# pylint: disable=too-many-lines
from __future__ import annotations
import contextlib
import enum
import logging
import uuid
from typing import (
Any,
AsyncGenerator,
Callable,
Dict,
Generator,
Iterable,
List,
Optional,
Sequence,
Tuple,
Type,
Union,
)
from typing import (
cast as typing_cast,
)
import numpy as np
import sqlalchemy
from langchain_core.documents import Document
from langchain_core.embeddings import Embeddings
from langchain_core.utils import get_from_dict_or_env
from langchain_core.vectorstores import VectorStore
from sqlalchemy import SQLColumnExpression, cast, create_engine, delete, func, select
from sqlalchemy.dialects.postgresql import JSON, JSONB, JSONPATH, UUID, insert
from sqlalchemy.engine import Connection, Engine
from sqlalchemy.ext.asyncio import (
AsyncEngine,
AsyncSession,
async_sessionmaker,
create_async_engine,
)
from sqlalchemy.orm import (
Session,
declarative_base,
relationship,
scoped_session,
sessionmaker,
)
from langchain_postgres._utils import maximal_marginal_relevance
[docs]
class DistanceStrategy(str, enum.Enum):
"""Enumerator of the Distance strategies."""
EUCLIDEAN = "l2"
COSINE = "cosine"
MAX_INNER_PRODUCT = "inner"
DEFAULT_DISTANCE_STRATEGY = DistanceStrategy.COSINE
Base = declarative_base() # type: Any
_LANGCHAIN_DEFAULT_COLLECTION_NAME = "langchain"
_classes: Any = None
COMPARISONS_TO_NATIVE = {
"$eq": "==",
"$ne": "!=",
"$lt": "<",
"$lte": "<=",
"$gt": ">",
"$gte": ">=",
}
SPECIAL_CASED_OPERATORS = {
"$in",
"$nin",
"$between",
"$exists",
}
TEXT_OPERATORS = {
"$like",
"$ilike",
}
LOGICAL_OPERATORS = {"$and", "$or", "$not"}
SUPPORTED_OPERATORS = (
set(COMPARISONS_TO_NATIVE)
.union(TEXT_OPERATORS)
.union(LOGICAL_OPERATORS)
.union(SPECIAL_CASED_OPERATORS)
)
def _get_embedding_collection_store(vector_dimension: Optional[int] = None) -> Any:
global _classes
if _classes is not None:
return _classes
from pgvector.sqlalchemy import Vector # type: ignore
class CollectionStore(Base):
"""Collection store."""
__tablename__ = "langchain_pg_collection"
uuid = sqlalchemy.Column(
UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
)
name = sqlalchemy.Column(sqlalchemy.String, nullable=False, unique=True)
cmetadata = sqlalchemy.Column(JSON)
embeddings = relationship(
"EmbeddingStore",
back_populates="collection",
passive_deletes=True,
)
@classmethod
def get_by_name(
cls, session: Session, name: str
) -> Optional["CollectionStore"]:
return (
session.query(cls)
.filter(typing_cast(sqlalchemy.Column, cls.name) == name)
.first()
)
@classmethod
async def aget_by_name(
cls, session: AsyncSession, name: str
) -> Optional["CollectionStore"]:
return (
(
await session.execute(
select(CollectionStore).where(
typing_cast(sqlalchemy.Column, cls.name) == name
)
)
)
.scalars()
.first()
)
@classmethod
def get_or_create(
cls,
session: Session,
name: str,
cmetadata: Optional[dict] = None,
) -> Tuple["CollectionStore", bool]:
"""Get or create a collection.
Returns:
Where the bool is True if the collection was created.
""" # noqa: E501
created = False
collection = cls.get_by_name(session, name)
if collection:
return collection, created
collection = cls(name=name, cmetadata=cmetadata)
session.add(collection)
session.commit()
created = True
return collection, created
@classmethod
async def aget_or_create(
cls,
session: AsyncSession,
name: str,
cmetadata: Optional[dict] = None,
) -> Tuple["CollectionStore", bool]:
"""
Get or create a collection.
Returns [Collection, bool] where the bool is True if the collection was created.
