from __future__ import annotations
import logging
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
Generator,
Iterable,
List,
Optional,
Tuple,
TypeVar,
Union,
)
import numpy as np
from langchain_core._api.deprecation import deprecated
from langchain_core.documents import Document
from langchain_core.embeddings import Embeddings
from langchain_core.vectorstores import VectorStore
from langchain_community.vectorstores.utils import maximal_marginal_relevance
if TYPE_CHECKING:
from pymongo.collection import Collection
MongoDBDocumentType = TypeVar("MongoDBDocumentType", bound=Dict[str, Any])
logger = logging.getLogger(__name__)
DEFAULT_INSERT_BATCH_SIZE = 100
[docs]
@deprecated(
since="0.0.25",
removal="1.0",
alternative_import="langchain_mongodb.MongoDBAtlasVectorSearch",
)
class MongoDBAtlasVectorSearch(VectorStore):
"""`MongoDB Atlas Vector Search` vector store.
To use, you should have both:
- the ``pymongo`` python package installed
- a connection string associated with a MongoDB Atlas Cluster having deployed an
Atlas Search index
Example:
.. code-block:: python
from langchain_community.vectorstores import MongoDBAtlasVectorSearch
from langchain_community.embeddings.openai import OpenAIEmbeddings
from pymongo import MongoClient
mongo_client = MongoClient("<YOUR-CONNECTION-STRING>")
collection = mongo_client["<db_name>"]["<collection_name>"]
embeddings = OpenAIEmbeddings()
vectorstore = MongoDBAtlasVectorSearch(collection, embeddings)
"""
[docs]
def __init__(
self,
collection: Collection[MongoDBDocumentType],
embedding: Embeddings,
*,
index_name: str = "default",
text_key: str = "text",
embedding_key: str = "embedding",
relevance_score_fn: str = "cosine",
):
"""
Args:
collection: MongoDB collection to add the texts to.
embedding: Text embedding model to use.
text_key: MongoDB field that will contain the text for each
document.
embedding_key: MongoDB field that will contain the embedding for
each document.
index_name: Name of the Atlas Search index.
relevance_score_fn: The similarity score used for the index.
Currently supported: Euclidean, cosine, and dot product.
"""
self._collection = collection
self._embedding = embedding
self._index_name = index_name
self._text_key = text_key
self._embedding_key = embedding_key
self._relevance_score_fn = relevance_score_fn
@property
def embeddings(self) -> Embeddings:
return self._embedding
def _select_relevance_score_fn(self) -> Callable[[float], float]:
if self._relevance_score_fn == "euclidean":
return self._euclidean_relevance_score_fn
elif self._relevance_score_fn == "dotProduct":
return self._max_inner_product_relevance_score_fn
elif self._relevance_score_fn == "cosine":
return self._cosine_relevance_score_fn
else:
raise NotImplementedError(
f"No relevance score function for ${self._relevance_score_fn}"
)
[docs]
@classmethod
def from_connection_string(
cls,
connection_string: str,
namespace: str,
embedding: Embeddings,
**kwargs: Any,
) -> MongoDBAtlasVectorSearch:
"""Construct a `MongoDB Atlas Vector Search` vector store
from a MongoDB connection URI.
Args:
connection_string: A valid MongoDB connection URI.
namespace: A valid MongoDB namespace (database and collection).
embedding: The text embedding model to use for the vector store.
Returns:
A new MongoDBAtlasVectorSearch instance.
"""
try:
from importlib.metadata import version
from pymongo import MongoClient
from pymongo.driver_info import DriverInfo
except ImportError:
raise ImportError(
"Could not import pymongo, please install it with "
"`pip install pymongo`."
)
client: MongoClient = MongoClient(
connection_string,
driver=DriverInfo(name="Langchain", version=version("langchain")),
)
db_name, collection_name = namespace.split(".")
collection = client[db_name][collection_name]
return cls(collection, embedding, **kwargs)
[docs]
def add_texts(
self,
texts: Iterable[str],
metadatas: Optional[List[Dict[str, Any]]] = None,
**kwargs: Any,
) -> List:
"""Run more texts through the embeddings and add to the vectorstore.
Args:
texts: Iterable of strings to add to the vectorstore.
metadatas: Optional list of metadatas associated with the texts.
Returns:
List of ids from adding the texts into the vectorstore.
"""
batch_size = kwargs.get("batch_size", DEFAULT_INSERT_BATCH_SIZE)
_metadatas: Union[List, Generator] = metadatas or ({} for _ in texts)
texts_batch = []
metadatas_batch = []
result_ids = []
for i, (text, metadata) in enumerate(zip(texts, _metadatas)):
texts_batch.append(text)
metadatas_batch.append(metadata)
if (i + 1) % batch_size == 0:
result_ids.extend(self._insert_texts(texts_batch, metadatas_batch))
texts_batch = []
metadatas_batch = []
if texts_batch:
result_ids.extend(self._insert_texts(texts_batch, metadatas_batch))
return result_ids
def _insert_texts(self, texts: List[str], metadatas: List[Dict[str, Any]]) -> List:
if not texts:
return []
# Embed and create the documents
embeddings = self._embedding.embed_documents(texts)
to_insert = [
{self._text_key: t, self._embedding_key: embedding, **m}
for t, m, embedding in zip(texts, metadatas, embeddings)
]
# insert the documents in MongoDB Atlas
insert_result = self._collection.insert_many(to_insert) # type: ignore
return insert_result.inserted_ids
def _similarity_search_with_score(
self,
embedding: List[float],
k: int = 4,
pre_filter: Optional[Dict] = None,
post_filter_pipeline: Optional[List[Dict]] = None,
) -> List[Tuple[Document, float]]:
params = {
"queryVector": embedding,
"path": self._embedding_key,
"numCandidates": k * 10,
"limit": k,
"index": self._index_name,
}
if pre_filter:
params["filter"] = pre_filter
query = {"$vectorSearch": params}
pipeline = [
query,
{"$set": {"score": {"$meta": "vectorSearchScore"}}},
]
if post_filter_pipeline is not None:
pipeline.extend(post_filter_pipeline)
cursor = self._collection.aggregate(pipeline) # type: ignore[arg-type]
docs = []
for res in cursor:
text = res.pop(self._text_key)
score = res.pop("score")
docs.append((Document(page_content=text, metadata=res), score))
return docs
[docs]
def similarity_search_with_score(
self,
query: str,
k: int = 4,
pre_filter: Optional[Dict] = None,
post_filter_pipeline: Optional[List[Dict]] = None,
) -> List[Tuple[Document, float]]:
"""Return MongoDB documents most similar to the given query and their scores.
