mirror of
https://github.com/lancedb/lancedb.git
synced 2025-12-26 14:49:57 +00:00
a0afa84786
Closes #721 fts will return results as a pyarrow table. Pyarrow tables has a `filter` method but it does not take sql filter strings (only pyarrow compute expressions). Instead, we do one of two things to support `tbl.search("keywords").where("foo=5").limit(10).to_arrow()`: Default path: If duckdb is available then use duckdb to execute the sql filter string on the pyarrow table. Backup path: Otherwise, write the pyarrow table to a lance dataset and then do `to_table(filter=<filter>)` Neither is ideal. Default path has two issues: 1. requires installing an extra library (duckdb) 2. duckdb mangles some fields (like fixed size list => list) Backup path incurs a latency penalty (~20ms on ssd) to write the resultset to disk. In the short term, once #676 is addressed, we can write the dataset to "memory://" instead of disk, this makes the post filter evaluate much quicker (ETA next week). In the longer term, we'd like to be able to evaluate the filter string on the pyarrow Table directly, one possibility being that we use Substrait to generate pyarrow compute expressions from sql string. Or if there's enough progress on pyarrow, it could support Substrait expressions directly (no ETA) --------- Co-authored-by: Will Jones <willjones127@gmail.com>
LanceDB
A Python library for LanceDB.
Installation
pip install 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
Create a virtual environment and activate it:
python -m venv venv
. ./venv/bin/activate
Install the necessary packages:
python -m pip install .
To run the unit tests:
pytest
To run linter and automatically fix all errors:
black .
isort .
If any packages are missing, install them with:
pip install <PACKAGE_NAME>
For Windows users, there may be errors when installing packages, so these commands may be helpful:
Activate the virtual environment:
. .\venv\Scripts\activate
You may need to run the installs separately:
pip install -e .[tests]
pip install -e .[dev]
tantivy requires rust to be installed, so install it with conda, as it doesn't support windows installation:
pip install wheel
pip install cargo
conda install rust
pip install tantivy
To run the unit tests:
pytest