""" # noqa: E501
created = False
collection = await cls.aget_by_name(session, name)
if collection:
return collection, created
collection = cls(name=name, cmetadata=cmetadata)
session.add(collection)
await session.commit()
created = True
return collection, created
class EmbeddingStore(Base):
"""Embedding store."""
__tablename__ = "langchain_pg_embedding"
id = sqlalchemy.Column(
sqlalchemy.String, nullable=True, primary_key=True, index=True, unique=True
)
collection_id = sqlalchemy.Column(
UUID(as_uuid=True),
sqlalchemy.ForeignKey(
f"{CollectionStore.__tablename__}.uuid",
ondelete="CASCADE",
),
)
collection = relationship(CollectionStore, back_populates="embeddings")
embedding: Vector = sqlalchemy.Column(Vector(vector_dimension))
document = sqlalchemy.Column(sqlalchemy.String, nullable=True)
cmetadata = sqlalchemy.Column(JSONB, nullable=True)
__table_args__ = (
sqlalchemy.Index(
"ix_cmetadata_gin",
"cmetadata",
postgresql_using="gin",
postgresql_ops={"cmetadata": "jsonb_path_ops"},
),
)
_classes = (EmbeddingStore, CollectionStore)
return _classes
def _results_to_docs(docs_and_scores: Any) -> List[Document]:
"""Return docs from docs and scores."""
return [doc for doc, _ in docs_and_scores]
def _create_vector_extension(conn: Connection) -> None:
statement = sqlalchemy.text(
"SELECT pg_advisory_xact_lock(1573678846307946496);"
"CREATE EXTENSION IF NOT EXISTS vector;"
)
conn.execute(statement)
conn.commit()
DBConnection = Union[sqlalchemy.engine.Engine, str]
[docs]
class PGVector(VectorStore):
"""Postgres vector store integration.
Setup:
Install ``langchain_postgres`` and run the docker container.
.. code-block:: bash
pip install -qU langchain-postgres
docker run --name pgvector-container -e POSTGRES_USER=langchain -e POSTGRES_PASSWORD=langchain -e POSTGRES_DB=langchain -p 6024:5432 -d pgvector/pgvector:pg16
Key init args — indexing params:
collection_name: str
Name of the collection.
embeddings: Embeddings
Embedding function to use.
Key init args — client params:
connection: Union[None, DBConnection, Engine, AsyncEngine, str]
Connection string or engine.
Instantiate:
.. code-block:: python
from langchain_postgres import PGVector
from langchain_postgres.vectorstores import PGVector
from langchain_openai import OpenAIEmbeddings
# See docker command above to launch a postgres instance with pgvector enabled.
connection = "postgresql+psycopg://langchain:langchain@localhost:6024/langchain" # Uses psycopg3!
collection_name = "my_docs"
vector_store = PGVector(
embeddings=OpenAIEmbeddings(model="text-embedding-3-large"),
collection_name=collection_name,
connection=connection,
use_jsonb=True,
)
Add Documents:
.. code-block:: python
from langchain_core.documents import Document
document_1 = Document(page_content="foo", metadata={"baz": "bar"})
document_2 = Document(page_content="thud", metadata={"bar": "baz"})
document_3 = Document(page_content="i will be deleted :(")
documents = [document_1, document_2, document_3]
ids = ["1", "2", "3"]
vector_store.add_documents(documents=documents, ids=ids)
Delete Documents:
.. code-block:: python
vector_store.delete(ids=["3"])
Search:
.. code-block:: python
results = vector_store.similarity_search(query="thud",k=1)
for doc in results:
print(f"* {doc.page_content} [{doc.metadata}]")
.. code-block:: python
* thud [{'bar': 'baz'}]
Search with filter:
.. code-block:: python
results = vector_store.similarity_search(query="thud",k=1,filter={"bar": "baz"})
for doc in results:
print(f"* {doc.page_content} [{doc.metadata}]")
.. code-block:: python
* thud [{'bar': 'baz'}]
Search with score:
.. code-block:: python
results = vector_store.similarity_search_with_score(query="qux",k=1)
for doc, score in results:
print(f"* [SIM={score:3f}] {doc.page_content} [{doc.metadata}]")
.. code-block:: python
* [SIM=0.499243] foo [{'baz': 'bar'}]
Async:
.. code-block:: python
# add documents
# await vector_store.aadd_documents(documents=documents, ids=ids)
# delete documents
# await vector_store.adelete(ids=["3"])
# search
# results = vector_store.asimilarity_search(query="thud",k=1)
# search with score
results = await vector_store.asimilarity_search_with_score(query="qux",k=1)
