---
title: "HeliosDB Nano Feature Index"
---

# HeliosDB Nano Feature Index

**Canonical feature × tutorial coverage map.** Every available feature has an entry here with a short description and a link to a hands-on tutorial or quick reference.

For the release history, see the [changelog](https://www.heliosdb.com/docs/nano/releases/changelog/).

---


The **Coverage** column rates how thoroughly each feature is documented:

- 5/5: long-form tutorial plus quick reference
- 4/5: tutorial, or several references with code examples
- 3/5: reference page with examples
- 2/5: brief mention in the release notes or README
- 1/5: mentioned only in the changelog

---

## SQL / DML / Query Execution

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Full SQL Core | JOINs, CTEs, subqueries, set ops, aggregates, CASE | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| Aggregate expressions | `SUM(a)+SUM(b)`, `CAST(AVG())`, CASE on COUNT | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| Window functions | Full SQL:2003 frame spec | 3/5 | [WINDOW_FUNCTIONS_QUICKREF](https://www.heliosdb.com/docs/nano/guides/quickstart/window_functions_quickref/) |
| Common table expressions | WITH RECURSIVE depth control | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| Subqueries | Scalar, derived, IN/EXISTS | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| String concatenation `\|\|` | NULL propagation, auto-cast | 2/5 | CHANGELOG |
| EXTRACT / date functions | EPOCH, YEAR, MONTH, etc. | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |
| INSERT … SELECT | FK/trigger/RLS-aware bulk insert | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| ON CONFLICT (Upsert) | DO UPDATE SET … EXCLUDED + MySQL ON DUPLICATE KEY | 3/5 | [UPSERT_QUICKREF](https://www.heliosdb.com/docs/nano/guides/quickstart/upsert_quickref/) |
| Parameterized LIMIT/OFFSET | `LIMIT $1 OFFSET $2` with type coercion | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |
| Keyset pagination | Constant-time deep pagination (~30 µs) | 5/5 | [KEYSET_PAGINATION_QUICKREF](https://www.heliosdb.com/docs/nano/guides/quickstart/keyset_pagination_quickref/), [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3120/) |
| Top-K sort optimization | LIMIT-driven early termination, O(N log k) | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3120/) |
| Generate_series / unnest | Table-valued functions | 2/5 | CHANGELOG |
| EXPLAIN / cost planner | JSON/XML/YAML output, ANALYZE | 4/5 | [EXPLAIN_AND_OPTIMIZATION](https://www.heliosdb.com/docs/nano/guides/tutorials/explain_and_optimization_tutorial/) |
| Implicit comma-joins | `FROM t1, t2 WHERE …` (WordPress compat) | 2/5 | CHANGELOG |
| Recursive CTEs | Depth-limited graph traversal in SQL | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| `gen_random_uuid` / `uuid_generate_v4` | UUID generation | 2/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |

## DDL / Schema

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| CREATE TABLE | All constraints + DEFAULT expressions + CHECK | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| PRIMARY KEY (inline + table) | Both syntaxes | 3/5 | [primary-keys](https://www.heliosdb.com/docs/nano/features/primary-keys/) |
| Foreign keys | CASCADE, SET NULL, RESTRICT | 4/5 | [foreign-keys](https://www.heliosdb.com/docs/nano/features/foreign-keys/) |
| UNIQUE constraints | Per-column + multi-column; ON CONFLICT detection | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| CHECK constraints | Expression-based row validation | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| GENERATED ALWAYS AS IDENTITY | SQL:2016 identity columns | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |
| SERIAL / BIGSERIAL / AUTO_INCREMENT | PG + MySQL alias | 3/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| DEFAULT expressions | `DEFAULT now()`, `DEFAULT CURRENT_USER` | 3/5 | CHANGELOG |
| ALTER TABLE | Multiple ops in single stmt | 3/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| CREATE INDEX | B-tree, ART, HNSW, GIN | 4/5 | [vector-search](https://www.heliosdb.com/docs/nano/features/vector-search/), [STORAGE_FILTERING](https://www.heliosdb.com/docs/nano/features/storage_filtering/) |
| CREATE SEQUENCE / nextval | Process-scoped sequence store | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |
| CREATE EXTENSION hdb_code | Code-graph bootstrap (opt-in) | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| CREATE SEMANTIC HASH INDEX | Merkle-tree subtree invalidation | 3/5 | [SEMANTIC_HASH_INDEX_QUICKREF](https://www.heliosdb.com/docs/nano/guides/quickstart/semantic_hash_index_quickref/) |
| TRUNCATE | Fast clear with ART purge | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| Per-column storage modes | Dictionary / Content-Addressed / Columnar | 4/5 | [per-column-storage](https://www.heliosdb.com/docs/nano/features/per-column-storage/) |

