Files
lancedb/python
lancedb-gatefixer[bot] ec80acb668 fix(python): expose inline types to downstream checkers (#3817)
## Summary

- publish the PEP 561 `py.typed` marker so downstream type checkers
consume the inline public annotations
- add a Pyright contract test that distinguishes synchronous `connect`
from awaited `connect_async`
- verify the marker is present in the installed package

## Root cause

The public Python module already annotated `lancedb.connect` as
synchronous and `lancedb.connect_async` as asynchronous. The private
native `_lancedb.connect` stub is intentionally awaitable because it
backs `connect_async`. However, the distribution did not include a PEP
561 marker, so downstream tools such as mypy could ignore the public
inline annotations and expose misleading or incomplete type information.

## Validation

- `python/.venv/bin/ruff format --check python/python/tests/test_db.py
python/python/type_tests/connect.py`
- `python/.venv/bin/ruff check .`
- `cd python && .venv/bin/pytest
python/tests/test_db.py::test_package_includes_pep_561_marker -q`
- `cd python && .venv/bin/pyright --pythonpath .venv/bin/python`
- downstream mypy contract check for both public connection functions

Fixes #2159

<!-- lance-gatekeeper-fix:v1 agent=b07901451487187fc03f61890d3aa6bb
generation=1 -->

Co-authored-by: lancedb-gatefixer[bot] <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>
2026-08-07 17:31:42 +08:00
..
2025-01-29 08:27:07 -08:00
2024-04-05 16:22:59 -07:00

LanceDB Python SDK

A Python library for LanceDB.

Installation

pip install lancedb

Pre-Haswell x86_64 hosts: lancedb-compat

The default lancedb wheel targets x86-64-haswell (AVX2 + FMA + F16C) for full performance on modern hardware. Pre-Haswell hosts — Intel Sandy Bridge / Ivy Bridge / Westmere; AMD Bulldozer / Piledriver / Steamroller — don't have AVX2 and crash with Illegal instruction at import lancedb.

For those hosts, install the lancedb-compat package instead:

pip install lancedb-compat

Same Python API (import lancedb works as usual). The compat wheel is compiled at the x86-64-v2 baseline (Nehalem-class) and uses runtime SIMD dispatch in the embedded lance crate to pick the right kernel tier (scalar / AVX / AVX+FMA / AVX2+FMA / AVX-512) at load time, so it still goes fast on modern hardware while running cleanly on the pre-Haswell silicon. Use lance.simd_info() from Python to verify which tier was selected.

lancedb and lancedb-compat install to the same lancedb/ namespace and conflict at install time. Pick one. To switch, pip uninstall lancedb first, then pip install lancedb-compat (or vice-versa).

If you need a custom baseline (or lancedb-compat isn't yet published for your platform), build from source with the override:

RUSTFLAGS="-C target-cpu=x86-64-v2" maturin build --release
pip install ./target/wheels/lancedb-*.whl

Preview Releases

Stable releases are created about every 2 weeks. For the latest features and bug fixes, you can install the preview release. These releases receive the same level of testing as stable releases, but are not guaranteed to be available for more than 6 months after they are released. Once your application is stable, we recommend switching to stable releases.

pip install --pre --extra-index-url https://pypi.fury.io/lancedb/ lancedb

Usage

Basic Example

import lancedb
db = lancedb.connect('<PATH_TO_LANCEDB_DATASET>')
table = db.open_table('my_table')
results = table.search([0.1, 0.3]).limit(20).to_list()
print(results)

Development

See CONTRIBUTING.md for information on how to contribute to LanceDB.