for doc,score in results:
print(f"* [SIM={score:3f}] {doc.page_content} [{doc.metadata}]")
.. code-block:: python
* [SIM=0.499243] foo [{'baz': 'bar'}]
Use as Retriever:
.. code-block:: python
retriever = vector_store.as_retriever(
search_type="mmr",
search_kwargs={"k": 1, "fetch_k": 2, "lambda_mult": 0.5},
)
retriever.invoke("thud")
.. code-block:: python
[Document(metadata={'bar': 'baz'}, page_content='thud')]
""" # noqa: E501
[docs]
def __init__(
self,
embeddings: Embeddings,
*,
connection: Union[None, DBConnection, Engine, AsyncEngine, str] = None,
embedding_length: Optional[int] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
collection_metadata: Optional[dict] = None,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
pre_delete_collection: bool = False,
logger: Optional[logging.Logger] = None,
relevance_score_fn: Optional[Callable[[float], float]] = None,
engine_args: Optional[dict[str, Any]] = None,
use_jsonb: bool = True,
create_extension: bool = True,
async_mode: bool = False,
) -> None:
"""Initialize the PGVector store.
For an async version, use `PGVector.acreate()` instead.
Args:
connection: Postgres connection string or (async)engine.
embeddings: Any embedding function implementing
`langchain.embeddings.base.Embeddings` interface.
embedding_length: The length of the embedding vector. (default: None)
NOTE: This is not mandatory. Defining it will prevent vectors of
any other size to be added to the embeddings table but, without it,
the embeddings can't be indexed.
collection_name: The name of the collection to use. (default: langchain)
NOTE: This is not the name of the table, but the name of the collection.
The tables will be created when initializing the store (if not exists)
So, make sure the user has the right permissions to create tables.
distance_strategy: The distance strategy to use. (default: COSINE)
pre_delete_collection: If True, will delete the collection if it exists.
(default: False). Useful for testing.
engine_args: SQLAlchemy's create engine arguments.
use_jsonb: Use JSONB instead of JSON for metadata. (default: True)
Strongly discouraged from using JSON as it's not as efficient
for querying.
It's provided here for backwards compatibility with older versions,
and will be removed in the future.
create_extension: If True, will create the vector extension if it
doesn't exist. disabling creation is useful when using ReadOnly
Databases.
"""
self.async_mode = async_mode
self.embedding_function = embeddings
self._embedding_length = embedding_length
self.collection_name = collection_name
self.collection_metadata = collection_metadata
self._distance_strategy = distance_strategy
self.pre_delete_collection = pre_delete_collection
self.logger = logger or logging.getLogger(__name__)
self.override_relevance_score_fn = relevance_score_fn
self._engine: Optional[Engine] = None
self._async_engine: Optional[AsyncEngine] = None
self._async_init = False
if isinstance(connection, str):
if async_mode:
self._async_engine = create_async_engine(
connection, **(engine_args or {})
)
else:
self._engine = create_engine(url=connection, **(engine_args or {}))
elif isinstance(connection, Engine):
self.async_mode = False
self._engine = connection
elif isinstance(connection, AsyncEngine):
self.async_mode = True
self._async_engine = connection
else:
raise ValueError(
"connection should be a connection string or an instance of "
"sqlalchemy.engine.Engine or sqlalchemy.ext.asyncio.engine.AsyncEngine"
)
self.session_maker: Union[scoped_session, async_sessionmaker]
if self.async_mode:
self.session_maker = async_sessionmaker(bind=self._async_engine)
else:
self.session_maker = scoped_session(sessionmaker(bind=self._engine))
self.use_jsonb = use_jsonb
self.create_extension = create_extension
if not use_jsonb:
# Replace with a deprecation warning.
raise NotImplementedError("use_jsonb=False is no longer supported.")
