---
title: "HeliosDB Nano v3.19 — From Embedded SQL to AI-Native Retrieval Engine"
description: "Five weeks, eight minor versions, three new tracks. Code-Graph (CREATE EXTENSION hdb_code), Graph-RAG (WITH CONTEXT clause), native MCP server. In-process fastembed, Docling ingestion, Drizzle/Prisma/TypeORM compat."
date: 2026-04-20
updated: 2026-04-20
tag: "Release"
canonical: https://www.heliosdb.com/blog/nano-3-19-ai-native-retrieval-engine.html
---

# HeliosDB Nano v3.19 — From Embedded SQL to AI-Native Retrieval Engine

HeliosDB Nano went from v3.11 to v3.19.1 in five weeks. The version number is a footnote; the shape of the product changed. Nano was an embedded SQL+vector database with PostgreSQL/MySQL wire compatibility and 32 MB on disk. It is now an AI-native retrieval engine: SQL + Vector + Graph + Code-Graph + Graph-RAG + native MCP server + an in-process embedder, in a 32 MB all-features release binary, with zero external services required.

This post is the headline. The four follow-ups go deep on the individual tracks — [Code-Graph](https://www.heliosdb.com/blog/code-graph-sql-callable-lsp.html), [Graph-RAG](https://www.heliosdb.com/blog/graph-rag-with-context-clause.html), [native MCP server](https://www.heliosdb.com/blog/native-mcp-server-database-tool-provider.html), plus the [HeliosProxy v0.4 release](https://www.heliosdb.com/blog/heliosproxy-0-4-programmable-data-plane.html) for the platform side.

## Three Tracks That Reframe Nano

### Track 1 — Code-Graph (v3.15 → v3.18)

`CREATE EXTENSION hdb_code; CREATE AST INDEX ON src/` turns your codebase into a queryable AST. The full LSP surface is exposed as SQL table functions: `lsp_definition`, `lsp_references`, `lsp_call_hierarchy`, `lsp_hover`, plus diff helpers (`helios_lsp_references_diff`, `helios_lsp_body_diff`, `helios_ast_diff`) and the v3.19 write-side `helios_lsp_rename_preview` / `helios_lsp_rename_apply` with sha256 conflict checking.

Eight languages out of the box (Rust, Python, TypeScript, TSX, JavaScript, Go, Markdown, SQL), plus a runtime grammar registry that lets you plug in any tree-sitter grammar at runtime via `register_grammar` + `register_extractor`. Every `lsp_*` call accepts `ON BRANCH '<name>'` per-call override and `AS OF` in either order — code intelligence is time-travel-aware on the same query.

### Track 2 — Graph-RAG (v3.17 → v3.19)

RAG pipelines glue a vector store, a graph DB, an entity linker, and a re-ranker. Nano collapses them. `WITH CONTEXT` is a SQL clause; `_hdb_graph.nodes` and `_hdb_graph.edges` are queryable tables; entity linking and auto-projection happen on insert. v3.19 added six ingestion adapters — `graph_rag_ingest_docs` / `_email` / `_issues` / `_qa` plus Docling-backed `_pdf` / `_office` / `_audio` / `_image`. Centrality-biased re-ranking, semantic-Merkle invalidation via `CREATE SEMANTIC HASH INDEX`, and a vector-similar entity linker (`graph_rag_link_vector`) round it out.

### Track 3 — Native MCP Server (v3.18 → v3.19)

Every modern coding agent — Claude Code, Cursor, Continue, Codex, Aider — speaks Model Context Protocol. Nano speaks it natively on three transports: `POST /mcp` (HTTP JSON-RPC), `/mcp/ws` (WebSocket), `/mcp/sse` (SSE). Plus stdio for sandboxed agents. JWT auth, Unix-socket transport, public-bind hardening (opt-in only). v3.19 added streaming `notifications/progress` events, single-shot `helios/info` discovery, `tools/list?verbose=true`, and HTTP POST + SSE session pairing.

