lancedb-gatefixer[bot]
0ba82873c5
## Summary - add a minimized regression for mostly-null `list<float32>` data at the v2.2 structural page boundary - verify scans preserve all 64,885 rows, including 64,668 null list values ## Root cause Lance 3.0.0 sliced repetition/definition state using top-level row offsets in the complex all-null decoder. At this page boundary, the list and validity children were materialized at different lengths. The current Lance dependency contains the upstream decoder repair; this test locks that behavior into the LanceDB Python suite without duplicating decoder logic. ## Validation - reproduced the attached 1,892,466-row case on `lancedb==0.30.0` with `expected 1024 got 285` - verified the full attachment reads on the current branch - `python/.venv/bin/ruff format --check python/python/tests/test_table.py` - `python/.venv/bin/ruff check .` - `cd python && uv run --extra tests pytest python/tests/test_table.py::test_read_mostly_null_list_v2_2_page_boundary -q` - `cd python && uv run --extra tests pytest python/tests/test_table.py -q` (137 passed) Fixes #3194 <!-- lance-gatekeeper-fix:v1 agent=0445adc5303a3302152cea3d2110bed1 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.