if not self.async_mode:
self.__post_init__()
def __post_init__(
self,
) -> None:
"""Initialize the store."""
if self.create_extension:
self.create_vector_extension()
EmbeddingStore, CollectionStore = _get_embedding_collection_store(
self._embedding_length
)
self.CollectionStore = CollectionStore
self.EmbeddingStore = EmbeddingStore
self.create_tables_if_not_exists()
self.create_collection()
async def __apost_init__(
self,
) -> None:
"""Async initialize the store (use lazy approach)."""
if self._async_init: # Warning: possible race condition
return
self._async_init = True
EmbeddingStore, CollectionStore = _get_embedding_collection_store(
self._embedding_length
)
self.CollectionStore = CollectionStore
self.EmbeddingStore = EmbeddingStore
if self.create_extension:
await self.acreate_vector_extension()
await self.acreate_tables_if_not_exists()
await self.acreate_collection()
@property
def embeddings(self) -> Embeddings:
return self.embedding_function
[docs]
def create_vector_extension(self) -> None:
assert self._engine, "engine not found"
try:
with self._engine.connect() as conn:
_create_vector_extension(conn)
except Exception as e:
raise Exception(f"Failed to create vector extension: {e}") from e
[docs]
async def acreate_vector_extension(self) -> None:
assert self._async_engine, "_async_engine not found"
async with self._async_engine.begin() as conn:
await conn.run_sync(_create_vector_extension)
[docs]
def create_tables_if_not_exists(self) -> None:
with self._make_sync_session() as session:
Base.metadata.create_all(session.get_bind())
session.commit()
[docs]
async def acreate_tables_if_not_exists(self) -> None:
assert self._async_engine, "This method must be called with async_mode"
async with self._async_engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all)
[docs]
def drop_tables(self) -> None:
with self._make_sync_session() as session:
Base.metadata.drop_all(session.get_bind())
session.commit()
[docs]
async def adrop_tables(self) -> None:
assert self._async_engine, "This method must be called with async_mode"
await self.__apost_init__() # Lazy async init
async with self._async_engine.begin() as conn:
await conn.run_sync(Base.metadata.drop_all)
[docs]
def create_collection(self) -> None:
if self.pre_delete_collection:
self.delete_collection()
with self._make_sync_session() as session:
self.CollectionStore.get_or_create(
session, self.collection_name, cmetadata=self.collection_metadata
)
session.commit()
[docs]
async def acreate_collection(self) -> None:
await self.__apost_init__() # Lazy async init
async with self._make_async_session() as session:
if self.pre_delete_collection:
await self._adelete_collection(session)
await self.CollectionStore.aget_or_create(
session, self.collection_name, cmetadata=self.collection_metadata
)
await session.commit()
def _delete_collection(self, session: Session) -> None:
collection = self.get_collection(session)
if not collection:
self.logger.warning("Collection not found")
return
session.delete(collection)
async def _adelete_collection(self, session: AsyncSession) -> None:
collection = await self.aget_collection(session)
if not collection:
self.logger.warning("Collection not found")
return
await session.delete(collection)
[docs]
def delete_collection(self) -> None:
with self._make_sync_session() as session:
collection = self.get_collection(session)
if not collection:
self.logger.warning("Collection not found")
return
session.delete(collection)
session.commit()
[docs]
async def adelete_collection(self) -> None:
await self.__apost_init__() # Lazy async init
async with self._make_async_session() as session:
collection = await self.aget_collection(session)
if not collection:
self.logger.warning("Collection not found")
return
await session.delete(collection)
await session.commit()
[docs]
def delete(
self,
ids: Optional[List[str]] = None,
collection_only: bool = False,
**kwargs: Any,
) -> None:
"""Delete vectors by ids or uuids.
Args:
ids: List of ids to delete.
collection_only: Only delete ids in the collection.
