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Tobias
1ad97b148b
Closes #4246. lancedb publishes no source distribution, so a platform without a prebuilt wheel (#4104, #4239) has nothing to install. This adds an sdist to the Python release. ## The sdist job The release workflow builds an sdist with the maturin version of the wheel jobs. On a tag, the publish job uploads it with the wheels: to PyPI, and to Fury for beta tags. The job also runs on the pull request dry run, which now starts on a change to `python/pyproject.toml`. ## Checks - The job builds a wheel from the sdist with `--locked` and smoke-tests it in a fresh venv. - `ci/check_sdist.py` fails if a tracked file of the Python package is missing from the tarball. - `twine check --strict` checks that the metadata renders. `pydistcheck` enforces PyPI's 100 MiB size limit. - The unit tests of both check scripts run in the CI scripts workflow. ## Cargo.lock maturin ships the repository lockfile, which pins crates that only the dropped `nodejs` member uses, so `cargo --locked` fails (PyO3/maturin#2609). The job first runs `cargo metadata --locked` on the repository workspace, so a lockfile that has drifted from `Cargo.toml` fails there. It then removes the nodejs-only pins and repacks the sdist. `ci/check_cargo_lock.py` fails if the prune changes any package it keeps, or any dependency of one. The published file is the repacked one. ## Behavior change After the first release with an sdist, pip on a platform with no current wheel builds the newest version from source, which needs a Rust toolchain and `protoc`. Before, pip installed the last version with a wheel for that platform.
77 lines
3.5 KiB
Markdown
77 lines
3.5 KiB
Markdown
# LanceDB Python SDK
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A Python library for [LanceDB](https://github.com/lancedb/lancedb).
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## Installation
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```bash
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pip install lancedb
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```
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If no wheel is published for your platform, pip builds `lancedb` from the source distribution. That build needs a [Rust toolchain](https://rustup.rs/) and [protoc](https://grpc.io/docs/protoc-installation/) (the Protocol Buffers compiler) on your `PATH`, and can take a while.
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### Pre-Haswell x86_64 hosts: `lancedb-compat`
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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`.
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For those hosts, install the `lancedb-compat` package instead:
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```bash
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pip install lancedb-compat
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```
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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.
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`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).
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If you need a custom baseline (or `lancedb-compat` isn't yet published for your platform), build from source with the override:
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```bash
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RUSTFLAGS="-C target-cpu=x86-64-v2" maturin build --release
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pip install ./target/wheels/lancedb-*.whl
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```
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### Preview Releases
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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.
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```bash
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pip install --pre --extra-index-url https://pypi.fury.io/lancedb/ lancedb
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```
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### Threading in CPU-limited containers
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LanceDB uses separate pools for compute work and storage I/O. On a container with
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two visible CPUs, current releases intentionally use one compute worker by default;
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no manual configuration is needed. If every query logs an I/O core reservation
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warning on a two-CPU container, upgrade from LanceDB 0.21.1 or earlier.
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The two commonly tuned environment variables control different resources:
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- `LANCE_CPU_THREADS` overrides the number of compute workers. One worker is the
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appropriate setting for a two-CPU container when an explicit override is needed.
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- `LANCE_IO_THREADS` controls concurrent storage operations, not reserved CPU
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cores. Its default can be greater than the number of CPUs because I/O workers
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spend much of their time waiting for storage.
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Keep the defaults unless measurements show that the workload benefits from an
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override. See the [Lance threading model](https://lance.org/guide/performance/#threading-model)
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for the current defaults and tuning guidance.
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## Usage
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### Basic Example
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```python
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import lancedb
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db = lancedb.connect('<PATH_TO_LANCEDB_DATASET>')
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table = db.open_table('my_table')
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results = table.search([0.1, 0.3]).limit(20).to_list()
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print(results)
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```
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### Development
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See [CONTRIBUTING.md](./CONTRIBUTING.md) for information on how to contribute to LanceDB.
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