Files
lancedb/python
Xuanwo a588208de6 feat: add scalar function authoring and catalog client (#3991)
## Problem

The canonical Function wire values and typed remote Job contract do not
yet provide a Python authoring surface or catalog client, so users
cannot package a scalar callable, register it, or reopen the exact
immutable Function version.

## Behavior

This adds scalar-only `@udf` authoring with deterministic annotation or
explicit Arrow schema validation, content-addressed Python artifacts,
and an internal scalar-to-Arrow-batch adapter descriptor. Registration
payloads model non-secret environment values and secret names only.

Remote connections can submit `create_function_async` and receive a
typed `Job<FunctionVersion>`, then reopen that exact version by name and
version ID. Synchronous connections can call `create_function` to submit
and wait for the immutable version in one operation. Local Function
catalog operations return a stable `NotSupported` error. Shared
Rust/Python golden payloads and mocked catalog responses freeze the
request, typed terminal result, and exact lookup contract.

## Validation

- Rust formatting, remote check, clippy, and focused LDB-1/LDB-2 tests
- Python formatting, lint, and focused LDB-1/LDB-2 tests
- Python API documentation build
2026-08-21 17:19:13 +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.