Avanish Garg
bc4c32b779
`optimize()` fails once a tagged version is older than the cleanup cutoff, although the docs say tagged versions are exempt from cleanup, and the failed prune also skips the index-optimize step (repro and numbers in the issue). Change: `OptimizeAction::Prune` already exposes `error_if_tagged_old_versions: Option<bool>`, so no new API. `cleanup_old_versions` and `cleanup_old_versions_before` in `rust/lancedb/src/table/optimize.rs` now use `unwrap_or(false)`, which covers `OptimizeAction::Prune`, `OptimizeAction::All` and `optimize_prune_before`. The Python and Node bindings pass `None`, which now means "retain tagged versions"; I left `python/src/table.rs` and `nodejs/src/table.rs` untouched (this also avoids a conflict with #3870, which edits that region). `Some(true)` still opts in to the error. Doc comments updated; the sentence in `docs/web/management/table.mdx` is accurate once this lands. Tests: Rust `test_optimize_prune_retains_tagged_versions` (`Some(true)` still errors; the default retains the tag; `optimize_prune_before`; `checkout_tag` plus a data read), a Python sync test with a scalar index (index step runs, a second optimize works, untagged versions are pruned, `checkout("release-1")` works), a Python async test and a Node test. **What I could and could not verify (please read):** - I could NOT compile Rust here (not enough disk), so `cargo check`, `cargo test`, the Python/Node binding builds and therefore the fixed-path assertions of the new Rust, Python and Node tests have not been run. This is why the PR is a draft; I will mark it ready once CI is green and fix whatever it finds. - Ran: both new Python tests fail on the released 0.40.0 wheel with the exact error above (so they do catch the bug); pylance 13.0.0 confirms the semantics (`cleanup_old_versions(error_if_tagged_old_versions=False)` removes the untagged versions and keeps the tagged one, still readable with `lance.dataset(version="keep")`); in Lance v14.0.0-beta.7 `cleanup.rs` the policy field is `bool`, the builder default is `true`, and Lance's own `auto_cleanup_hook` uses `Some(false)`; `rustfmt --edition 2024 --check` passes on `optimize.rs`. - The Rust and Node tests rely on timestamp ordering (`nextMillisecond()`, `days(0)`/`now()`), so they could be flaky: tell me if you prefer another approach. Behaviour change: anyone who relied on the error to learn that a tag blocks cleanup now gets a silent retain. Not changed: the deprecated sync `LanceTable.cleanup_old_versions` calls pylance directly and still errors on tagged versions (the keyword may not exist in the oldest supported pylance); `freshness.rs:1377` and `refresh.rs:1077` still pass `None` (I did not check what those paths do with tagged versions). Fixes #4543
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.