lancedb-gatefixer[bot]
c1a3fa7f51
## Summary - add a Python regression test for two partial-schema merge inserts against the same BTree-indexed rows - verify repeated updates retain one copy of every row and the final update values ## Root cause Lance 4.0, used by LanceDB 0.30.2, removed a rewritten fragment from the index bitmap while stale BTree entries for that fragment remained searchable. The next merge found each target through both the stale index and the unindexed-fragment scan, producing the ambiguous-match error. Lance fixed the root cause in lance-format/lance#6563 by applying the fragment-bitmap allow-list to index results, and the Lance release pinned by current LanceDB includes that fix. This test preserves the corrected behavior through the Python API. ## Validation - `cd python && uv run --extra tests pytest python/tests/test_table.py -k merge_insert -q` (9 passed) - `cd python && uv run --extra tests --extra dev ruff format --check python/tests/test_table.py` - `cd python && uv run --extra tests --extra dev ruff check python/tests/test_table.py` Repository-wide Ruff also reports 20 pre-existing violations in untouched CI and plugin scripts. Fixes #3280 <!-- lance-gatekeeper-fix:v1 agent=ee6b9565f9780712026076930566f116 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.