## Indexing & Search

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Adaptive Radix Tree (ART) | Zero-copy PK lookups, O(k) | 3/5 | [PRODUCT_QUANTIZATION_IMPLEMENTATION](https://www.heliosdb.com/docs/nano/features/product_quantization_implementation/) |
| HNSW vector search | Native k-NN, about 16x (internal tests, Nano 3.32.1 vs unquantized HNSW, see [benchmarks](https://www.heliosdb.com/benchmarks.html)) PQ | 5/5 | [VECTOR_SEARCH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/vector_search_tutorial/) |
| BM25 full-text search | tsvector / tsquery / @@ / ts_rank_cd | 4/5 | [FULL_TEXT_SEARCH](https://www.heliosdb.com/docs/nano/guides/tutorials/full_text_search_tutorial/) |
| Hybrid search | BM25 + vector via RRF/MMR | 4/5 | [FULL_TEXT_SEARCH](https://www.heliosdb.com/docs/nano/guides/tutorials/full_text_search_tutorial/) |
| GIN indexes (FTS) | ORM/migration compat (no-op currently) | 2/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3130/) |
| SIMD predicate pushdown | Storage-level filtering via bloom/zone-map/SIMD | 3/5 | [STORAGE_FILTERING](https://www.heliosdb.com/docs/nano/features/storage_filtering/) |
| Centrality-biased HNSW | Post-rerank with centrality weighting | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |
| UUID literal coercion | PK lookup with UUID columns | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3191/) |

## Transactions / Concurrency / MVCC

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| ACID transactions | Snapshot isolation, all-or-nothing | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| Explicit transactions | BEGIN / COMMIT / ROLLBACK | 3/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| Savepoints | Nested rollback boundaries | 3/5 | [SQL_FEATURES](https://www.heliosdb.com/docs/nano/features/sql_features/) |
| MVCC | Snapshot iso, read-your-writes | 4/5 | [../architecture/multi_user_transactions.md](https://www.heliosdb.com/docs/nano/architecture/multi_user_transactions/) |
| Optimistic conflict detection (`sync-experimental` build) | Vector clocks, field-level merge | 2/5 | CHANGELOG |

## Time-Travel / Branching

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Git-like branches | COW isolation for dev/test/A-B | 5/5 | [branching and time-travel tutorial](https://www.heliosdb.com/docs/nano/guides/branching_time_travel_tutorial/), [branching](https://www.heliosdb.com/docs/nano/features/branching/) |
| Selective branch sync | Replicate specific branches to remotes | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |
| AS OF TIMESTAMP | Query historical snapshots | 5/5 | [time-travel](https://www.heliosdb.com/docs/nano/features/time-travel/), [branching and time-travel tutorial](https://www.heliosdb.com/docs/nano/guides/branching_time_travel_tutorial/) |
| AS OF TRANSACTION | Query by txn ID | 4/5 | [time-travel](https://www.heliosdb.com/docs/nano/features/time-travel/) |
| MERGE BRANCH / DROP BRANCH | Branch lifecycle | 4/5 | [branching](https://www.heliosdb.com/docs/nano/features/branching/) |
| ON BRANCH override | Per-call branch redirect (MCP/LSP) | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |

