Igor Ganapolsky
a075aa62f8
## Summary Fixes naive `lit(datetime)` equality filters against table timestamp columns on non-UTC hosts, and adds the integration matrix from #3262. ## Failure (before) On a machine in US Eastern (UTC−4 / EDT), with PyPI `lancedb==0.36.0`: ```python from datetime import datetime import lancedb from lancedb.expr import col, lit db = lancedb.connect("memory://") ts = datetime(2024, 7, 1, 10, 0, 0) # naive table = db.create_table("t", [{"id": 1, "ts": ts}]) rows = table.search().where(col("ts") == lit(ts)).to_list() # actual: [] (0 rows) # expected: 1 row ``` ### Root cause In `python/src/expr.rs`, `expr_lit` converted every `datetime` via Python's `.timestamp()`: - **naive** `.timestamp()` = local wall → UTC epoch (shifted by host offset) - **PyArrow naive** storage = UTC wall-clock microseconds (no local shift) So `lit(naive)` became `CAST('2024-07-01 14:00:00' AS TIMESTAMP)` on EDT while the table held `10:00:00`. ## After Naive datetimes are interpreted as UTC wall clock (`replace(tzinfo=timezone.utc).timestamp()`), matching Arrow storage. Aware datetimes still use `.timestamp()` (correct epoch). Same repro on this branch: **1 matching row**. ## Tests Added `TestExprDatetimeTimezoneIntegration` covering: | Case | Result | |------|--------| | both naive | match | | both same TZ (UTC) | match | | different TZs, same instant | match | | table TZ + naive lit | match (wall clock) | | table naive + aware lit | match | | naive lit SQL is wall clock, not local-shifted | asserts `10:00:00` in SQL | ### Verification ```bash cd python maturin develop pytest python/tests/test_expr.py -v ``` **102 passed** (full `test_expr.py`, including the 6 new cases). Closes #3262 --------- Co-authored-by: Will Jones <willjones127@gmail.com> 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.