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`OllamaEmbeddings.compute_source_embeddings(np.array(["hello", "world"]))` raises a validation error before sending a request. The embedding interface accepts NumPy arrays, but the adapter passes the array directly to Ollama's string-or-sequence request field. Convert NumPy text arrays to lists before the batched request. This preserves input order, the single request, model options and `keep_alive`. The tests cover Unicode/object/sliced arrays, empty input, existing list/Arrow/query inputs and API error propagation. The added input-contract tests also cover two-dimensional arrays and byte strings, with equivalent list inputs as controls. The real Ollama SDK rejects 2-D inputs and invalid UTF-8 locally, before transport. Valid UTF-8 bytes are decoded normally. No extra adapter validation is needed for these cases. Validation on Python 3.12.14 / macOS arm64: - Built the Rust/PyO3 bindings using the repository's uv/maturin environment. - The initial regression run had 5 failures and 4 passing controls on the base; all 9 passed with the fix. With the 6 additional input-contract cases, the related embedding and trust suites now total 55 passed / 11 skipped. - All Python Ruff lint and formatting checks pass. Root checks still report the same 49 lint errors and 11 documentation formatting files reproduced on the untouched base. - Separate review exercised 13 public API cases. Another 7 groups passed through a real loopback HTTP transport, including local validation, UTF-8 serialization and empty-batch model-error propagation. The regression tests use the real Ollama 0.6.2 SDK with HTTPX MockTransport. The loopback check uses an HTTP surrogate, not an Ollama daemon. No live model inference was run. A live Ollama server was unavailable locally. [The current server handler](https://github.com/ollama/ollama/blob/2cd63f7a15039ccd790e97b31edc091fa1707c56/server/routes.go#L1212) explicitly returns HTTP 200 with empty embeddings for empty input after model lookup and runner setup. The adapter preserves the existing empty-list request and its model/setup errors. This is a source check, not a live-server test. Developed with OpenAI Codex, with separate agent review and executed local checks.
LanceDB Python SDK
A Python library for LanceDB.
Installation
pip install lancedb
If no wheel is published for your platform, pip builds lancedb from the source distribution. That build needs a Rust toolchain and protoc (the Protocol Buffers compiler) on your PATH, and can take a while.
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.