## The v3.19 Backlog Sweep

v3.19.0 (April 25) closed the residual FR backlog the v3.18 review left open. The most important deltas for users:

- **`code-embed` feature** — fastembed-rs in-process with BGESmallENV15 (384-dim, ~30 MB model cache, no on-disk impact on the binary). Compile with `--features code-embed` and Nano embeds locally. `HttpEmbedder` remains available for managed embedding services.
- **Docling content-conversion ingestion** — PDFs, Office docs, audio (transcribed), and images (OCR'd) project into `_hdb_graph.nodes` with `CONTAINS` edges. Idempotent via source-ref keys.
- **`helios_lsp_rename_apply`** — write-back rename refactor, identifier-boundary aware, sha256 conflict check, optional `dry_run`.
- **Streaming MCP progress** — `helios_graphrag_search` emits "seeding" and "*n* hits" events when the client opts in via `_meta.progressToken`.
- **Scope-chain resolver via `IMPORTS`** — unresolved `CALLS` / `REFERENCES` upgrade to `Exact` when an unambiguous `IMPORTS` edge in the same file ends in the bare name.
- **`hdb_code_languages` system view** — queryable list of supported + runtime-registered grammars.
- **Centrality-biased + prefilter-aware HNSW wrapper** — over-fetches `k × over_fetch_multiplier` candidates, applies row-level prefilter, re-scores with `(1−α)·distance − α·centrality`.

## Defensible Numbers

v3.19 also landed acceptance benchmarks — first measured numbers we are willing to put on the website:

| Workload | Target | Measured |
| --- | --- | --- |
| `WITH CONTEXT` mean (10k-node fixture, 100 queries) | ≤ 500 ms | **62 ms** |
| Entity linker precision (hand-labelled fixture) | ≥ 80 % | **100 %** |
| All-features release binary size | — | **35.0 MiB** |

Source: `tests/with_context_bench.rs`, `tests/linker_precision.rs`, `docs/followups/build-report.md`. Single-machine, release build, criterion methodology.

## v3.19.1 — the One-Day-After Fix

v3.19.1 (April 25, hours after v3.19.0) ships a single targeted fix: UUID literal coercion at PK index lookup. `SELECT … WHERE id = '<uuid>'` against a UUID-typed PK previously emitted `Value::String` regardless of the column's declared type, and the ART point-lookup encoded the search key by Value variant — so the lookup missed every row. Three patches land the fix at `try_index_point_lookup`, the `fast_parse_one_value` fast path, and the SIMD post-walk filter. CloudV2's admin DB — the bug's reporter — can now graduate `cloud-v2.heliosdb.com` to production.

## Drizzle / Prisma / TypeORM Compatibility (v3.14.x)

Earlier in this release window we closed B1–B36, the full set of bugs Drizzle / Prisma / TypeORM exposed in our extended-protocol implementation. Highlights: `DEFAULT` in `VALUES`, extended-Q `RETURNING`, parameterised `LIMIT` / `OFFSET`, `UPDATE SET` coercion, mixed-qualifier `GROUP BY`, `DATE` key comparison, FK validation with quoted identifiers, and the fast-path-bypass-was-a-data-integrity-hole fix in v3.14.10. Every modern Node ORM works against Nano now without workarounds.

## Compatibility

All of the above is additive. Code-graph, graph-RAG, MCP-endpoint, and code-embed are Cargo-feature-gated; embedded-only callers compile without them. The default release binary stays small. The PostgreSQL / MySQL wire surface is unchanged. SQL behaviour is unchanged except where v3.14.x bug fixes corrected divergence from PostgreSQL semantics.

## Where This Goes Next

Read the deep-dives:

- [**Code-Graph: SQL-Callable LSP Inside Your Database**](https://www.heliosdb.com/blog/code-graph-sql-callable-lsp.html)
- [**Graph-RAG: The `WITH CONTEXT` Clause and Why RAG Belongs in SQL**](https://www.heliosdb.com/blog/graph-rag-with-context-clause.html)
- [**Native MCP Server: Why Your Database Should Be an MCP Tool Provider**](https://www.heliosdb.com/blog/native-mcp-server-database-tool-provider.html)

HeliosDB Nano is open source under Apache 2.0. The repo is [github.com/dimensigon/HDB-HeliosDB-Nano](https://github.com/dimensigon/HDB-HeliosDB-Nano); full CHANGELOG lives there.