## Encryption / Security / Compliance

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| AES-256-GCM TDE | Database-level transparent encryption | 5/5 | [ENCRYPTION_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/encryption_tutorial/), [ENCRYPTION](https://www.heliosdb.com/docs/nano/features/encryption/) |
| FIPS 140-3 (feature flag) | AWS-LC FIPS provider, Cert #4816 | 4/5 | [FIPS_COMPLIANCE_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/fips_compliance_tutorial/) |
| SCRAM-SHA-256 auth | PG-standard password hashing | 3/5 | [SCRAM_SHA256_AUTHENTICATION](https://www.heliosdb.com/docs/nano/features/scram_sha256_authentication/) |
| TLS / SSL | Encrypted wire (PG + MySQL) | 3/5 | [POSTGRESQL_SSL_QUICK_REFERENCE](https://www.heliosdb.com/docs/nano/guides/quickstart/postgresql_ssl_quick_reference/) |
| Row-Level Security (RLS) | Per-tenant isolation via policies (embedded API and REPL; SQL `CREATE POLICY` and wire/REST enforcement planned) | 4/5 | [RLS_POLICY_MANAGEMENT_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/rls_policy_management_tutorial/), [rls](https://www.heliosdb.com/docs/nano/features/rls/) |
| JWT sessions | Stateless auth | 3/5 | [JWT_AUTH_QUICK_REFERENCE](https://www.heliosdb.com/docs/nano/guides/quickstart/jwt_auth_quick_reference/) |
| OAuth2 (Google/GitHub) | PKCE, auto user creation | 4/5 | [AUTH_AND_OAUTH](https://www.heliosdb.com/docs/nano/guides/tutorials/auth_and_oauth_tutorial/) |
| Audit logging | Tamper-proof SHA-256 chain | 5/5 | [AUDIT_LOGGING_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/audit_logging_tutorial/), [AUDIT_LOGGING](https://www.heliosdb.com/docs/nano/features/audit_logging/) |
| Argon2id KDF | Memory-hard password hashing | 3/5 | [ENCRYPTION_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/encryption_tutorial/) |

## Stored Procedures / Triggers / Functions

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| PL/pgSQL functions and procedures | SQL statements, SELECT INTO, RETURN; control flow (IF / LOOP / WHILE / FOR / RAISE) planned | 3/5 | [procedural-language](https://www.heliosdb.com/docs/nano/features/procedural-language/) |
| Triggers | Accepted; bodies run only for BEFORE-row `NEW.col = expr` assignments (full trigger bodies planned) | 4/5 | [triggers](https://www.heliosdb.com/docs/nano/features/triggers/), [TRIGGER_EXECUTION_QUICK_REFERENCE](https://www.heliosdb.com/docs/nano/features/trigger_execution_quick_reference/) |
| Scalar functions | 100+ built-in | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| Aggregate functions | COUNT, SUM, AVG, MIN, MAX, STDDEV | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| User-defined functions | Composite types via JSON | 3/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |

## JSON / JSONB

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| JSONB type | Schemaless docs | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| JSONB operators | `->`, `->>`, `@>`, `?`, `#-` | 4/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| JSON path queries | Nested navigation | 3/5 | [SQL_REFERENCE](https://www.heliosdb.com/docs/nano/user-guide/sql-reference/) |
| json_agg | JSON array aggregation | 3/5 | CHANGELOG |

## Backend-as-a-Service (BaaS)

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| REST API (PostgREST-style) | `eq`, `neq`, `gt`, `gte`, `lt`, `lte`, `like`, `ilike`, `is`, `in` plus `not.` on `/rest/v1/{table}` (the table routes are a known issue in the current release; more operators planned) | 5/5 | [BAAS_REST_API_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/baas_rest_api_tutorial/) |
| Auth signup/token | `/auth/v1/signup`, `/auth/v1/token` | 4/5 | [AUTH_AND_OAUTH](https://www.heliosdb.com/docs/nano/guides/tutorials/auth_and_oauth_tutorial/) |
| OAuth2 Google/GitHub | PKCE flow | 4/5 | [AUTH_AND_OAUTH](https://www.heliosdb.com/docs/nano/guides/tutorials/auth_and_oauth_tutorial/) |
| RLS on REST (planned) | JWT-based row-level security for REST requests | 3/5 | [BAAS_REST_API_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/baas_rest_api_tutorial/) |
| Realtime WebSocket | Phoenix-protocol channels. Known issue: realtime events are not delivered in the current release; tracked by the Nano team | 5/5 | [REALTIME_WEBSOCKET](https://www.heliosdb.com/docs/nano/guides/tutorials/realtime_websocket_tutorial/) |
| ChangeNotifier | Event broadcast for REST table writes | 2/5 | CHANGELOG |
| Swagger UI | Auto-generated `/docs` | 3/5 | [SWAGGER_UI_QUICKSTART](https://www.heliosdb.com/docs/nano/guides/quickstart/swagger_ui_quickstart/) |

