lancedb-gatefixer[bot]
7357d63e87
<!-- lance-gatekeeper-fix:v1 agent=5c80c44c083b3b8ad0da595419d468fc generation=1 --> ## Root cause The legacy synchronous Python table called `delete` on a shared, mutable `lance.Dataset`. Concurrent table operations could hold a PyO3 borrow while delete requested an exclusive borrow, producing `RuntimeError: Already borrowed`. The current async-backed binding fixes this by cloning its thread-safe Rust table handle before awaiting, but that concurrency contract had no regression coverage. ## Fix - Document why delete must clone the Rust table handle before entering its async future. - Add a barrier-synchronized regression test that deletes distinct rows through one shared table from eight Python threads. - Verify every delete commits exactly one row, every commit gets a distinct version, and no rows remain. ## Validation - `cargo check --quiet --features remote --tests --examples` - `cargo fmt --all -- --check` - `uv run --extra tests --extra dev ruff format --check python/tests/test_table.py` - `uv run --extra tests --extra dev ruff check python/tests/test_table.py` - `uv run --extra tests --extra dev pytest python/tests/test_table.py::test_concurrent_deletes_are_thread_safe python/tests/test_table.py::test_delete python/tests/test_table.py::test_delete_expr python/tests/test_table.py::test_delete_expr_async -q` (4 passed) - Manual stress reproduction: 100 concurrent deletes on one table completed at versions 2–101 with zero rows remaining. Fixes #530 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.