lancedb-gatefixer[bot]
e84afa7bac
Python sync remote searches default `fast_search` to `False` and omitted full-text search columns to `None`, while local searches leave fast search unset and use `[]`. This makes otherwise identical `to_query_object()` results depend on the backend. Align these omitted defaults in `RemoteTable.search` while preserving explicit fast-search settings. Keep the shared vector-column inference and automatic FTS fallback provided by the base branch. Regression tests compare complete local and remote query objects for both reported vector dimensions, NumPy and batch vectors, explicit columns, scans, and full-text queries. They also cover matching ambiguity errors, explicit fast-search values, automatic FTS without embeddings, and automatic vector search with embedding metadata, using the shared remote fixture. Validation after merging `main` at `bbc4aebe`: - `cd python && uv run --no-sync --extra tests pytest python/tests/test_remote_db.py -q`: 128 passed. - `cd python && uv run --no-sync --extra tests pytest python/tests/test_query.py python/tests/test_table.py -q -k 'query_serialization or async_search_without_query or none_query or nprobes_zero or empty_vector'`: 27 passed. - `ruff format .` and `ruff check .` from the repository root (Ruff 0.9.9): passed. - `git diff --check`: passed. Fixes #4391 <!-- lance-gatekeeper-fix:v1 agent=7cad560371d7aa64fb2511e510dd1bfd 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.