## Protocol Compatibility

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| PostgreSQL Wire v3 | psql, libpq, psycopg2, pg, JDBC | 5/5 | [POSTGRESQL_WIRE_PROTOCOL](https://www.heliosdb.com/docs/nano/features/postgresql_wire_protocol/) |
| PG Extended Query | Parse / Bind / Execute / Describe | 3/5 | [PARAMETERIZED_QUERIES](https://www.heliosdb.com/docs/nano/guides/parameterized_queries/) |
| MySQL Wire v10 | mysql, JDBC, mysql2, mysqli, WordPress | 5/5 | [MYSQL_WIRE](https://www.heliosdb.com/docs/nano/guides/tutorials/mysql_wire_tutorial/) |
| MySQL Prepared Stmts | `$N` substitution, COM_STMT_PREPARE | 3/5 | [MYSQL_WIRE](https://www.heliosdb.com/docs/nano/guides/tutorials/mysql_wire_tutorial/) |
| Unix Domain Sockets | Zero-TCP for same-host | 4/5 | [UNIX_SOCKETS_QUICKSTART](https://www.heliosdb.com/docs/nano/guides/quickstart/unix_sockets_quickstart/) |
| Flush message (`H`) | Pipelined queries | 2/5 | CHANGELOG |
| Multi-statement queries | `;`-separated stmts | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |
| MySQL SHOW commands | SHOW TABLES/COLUMNS/INDEX | 3/5 | CHANGELOG |
| MySQL date/time functions | DATE_FORMAT, DATE_ADD, UNIX_TIMESTAMP | 3/5 | CHANGELOG |
| MySQL identifier quoting | Backtick / double-quote / case-folding | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |
| `heliosdb_capability_report()` | Migration tool discovery | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3140/) |

## Materialized Views

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| MV creation | Persistent query results | 5/5 | [MATERIALIZED_VIEWS_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/materialized_views_tutorial/) |
| Refresh MV | Full recompute | 4/5 | [materialized-views](https://www.heliosdb.com/docs/nano/features/materialized-views/) |
| Incremental MV | Delta computation | 4/5 | [INCREMENTAL_MATERIALIZED_VIEWS](https://www.heliosdb.com/docs/nano/features/incremental_materialized_views/) |
| Concurrent MV refresh | Multi-MV in parallel | 3/5 | [CONCURRENT_MV_REFRESH_QUICK_REF](https://www.heliosdb.com/docs/nano/guides/concurrent_mv_refresh_quick_ref/) |
| MV scheduler | CPU-aware auto refresh | 3/5 | [MATERIALIZED_VIEWS_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/materialized_views_tutorial/) |
| MV dependency tracking | Cascading invalidation | 3/5 | [INCREMENTAL_MATERIALIZED_VIEWS](https://www.heliosdb.com/docs/nano/features/incremental_materialized_views/) |

## Code-Graph (opt-in `--features code-graph`)

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Code-graph bootstrap | Tree-sitter AST for 8 languages | 4/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| Symbol extraction | Functions, classes, methods, types | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| Reference resolution | Cross-file linking (exact/heuristic) | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3160/) |
| `lsp_definition` | "Where is X defined?" | 4/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| `lsp_references` | "Who uses X?" | 4/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| `lsp_call_hierarchy` | BFS over CALLS edges | 4/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| `lsp_hover` | Signature lookup | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| `lsp_document_symbols` | File outline | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |
| `lsp_rename_preview/apply` | Identifier-boundary write-back | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |
| Symbol embeddings | `body_vec VECTOR(n)` lazy column | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| Pluggable embedders | NoopEmbedder + HttpEmbedder | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| `code-embed` feature | fastembed-rs (BGESmallENV15, 384-dim) | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| Runtime grammar registry | Dynamic grammar loading | 2/5 | CHANGELOG |
| Pluggable extractors | Per-language runtime registration | 2/5 | CHANGELOG |
| Semantic Hash Index | Merkle-tree subtree invalidation | 3/5 | [SEMANTIC_HASH_INDEX_QUICKREF](https://www.heliosdb.com/docs/nano/guides/quickstart/semantic_hash_index_quickref/) |
| `_hdb_code_languages` view | List static + runtime grammars | 2/5 | CHANGELOG |