"""
with self._make_sync_session() as session:
if ids is not None:
self.logger.debug(
"Trying to delete vectors by ids (represented by the model "
"using the custom ids field)"
)
stmt = delete(self.EmbeddingStore)
if collection_only:
collection = self.get_collection(session)
if not collection:
self.logger.warning("Collection not found")
return
stmt = stmt.where(
self.EmbeddingStore.collection_id == collection.uuid
)
stmt = stmt.where(self.EmbeddingStore.id.in_(ids))
session.execute(stmt)
session.commit()
[docs]
async def adelete(
self,
ids: Optional[List[str]] = None,
collection_only: bool = False,
**kwargs: Any,
) -> None:
"""Async delete vectors by ids or uuids.
Args:
ids: List of ids to delete.
collection_only: Only delete ids in the collection.
"""
await self.__apost_init__() # Lazy async init
async with self._make_async_session() as session:
if ids is not None:
self.logger.debug(
"Trying to delete vectors by ids (represented by the model "
"using the custom ids field)"
)
stmt = delete(self.EmbeddingStore)
if collection_only:
collection = await self.aget_collection(session)
if not collection:
self.logger.warning("Collection not found")
return
stmt = stmt.where(
self.EmbeddingStore.collection_id == collection.uuid
)
stmt = stmt.where(self.EmbeddingStore.id.in_(ids))
await session.execute(stmt)
await session.commit()
[docs]
def get_collection(self, session: Session) -> Any:
assert not self._async_engine, "This method must be called without async_mode"
return self.CollectionStore.get_by_name(session, self.collection_name)
[docs]
async def aget_collection(self, session: AsyncSession) -> Any:
assert self._async_engine, "This method must be called with async_mode"
await self.__apost_init__() # Lazy async init
return await self.CollectionStore.aget_by_name(session, self.collection_name)
@classmethod
def __from(
cls,
texts: List[str],
embeddings: List[List[float]],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
connection: Optional[str] = None,
pre_delete_collection: bool = False,
*,
use_jsonb: bool = True,
**kwargs: Any,
) -> PGVector:
if ids is None:
ids = [str(uuid.uuid4()) for _ in texts]
if not metadatas:
metadatas = [{} for _ in texts]
store = cls(
connection=connection,
collection_name=collection_name,
embeddings=embedding,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
use_jsonb=use_jsonb,
**kwargs,
)
store.add_embeddings(
texts=texts, embeddings=embeddings, metadatas=metadatas, ids=ids, **kwargs
)
return store
@classmethod
async def __afrom(
cls,
texts: List[str],
embeddings: List[List[float]],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
connection: Optional[str] = None,
pre_delete_collection: bool = False,
*,
use_jsonb: bool = True,
**kwargs: Any,
) -> PGVector:
if ids is None:
ids = [str(uuid.uuid1()) for _ in texts]
if not metadatas:
metadatas = [{} for _ in texts]
store = cls(
connection=connection,
collection_name=collection_name,
embeddings=embedding,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
use_jsonb=use_jsonb,
async_mode=True,
**kwargs,
)
await store.aadd_embeddings(
texts=texts, embeddings=embeddings, metadatas=metadatas, ids=ids, **kwargs
)
return store
[docs]
def add_embeddings(
self,
texts: Sequence[str],
embeddings: List[List[float]],
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""Add embeddings to the vectorstore.
Args:
texts: Iterable of strings to add to the vectorstore.
embeddings: List of list of embedding vectors.
metadatas: List of metadatas associated with the texts.
ids: Optional list of ids for the documents.
If not provided, will generate a new id for each document.
