NopalDB

High-performance embedded graph database with ACID transactions, MVCC time-travel, a built-in query language (NQL), and Apache Arrow analytics.

Features

ACID + MVCC — snapshot isolation and time-travel queries over a versioned store.
NQL — a Cypher-like query language for pattern matching and traversal.
Embedded — runs in-process, no separate server. Sled-backed storage by default.
Analytics — zero-copy export to Apache Arrow / Parquet (analytics feature).
Optional tiers — vector embeddings + HNSW, full-text search, graph algorithms, ML tensors, OWL reasoning and SHACL validation, all behind feature flags.

Install

cargo add nopaldb

Requires Rust ≥ 1.85 (edition 2024).

Quickstart

use nopaldb::{Edge, Graph, Node, PropertyValue, Result};

#[tokio::main]
async fn main() -> Result<()> {
    // Open (or create) an embedded graph at a path
    let graph = Graph::open("my_graph.db").await?;

    // Add nodes with properties
    let alice = graph
        .add_node(Node::new("Person").with_property("name", PropertyValue::String("Alice".into())))
        .await?;
    let bob = graph
        .add_node(Node::new("Person").with_property("name", PropertyValue::String("Bob".into())))
        .await?;

    // Connect them with an edge
    graph.add_edge(Edge::new(alice, bob, "KNOWS")).await?;

    Ok(())
}

Feature flags

Feature	Enables
`storage-sled` (default)	Sled-backed embedded storage
`analytics`	Apache Arrow / Parquet export
`ml`	ML tensors (implies `analytics`)
`algorithms`	Graph algorithms (community detection, centrality, …)
`embeddings`, `embeddings-index`	Vector embeddings + HNSW ANN index
`fulltext`	Full-text search (Tantivy)
`reasoner`, `owl-import`, `shacl`	OWL EL reasoning, RDF/OWL import, SHACL validation
`python`	PyO3 bindings (used to build the Python package)

Convenience meta-features: core, semantic, full. See Cargo.toml for the full list.

Python

NopalDB also ships as a Python package built with maturin. See the repository for build instructions.

License

The nopaldb library (this crate and its Python bindings) is licensed under the Mozilla Public License 2.0 (MPL-2.0) — file-level copyleft, so it can be embedded in projects of any license while changes to NopalDB's own files stay open. The companion applications nopaldb-mcp and ndbstudio are AGPL-3.0-only. Releases ≤ 0.4.31 were AGPL-3.0-only.