## Graph-RAG (opt-in `--features graph-rag`)

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Universal node/edge schema | `_hdb_graph_nodes` & `_hdb_graph_edges` plain tables | 4/5 | [GRAPH_RAG_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/graph_rag_tutorial/) |
| Symbol projection | `graph_rag_project_symbols()` | 3/5 | [GRAPH_RAG_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/graph_rag_tutorial/) |
| BFS graph search | Seed → expand → subgraph | 4/5 | [GRAPH_RAG_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/graph_rag_tutorial/) |
| Centrality weighting | Post-rerank scoring bias | 3/5 | [GRAPH_RAG_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/graph_rag_tutorial/) |
| Vector entity linker | Cross-modal MENTIONS via cosine | 3/5 | [GRAPH_RAG_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/graph_rag_tutorial/) |
| Docling PDF/Office ingestion | `graph_rag_ingest_*` | 4/5 | [DOCLING_INGESTION](https://www.heliosdb.com/docs/nano/guides/tutorials/docling_ingestion_tutorial/) |
| Graph traversal tools | `heliosdb_graph_traverse / _path / _add_edge` | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3110/) |

## MCP Endpoint (opt-in `--features mcp-endpoint`)

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| MCP JSON-RPC dispatcher | Native server for Claude Code/Cursor/Aider | 5/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| 16-tool catalogue | 10 DB-backed + 6 RAG | 4/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| MCP resource URIs | `heliosdb://schema/{table}` etc. | 3/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| WebSocket transport | Real-time tool calls | 3/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| Stdio transport | Library only (no engine subcommand); for stdio MCP use the HeliosDB CodeKB MCP binary | 3/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| SSE transport | Server-sent events | 3/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| Progress notifications | Streaming `notifications/progress` | 3/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |
| HTTP POST + SSE pairing | Forward progress to SSE | 2/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |
| Verbose tool discovery | `tools/list?verbose=true` + `helios/info` | 3/5 | [MCP_ENDPOINT](https://www.heliosdb.com/docs/nano/guides/tutorials/mcp_endpoint_tutorial/) |

## Persistence / WAL / Replication

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| RocksDB LSM storage | Write-optimised KV store | 3/5 | ../architecture |
| Write-ahead log | Durability guarantee | 3/5 | [WAL_QUICK_REFERENCE](https://www.heliosdb.com/docs/nano/guides/quickstart/wal_quick_reference/) |
| WAL streaming replication (default build) | Warm standby, async repl | 4/5 | [HA_HANDS_ON_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/ha_hands_on_tutorial/) |
| Branch-based replication (`ha-tier2/branch-replication` build) | Selective branch sync | 3/5 | [release notes](https://www.heliosdb.com/docs/nano/releases/release_notes_v3190/) |
| Multi-primary active-active (`ha-tier2` build) | Vector-clock conflict resolution | 3/5 | [high-availability](https://www.heliosdb.com/docs/nano/features/high-availability/) |
| Sharding (`ha-tier3` build) | Consistent hash ring | 3/5 | [high-availability](https://www.heliosdb.com/docs/nano/features/high-availability/) |
| Content-addressed dedup (`ha-dedup` build) | Cross-node BLAKE3 dedup | 3/5 | [high-availability](https://www.heliosdb.com/docs/nano/features/high-availability/) |
| In-memory mode | `--memory` for tests/CI | 3/5 | [IN_MEMORY_MODE_QUICKREF](https://www.heliosdb.com/docs/nano/guides/quickstart/in_memory_mode_quickref/) |

## Backup / Restore / Dump

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Database dump | zstd / gzip / brotli / lz4 | 4/5 | [BACKUP_RESTORE](https://www.heliosdb.com/docs/nano/guides/tutorials/backup_restore_tutorial/) |
| Selective export | Per-table/schema | 3/5 | [BACKUP_RESTORE](https://www.heliosdb.com/docs/nano/guides/tutorials/backup_restore_tutorial/) |
| Import/export formats | CSV, JSON, JSONL, Parquet, Arrow, SQL | 3/5 | [BACKUP_RESTORE](https://www.heliosdb.com/docs/nano/guides/tutorials/backup_restore_tutorial/) |
| SQLite import | One-shot `.sqlite` conversion | 3/5 | features/sqlite/ |