kwargs: vectorstore specific parameters
"""
assert not self._async_engine, "This method must be called with sync_mode"
if ids is None:
ids_ = [str(uuid.uuid4()) for _ in texts]
else:
ids_ = [id if id is not None else str(uuid.uuid4()) for id in ids]
if not metadatas:
metadatas = [{} for _ in texts]
with self._make_sync_session() as session: # type: ignore[arg-type]
collection = self.get_collection(session)
if not collection:
raise ValueError("Collection not found")
data = [
{
"id": id,
"collection_id": collection.uuid,
"embedding": embedding,
"document": text,
"cmetadata": metadata or {},
}
for text, metadata, embedding, id in zip(
texts, metadatas, embeddings, ids_
)
]
stmt = insert(self.EmbeddingStore).values(data)
on_conflict_stmt = stmt.on_conflict_do_update(
index_elements=["id"],
# Conflict detection based on these columns
set_={
"embedding": stmt.excluded.embedding,
"document": stmt.excluded.document,
"cmetadata": stmt.excluded.cmetadata,
},
)
session.execute(on_conflict_stmt)
session.commit()
return ids_
[docs]
async def aadd_embeddings(
self,
texts: Sequence[str],
embeddings: List[List[float]],
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""Async add embeddings to the vectorstore.
Args:
texts: Iterable of strings to add to the vectorstore.
embeddings: List of list of embedding vectors.
metadatas: List of metadatas associated with the texts.
ids: Optional list of ids for the texts.
If not provided, will generate a new id for each text.
kwargs: vectorstore specific parameters
"""
await self.__apost_init__() # Lazy async init
if ids is None:
ids_ = [str(uuid.uuid4()) for _ in texts]
else:
ids_ = [id if id is not None else str(uuid.uuid4()) for id in ids]
if not metadatas:
metadatas = [{} for _ in texts]
async with self._make_async_session() as session: # type: ignore[arg-type]
collection = await self.aget_collection(session)
if not collection:
raise ValueError("Collection not found")
data = [
{
"id": id,
"collection_id": collection.uuid,
"embedding": embedding,
"document": text,
"cmetadata": metadata or {},
}
for text, metadata, embedding, id in zip(
texts, metadatas, embeddings, ids_
)
]
stmt = insert(self.EmbeddingStore).values(data)
on_conflict_stmt = stmt.on_conflict_do_update(
index_elements=["id"],
# Conflict detection based on these columns
set_={
"embedding": stmt.excluded.embedding,
"document": stmt.excluded.document,
"cmetadata": stmt.excluded.cmetadata,
},
)
await session.execute(on_conflict_stmt)
await session.commit()
return ids_
[docs]
def add_texts(
self,
texts: Iterable[str],
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""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.
ids: Optional list of ids for the texts.
If not provided, will generate a new id for each text.
kwargs: vectorstore specific parameters
Returns:
List of ids from adding the texts into the vectorstore.
"""
assert not self._async_engine, "This method must be called without async_mode"
texts_ = list(texts)
embeddings = self.embedding_function.embed_documents(texts_)
return self.add_embeddings(
texts=texts_,
embeddings=list(embeddings),
metadatas=list(metadatas) if metadatas else None,
ids=list(ids) if ids else None,
**kwargs,
)
[docs]
async def aadd_texts(
self,
texts: Iterable[str],
metadatas: Optional[List[dict]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""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.
ids: Optional list of ids for the texts.
If not provided, will generate a new id for each text.
kwargs: vectorstore specific parameters
Returns:
List of ids from adding the texts into the vectorstore.
"""
await self.__apost_init__() # Lazy async init
texts_ = list(texts)
embeddings = await self.embedding_function.aembed_documents(texts_)
return await self.aadd_embeddings(
texts=texts_,
embeddings=list(embeddings),
metadatas=list(metadatas) if metadatas else None,
ids=list(ids) if ids else None,
**kwargs,
)
[docs]
def similarity_search(
self,
query: str,
k: int = 4,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Document]:
"""Run similarity search with PGVector with distance.
Args:
query (str): Query text to search for.
k (int): Number of results to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query.
"""
assert not self._async_engine, "This method must be called without async_mode"
embedding = self.embeddings.embed_query(query)
return self.similarity_search_by_vector(
embedding=embedding,
k=k,
filter=filter,
)
[docs]
async def asimilarity_search(
self,
query: str,
k: int = 4,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Document]:
"""Run similarity search with PGVector with distance.
Args:
query (str): Query text to search for.
k (int): Number of results to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query.
