Adityaj0
f79dc017c4
## Summary `LanceMergeInsertBuilder.when_not_matched_by_source_delete()` didn't clear a previously-set condition when called again with no argument (or a different condition type). Per the docstring, `condition=None` means "delete all unmatched rows," but if the builder had already been configured with a string/Expr condition, a later no-arg call left the stale condition in place instead of widening the delete to unconditional. Fixes #3767 ## Change Each call now unconditionally sets both `_when_not_matched_by_source_condition` and `_when_not_matched_by_source_condition_expr` (one to the new value, the other to `None`), so the latest call always wins — consistent with every other setter on this builder (e.g. `when_matched_update_all(where=...)`). ## Test plan - [x] New regression test `test_merge_insert_by_source_delete_reconfigure` in `python/python/tests/test_table.py` - [x] `uv run --extra tests pytest python/tests/test_table.py::test_merge_insert_by_source_delete_reconfigure python/tests/test_table.py::test_merge_insert_by_source_delete_expr python/tests/test_table.py::test_merge_insert_by_source_delete_expr_async -vv` — 3 passed - [x] `uv run --extra dev ruff format` / `ruff check` — clean Co-authored-by: Claude Sonnet 5 <noreply@anthropic.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.