## Observability

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| Tracing / structured logging | `tracing` macros | 3/5 | [TRACING_GUIDE](https://www.heliosdb.com/docs/nano/user-guide/performance-tracing/) |
| EXPLAIN ANALYZE | Cost-based plans, JSON/XML/YAML | 4/5 | [EXPLAIN_AND_OPTIMIZATION](https://www.heliosdb.com/docs/nano/guides/tutorials/explain_and_optimization_tutorial/) |
| CPU monitoring (sysinfo) | MV scheduler awareness | 2/5 | CHANGELOG |
| Result cache | 128-entry LRU + dml/ddl invalidation | 3/5 | CHANGELOG |
| Audit log | Tamper-proof SHA-256 | 5/5 | [AUDIT_LOGGING_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/audit_logging_tutorial/) |

## Embedded Rust API

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| In-process database | Zero-network, no daemon | 4/5 | [API_REFERENCE](https://www.heliosdb.com/docs/nano/api/rest-api/), [docs.rs](https://docs.rs/heliosdb-nano) |
| Async runtime (Tokio) | Non-blocking I/O | 3/5 | [API_REFERENCE](https://www.heliosdb.com/docs/nano/api/rest-api/) |
| Code indexing API | `code_index(opts)` idempotent | 3/5 | [CODE_GRAPH_TUTORIAL](https://www.heliosdb.com/docs/nano/guides/tutorials/code_graph_tutorial/) |
| Branch operations | `create/switch/list/merge` | 3/5 | [API_REFERENCE](https://www.heliosdb.com/docs/nano/api/rest-api/) |
| Transaction control | `begin/commit/rollback/savepoint` | 3/5 | [API_REFERENCE](https://www.heliosdb.com/docs/nano/api/rest-api/) |

## SDKs & Bindings

| Language | UVP | Doc |
|----------|-----|-----|
| Rust (`heliosdb-nano`) | Embedded API | [docs.rs](https://docs.rs/heliosdb-nano) |
| Python (`@heliosdb/client`-equiv) | psycopg2 + REST + Realtime | [api/python-sdk.md](https://www.heliosdb.com/docs/nano/api/python-sdk/), [PYTHON_VECTOR_APP](https://www.heliosdb.com/docs/nano/guides/tutorials/sdk/python_vector_app/) |
| TypeScript (`@heliosdb/client`) | REST + Realtime + Auth fluent API | [api/typescript-sdk.md](https://www.heliosdb.com/docs/nano/api/typescript-sdk/), [NODEJS_BAAS_APP](https://www.heliosdb.com/docs/nano/guides/tutorials/sdk/nodejs_baas_app/) |
| Go | pgx-style + REST | [api/go-sdk.md](https://www.heliosdb.com/docs/nano/api/go-sdk/), [GO_EMBEDDED_APP](https://www.heliosdb.com/docs/nano/guides/tutorials/sdk/go_embedded_app/) |
| ORMs (any) | SQLAlchemy / Django / Prisma / Drizzle / TypeORM / Sequelize / Hibernate / GORM / SeaORM / Diesel | [ORM_SUPPORT](https://www.heliosdb.com/docs/nano/features/orm_support/), [DRIZZLE_PRISMA_COMPAT](https://www.heliosdb.com/docs/nano/guides/tutorials/drizzle_prisma_compat/) |

## Tooling / CLI

| Feature | Summary | Coverage | Doc |
|---------|---------|----------|-----|
| `heliosdb-nano` binary | ~32 MB single executable | 4/5 | [README](https://www.heliosdb.com/docs/nano/readme/) |
| REPL | Zero-setup interactive SQL | 4/5 | [REPL_COMMAND_REFERENCE](https://www.heliosdb.com/docs/nano/guides/user/repl_command_reference/) |
| Release binaries / crates.io / container image | GitHub Releases binaries, `cargo install heliosdb-nano`, `ghcr.io/heliosdatabase/heliosdb-nano` | 4/5 | [README](https://www.heliosdb.com/docs/nano/readme/) |