lancedb-gatefixer[bot]
b460989753
`MatchQuery(..., fuzziness=None)` raised a Pydantic validation error before a search could run because the field accepted only integers. Allow `Optional[int]`, retain the exact-match default of `0`, and make the documented parameter type explicit. The existing Rust binding already accepts and serializes the optional value. Regression coverage checks construction and JSON serialization for `None`, `0`, `1`, and `2`, plus native indexed searches with the default, explicit exact matching, automatic mode, and one- and two-edit controls. The two `None` regressions reproduced the original constructor error before the fix. Validation against the source-built extension in the locked uv environment: - `uv run --extra tests --extra dev maturin develop --extras tests,dev` - `uv run --no-sync --extra tests --extra dev pytest python/tests/test_fts.py -k 'match_query_fuzziness or fts_query_to_json' -q` — 10 passed. - `uv run --no-sync --extra tests --extra dev pytest python/tests/test_fts.py -q --disable-warnings` — 61 passed. - Locked-environment `ruff check .`, `ruff format .`, and `git diff --check` passed. The reported engine limitation remains observable with pinned Lance `14.0.0-beta.1`: its dataset planner compatibility gate rewrites `None` to zero, so a five-character AUTO query still omits one-edit matches. Automatic expansion for longer terms requires upstream Lance activation. The native acceptance regression uses a two-character term, whose documented automatic distance is zero, while the JSON regression verifies that Python forwards `None` as `null`. This keeps the repair within the issue's requested Python constructor scope. Fixes #4466 <!-- lance-gatekeeper-fix:v1 agent=f5f78166a4f0c7433e7890792b729c3d 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
Threading in CPU-limited containers
LanceDB uses separate pools for compute work and storage I/O. On a container with two visible CPUs, current releases intentionally use one compute worker by default; no manual configuration is needed. If every query logs an I/O core reservation warning on a two-CPU container, upgrade from LanceDB 0.21.1 or earlier.
The two commonly tuned environment variables control different resources:
LANCE_CPU_THREADSoverrides the number of compute workers. One worker is the appropriate setting for a two-CPU container when an explicit override is needed.LANCE_IO_THREADScontrols concurrent storage operations, not reserved CPU cores. Its default can be greater than the number of CPUs because I/O workers spend much of their time waiting for storage.
Keep the defaults unless measurements show that the workload benefits from an override. See the Lance threading model for the current defaults and tuning guidance.
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.