Daniel RammerandClaude Opus 5
dd197ad0ff
`LsmWriteSpec::maintained_indexes` becomes `Option<Vec<String>>`. `None` — now the default for a freshly constructed spec — maintains every index the MemWAL supports, resolved when the spec is installed. `Some([])` maintains none, and an explicit list is still taken verbatim. Resolution filters on `IndexConfig::is_memwal_maintainable`, which delegates to lance's `is_maintainable_index_type`. Sweeping up an index the memtable cannot build (a bitmap, say) would fail every memtable claim and leave the table unwritable, so the inferred set excludes them and an explicit list naming one is now rejected up front rather than at claim time. The resolved set is a snapshot, not a subscription: an index created after the spec is installed is not maintained until the spec is unset and set again. That is why the default flipped from "maintain nothing" — an unwanted maintained index costs memory, while a silently unmaintained one degrades FTS to an unscored scan. Note this needs a lance release carrying `is_maintainable_index_type` before it builds against the pinned tag. Co-Authored-By: Claude Opus 5 (1M context) <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.