • heliosdb_index_advisor — get autonomous index recommendations
  • heliosdb_hybrid_search / heliosdb_graph_traverse / heliosdb_graph_path
  • heliosdb_embed_and_store
  • …and more

The crate is engine-agnostic via the McpBackend trait, so it can serve any HeliosDB deployment.

Performance: Arena Allocation (Internal)

heliosdb-common::arena::RequestArena (bumpalo-based) is now available workspace-wide. The new heliosdb-query::local_executor uses it for transient row buffers in single-node execution paths. Distributed execution paths are unchanged.

Workspace Changes

  • 194 crates (was 193 — added heliosdb-mcp)
  • New dependencies: bumpalo, lru (in heliosdb-common and heliosdb-query)

Known Issues

  • torch-sys 0.17.0 build failure in heliosdb-research/quantum on hosts with PyTorch 2.8.0. Workaround: LIBTORCH_BYPASS_VERSION_CHECK=1. Pre-existing issue unrelated to v7.4.0 changes; tracked separately.

Migration

No breaking changes. v7.4.0 is fully wire-compatible with v7.3.x. Existing Cypher queries, distributed plans, and protocol adapters are unaffected.

To use the new heliosdb-mcp crate, add it to your deployment manifest:

[dependencies]
heliosdb-mcp = "7.4"

And implement the McpBackend trait wiring to your engine layer.