Daniel RammerandClaude Opus 5
c09e808dab
`get_lsm_stats` reported four table-level rollups, three per-bucket derived fields, and two pieces of in-process state. All of it is either arithmetic the caller can do on the per-bucket list (`bucket_count`, `generations_total`, `l0_bytes_total`, `memtable_rows_total`, `l0_bytes`, `wal_lag`) or a value that is true only for the microsecond it was read (`fenced`, `compaction_in_progress`). Drop them. What is left is measured: manifest metadata, one entry per flushed L0 generation, and one entry per in-memory memtable. Three shape changes follow: * `active_memtable` + `frozen_memtables` collapse into `memtables`, ordered oldest first with the active one last. Absent — not empty — for a `Sealed` bucket, whose writer is torn down. * Generation `rows` is unconditional, so `LsmStatsOptions` and its `include_generation_rows` flag are gone. A row count that had to be asked for was routinely absent from the one report that needed it. * `memtable_indexes` becomes a list of names on each memtable, since each carries its own index store and a frozen one predates an index created after it froze. 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.