Files
lancedb/python/tests/test_fts.py
Chang She c8728d4ca1 feat(python): add post filtering for full text search (#739)
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>
2023-12-27 09:31:04 -08:00

150 lines
4.4 KiB
Python

# Copyright 2023 LanceDB Developers
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import os
import random
from unittest import mock
import numpy as np
import pandas as pd
import pytest
import tantivy
import lancedb as ldb
import lancedb.fts
@pytest.fixture
def table(tmp_path) -> ldb.table.LanceTable:
db = ldb.connect(tmp_path)
vectors = [np.random.randn(128) for _ in range(100)]
nouns = ("puppy", "car", "rabbit", "girl", "monkey")
verbs = ("runs", "hits", "jumps", "drives", "barfs")
adv = ("crazily.", "dutifully.", "foolishly.", "merrily.", "occasionally.")
adj = ("adorable", "clueless", "dirty", "odd", "stupid")
text = [
" ".join(
[
nouns[random.randrange(0, 5)],
verbs[random.randrange(0, 5)],
adv[random.randrange(0, 5)],
adj[random.randrange(0, 5)],
]
)
for _ in range(100)
]
table = db.create_table(
"test",
data=pd.DataFrame(
{
"vector": vectors,
"id": [i % 2 for i in range(100)],
"text": text,
"text2": text,
"nested": [{"text": t} for t in text],
}
),
)
return table
def test_create_index(tmp_path):
index = ldb.fts.create_index(str(tmp_path / "index"), ["text"])
assert isinstance(index, tantivy.Index)
assert os.path.exists(str(tmp_path / "index"))
def test_populate_index(tmp_path, table):
index = ldb.fts.create_index(str(tmp_path / "index"), ["text"])
assert ldb.fts.populate_index(index, table, ["text"]) == len(table)
def test_search_index(tmp_path, table):
index = ldb.fts.create_index(str(tmp_path / "index"), ["text"])
ldb.fts.populate_index(index, table, ["text"])
index.reload()
results = ldb.fts.search_index(index, query="puppy", limit=10)
assert len(results) == 2
assert len(results[0]) == 10 # row_ids
assert len(results[1]) == 10 # _distance
def test_create_index_from_table(tmp_path, table):
table.create_fts_index("text")
df = table.search("puppy").limit(10).select(["text"]).to_pandas()
assert len(df) == 10
assert "text" in df.columns
# Check whether it can be updated
table.add(
[
{
"vector": np.random.randn(128),
"id": 101,
"text": "gorilla",
"text2": "gorilla",
"nested": {"text": "gorilla"},
}
]
)
with pytest.raises(ValueError, match="already exists"):
table.create_fts_index("text")
table.create_fts_index("text", replace=True)
assert len(table.search("gorilla").limit(1).to_pandas()) == 1
def test_create_index_multiple_columns(tmp_path, table):
table.create_fts_index(["text", "text2"])
df = table.search("puppy").limit(10).to_pandas()
assert len(df) == 10
assert "text" in df.columns
assert "text2" in df.columns
def test_empty_rs(tmp_path, table, mocker):
table.create_fts_index(["text", "text2"])
mocker.patch("lancedb.fts.search_index", return_value=([], []))
df = table.search("puppy").limit(10).to_pandas()
assert len(df) == 0
def test_nested_schema(tmp_path, table):
table.create_fts_index("nested.text")
rs = table.search("puppy").limit(10).to_list()
assert len(rs) == 10
def test_search_index_with_filter(table):
table.create_fts_index("text")
orig_import = __import__
def import_mock(name, *args):
if name == "duckdb":
raise ImportError
return orig_import(name, *args)
# no duckdb
with mock.patch("builtins.__import__", side_effect=import_mock):
rs = table.search("puppy").where("id=1").limit(10).to_list()
for r in rs:
assert r["id"] == 1
# yes duckdb
rs2 = table.search("puppy").where("id=1").limit(10).to_list()
for r in rs2:
assert r["id"] == 1
assert rs == rs2