lancedb-gatefixer[bot]
123c921c4f
## Summary - add a Python regression for vector search over a sliced Arrow table with nullable scalar columns - verify the nearest row retains its non-null score values after the table is written ## Root cause Lance 0.19.2 deep-copied a validity bitmap without preserving its non-zero bit offset. For a sliced nullable table, scalar values and vectors began at the slice while the copied validity bitmap began at the parent table's first row. That made valid score values appear null even though the corresponding vector stayed intact. The upstream Lance repair is already present in the current dependency; this adds a LanceDB-level guard for the reported create/search path. ## Validation - reproduced on Python 3.12 with LanceDB 0.16.0, pylance 0.19.2, PyArrow 18.0.0, and Polars 1.14.0 - `uv run --project python --extra dev ruff format --check python/python/tests/test_table.py` - `uv run --project python --extra dev ruff check .` - `cd python && uv run --extra tests pytest python/tests/test_table.py::test_search_preserves_nulls_from_sliced_arrow_table -q` Fixes #1879 <!-- lance-gatekeeper-fix:v1 agent=bfa0551793f8e3cf3980cf64ad89908a generation=1 --> Co-authored-by: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>
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.