Uses the vectorSearch operator available in MongoDB Atlas Search.
For more: https://www.mongodb.com/docs/atlas/atlas-vector-search/vector-search-stage/
Args:
query: Text to look up documents similar to.
k: (Optional) number of documents to return. Defaults to 4.
pre_filter: (Optional) dictionary of argument(s) to prefilter document
fields on.
post_filter_pipeline: (Optional) Pipeline of MongoDB aggregation stages
following the vectorSearch stage.
Returns:
List of documents most similar to the query and their scores.
"""
embedding = self._embedding.embed_query(query)
docs = self._similarity_search_with_score(
embedding,
k=k,
pre_filter=pre_filter,
post_filter_pipeline=post_filter_pipeline,
)
return docs
[docs]
def similarity_search(
self,
query: str,
k: int = 4,
pre_filter: Optional[Dict] = None,
post_filter_pipeline: Optional[List[Dict]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return MongoDB documents most similar to the given query.
Uses the vectorSearch operator available in MongoDB Atlas Search.
For more: https://www.mongodb.com/docs/atlas/atlas-vector-search/vector-search-stage/
Args:
query: Text to look up documents similar to.
k: (Optional) number of documents to return. Defaults to 4.
pre_filter: (Optional) dictionary of argument(s) to prefilter document
fields on.
post_filter_pipeline: (Optional) Pipeline of MongoDB aggregation stages
following the vectorSearch stage.
Returns:
List of documents most similar to the query and their scores.
"""
additional = kwargs.get("additional")
docs_and_scores = self.similarity_search_with_score(
query,
k=k,
pre_filter=pre_filter,
post_filter_pipeline=post_filter_pipeline,
)
if additional and "similarity_score" in additional:
for doc, score in docs_and_scores:
doc.metadata["score"] = score
return [doc for doc, _ in docs_and_scores]
[docs]
def max_marginal_relevance_search(
self,
query: str,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
pre_filter: Optional[Dict] = None,
post_filter_pipeline: Optional[List[Dict]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return documents selected using the maximal marginal relevance.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
query: Text to look up documents similar to.
k: (Optional) number of documents to return. Defaults to 4.
fetch_k: (Optional) number of documents to fetch before passing to MMR
algorithm. Defaults to 20.
lambda_mult: Number between 0 and 1 that determines the degree
of diversity among the results with 0 corresponding
to maximum diversity and 1 to minimum diversity.
Defaults to 0.5.
pre_filter: (Optional) dictionary of argument(s) to prefilter on document
fields.
post_filter_pipeline: (Optional) pipeline of MongoDB aggregation stages
following the vectorSearch stage.
Returns:
List of documents selected by maximal marginal relevance.
"""
query_embedding = self._embedding.embed_query(query)
docs = self._similarity_search_with_score(
query_embedding,
k=fetch_k,
pre_filter=pre_filter,
post_filter_pipeline=post_filter_pipeline,
)
mmr_doc_indexes = maximal_marginal_relevance(
np.array(query_embedding),
[doc.metadata[self._embedding_key] for doc, _ in docs],
k=k,
lambda_mult=lambda_mult,
)
mmr_docs = [docs[i][0] for i in mmr_doc_indexes]
return mmr_docs
[docs]
@classmethod
def from_texts(
cls,
texts: List[str],
embedding: Embeddings,
metadatas: Optional[List[Dict]] = None,
collection: Optional[Collection[MongoDBDocumentType]] = None,
**kwargs: Any,
) -> MongoDBAtlasVectorSearch:
"""Construct a `MongoDB Atlas Vector Search` vector store from raw documents.
This is a user-friendly interface that:
1. Embeds documents.
2. Adds the documents to a provided MongoDB Atlas Vector Search index
(Lucene)
This is intended to be a quick way to get started.
Example:
.. code-block:: python
from pymongo import MongoClient
from langchain_community.vectorstores import MongoDBAtlasVectorSearch
from langchain_community.embeddings import OpenAIEmbeddings
mongo_client = MongoClient("<YOUR-CONNECTION-STRING>")
collection = mongo_client["<db_name>"]["<collection_name>"]
embeddings = OpenAIEmbeddings()
vectorstore = MongoDBAtlasVectorSearch.from_texts(
texts,
embeddings,
metadatas=metadatas,
collection=collection
)
"""
if collection is None:
raise ValueError("Must provide 'collection' named parameter.")
vectorstore = cls(collection, embedding, **kwargs)
vectorstore.add_texts(texts, metadatas=metadatas)
return vectorstore
