Jack YeandXuanwo
2f88b71c21
Stacked on #4173 (diff includes it until that merges; will rebase after). Addresses the token-cache part of [Colin's review](https://github.com/lancedb/lancedb/pull/4173#issuecomment-5674048100). Adds an explicit, opt-in persistent OAuth token cache shared by Rust, Python, and Node clients, plus `login` / `status` / `logout` session APIs, so short-lived processes (CLIs, scripts, notebooks) reuse one session instead of restarting a browser or device flow on every start. - **Opt-in and minimal**: existing callers stay memory-only and lazy. Only refresh tokens are persisted (never access tokens, never client secrets), so there are no local token-expiry decisions to get wrong when clocks move. Each process start performs one silent refresh grant. - **Hardened file backend**: private directory (`0700`), per-record files (`0600`), owner validation, symlink rejection, and atomic `rename` replacement. Corrupt, truncated, unknown-version, or permission-invalid records fail with actionable errors naming the file. Native keyring backends were evaluated (keyring crate routes Linux through D-Bus/zbus: heavy deps, headless/CI flakiness) and are deferred; the file store is the explicit opt-in, not a downgrade from a keyring. - **Cache key**: SHA-256 of the canonical identity (issuer, client ID, sorted/de-duplicated scopes, flow, public/confidential), so no secret appears in a filename and distinct identities never collide. Versioned record schema (`version: 1`). One record per identity: last login wins, documented. - **Cross-process rotation locking**: per-key `fs4` file lock (`flock` / `LockFileEx`) around the refresh critical section — acquire, reread the durable record, refresh exactly once, atomically store the rotated refresh token, release. The OS releases locks on process death, so crashes cannot strand stale locks. Only confirmed `invalid_grant`/`invalid_token` deletes a record and reauthenticates; transport, 5xx, 429, and parse failures retain it. - **Session APIs**: `OAuthSession::login/status/logout` in Rust, `lancedb.remote.OAuthSession` (async) in Python, `OAuthSession` class in Node. `status` returns non-secret metadata only. `logout` removes only the local credential — provider revocation (RFC 7009) is a deliberate follow-up, and local logout never terminates browser SSO. Azure managed identity is rejected for persistence (machine identity stays in memory); client credentials have nothing refreshable to persist and stay memory-only. - No CLI binary exists in this repo, so this ships library APIs plus doc examples in all three languages. Tests: Rust unit + mock-IdP integration (cache-key canonicalization/separation, record versioning/corruption/truncation/symlink/owner/perms, lock serialization + release, two concurrent providers proving no `invalid_grant` and correct rotation, transient-failure retention, `invalid_grant` delete + reauthenticate, login/status/logout lifecycle, client-credentials no-op, IMDS rejection, secret redaction); Python lifecycle + a true two-subprocess cross-process reuse test (second process refreshes once, never hits the device endpoint); Node lifecycle + device-flow login test. Local builds were skipped in development; CI validates all bindings. --------- Co-authored-by: Xuanwo <github@xuanwo.io>
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
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.