nopaldb 0.4.31

Graph database with MVCC and NQL query language

NopalDB 🌵

High-performance embedded graph database for Python, written in Rust: ACID transactions, MVCC time-travel, a Cypher-like query language (NQL), vector search, and zero-copy Apache Arrow export for ML pipelines.

Runs in-process — no server to deploy. One pip install, one file on disk.

Install

pip install nopaldb

Prebuilt wheels for Linux (x86_64/aarch64), macOS (Intel/Apple Silicon) and Windows, for CPython 3.10+ (abi3: one wheel per platform covers all versions).

Quickstart

import nopaldb

graph = nopaldb.Graph.open("./data.db")

# ACID transactions
tx = graph.begin_transaction()
alice = tx.add_node("Person", {"name": "Alice", "age": 30})
bob = tx.add_node("Person", {"name": "Bob", "age": 25})
tx.add_edge(alice, bob, "KNOWS")
tx.commit()

# Query with NQL
result = graph.execute_nql("""
    find p.name, p.age
    from (p:Person)
    where p.age > 25
""")
for row in result:
    print(f"{row['p.name']}: {row['p.age']}")

graph.close()

Isolation levels

tx = graph.begin_transaction(isolation="serializable")
# read_committed (default) | repeatable_read | serializable | read_uncommitted

Serializable transactions detect write conflicts and deadlocks; see the durability guarantees and isolation guide.

Arrow / ML pipelines

import pyarrow as pa

arrow_bytes = graph.to_arrow(label="Person")
batch = pa.ipc.open_stream(arrow_bytes).read_next_batch()
df = batch.to_pandas()   # zero-copy into Pandas / Polars / PyTorch pipelines

Good to know

• One process per data directory (embedded file lock). Threads within the process run in parallel — the bindings release the GIL during database calls.
• Use graph.bulk_loader(batch_size) for large ingestions.
• Time-travel: MVCC version history is queryable; old versions are garbage collected on demand.

Links

• Repository & docs: https://github.com/sharop/nopaldb
• Adoption guide: https://github.com/sharop/nopaldb/blob/main/docs/ADOPTION.md
• NQL reference: https://github.com/sharop/nopaldb/blob/main/docs/en/NQL_REFERENCE.md
• Rust crate: https://crates.io/crates/nopaldb

License: AGPL-3.0-only. NopalDB™ is a trademark of Sergio Haro Pérez.