"""
await self.__apost_init__() # Lazy async init
embedding = await self.embeddings.aembed_query(query)
return await self.asimilarity_search_by_vector(
embedding=embedding,
k=k,
filter=filter,
)
[docs]
def similarity_search_with_score(
self,
query: str,
k: int = 4,
filter: Optional[dict] = None,
) -> List[Tuple[Document, float]]:
"""Return docs most similar to query.
Args:
query: Text to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query and score for each.
"""
assert not self._async_engine, "This method must be called without async_mode"
embedding = self.embeddings.embed_query(query)
docs = self.similarity_search_with_score_by_vector(
embedding=embedding, k=k, filter=filter
)
return docs
[docs]
async def asimilarity_search_with_score(
self,
query: str,
k: int = 4,
filter: Optional[dict] = None,
) -> List[Tuple[Document, float]]:
"""Return docs most similar to query.
Args:
query: Text to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query and score for each.
"""
await self.__apost_init__() # Lazy async init
embedding = await self.embeddings.aembed_query(query)
docs = await self.asimilarity_search_with_score_by_vector(
embedding=embedding, k=k, filter=filter
)
return docs
@property
def distance_strategy(self) -> Any:
if self._distance_strategy == DistanceStrategy.EUCLIDEAN:
return self.EmbeddingStore.embedding.l2_distance
elif self._distance_strategy == DistanceStrategy.COSINE:
return self.EmbeddingStore.embedding.cosine_distance
elif self._distance_strategy == DistanceStrategy.MAX_INNER_PRODUCT:
return self.EmbeddingStore.embedding.max_inner_product
else:
raise ValueError(
f"Got unexpected value for distance: {self._distance_strategy}. "
f"Should be one of {', '.join([ds.value for ds in DistanceStrategy])}."
)
[docs]
def similarity_search_with_score_by_vector(
self,
embedding: List[float],
k: int = 4,
filter: Optional[dict] = None,
) -> List[Tuple[Document, float]]:
assert not self._async_engine, "This method must be called without async_mode"
results = self.__query_collection(embedding=embedding, k=k, filter=filter)
return self._results_to_docs_and_scores(results)
[docs]
async def asimilarity_search_with_score_by_vector(
self,
embedding: List[float],
k: int = 4,
filter: Optional[dict] = None,
) -> List[Tuple[Document, float]]:
await self.__apost_init__() # Lazy async init
async with self._make_async_session() as session: # type: ignore[arg-type]
results = await self.__aquery_collection(
session=session, embedding=embedding, k=k, filter=filter
)
return self._results_to_docs_and_scores(results)
def _results_to_docs_and_scores(self, results: Any) -> List[Tuple[Document, float]]:
"""Return docs and scores from results."""
docs = [
(
Document(
id=str(result.EmbeddingStore.id),
page_content=result.EmbeddingStore.document,
metadata=result.EmbeddingStore.cmetadata,
),
result.distance if self.embeddings is not None else None,
)
for result in results
]
return docs
def _handle_field_filter(
self,
field: str,
value: Any,
) -> SQLColumnExpression:
"""Create a filter for a specific field.
Args:
field: name of field
value: value to filter
If provided as is then this will be an equality filter
If provided as a dictionary then this will be a filter, the key
will be the operator and the value will be the value to filter by
Returns:
sqlalchemy expression
"""
if not isinstance(field, str):
raise ValueError(
f"field should be a string but got: {type(field)} with value: {field}"
)
if field.startswith("$"):
raise ValueError(
f"Invalid filter condition. Expected a field but got an operator: "
f"{field}"
)
# Allow [a-zA-Z0-9_], disallow $ for now until we support escape characters
if not field.isidentifier():
raise ValueError(
f"Invalid field name: {field}. Expected a valid identifier."
)
if isinstance(value, dict):
# This is a filter specification
if len(value) != 1:
raise ValueError(
"Invalid filter condition. Expected a value which "
"is a dictionary with a single key that corresponds to an operator "
f"but got a dictionary with {len(value)} keys. The first few "
f"keys are: {list(value.keys())[:3]}"
)
operator, filter_value = list(value.items())[0]
# Verify that that operator is an operator
if operator not in SUPPORTED_OPERATORS:
raise ValueError(
f"Invalid operator: {operator}. "
f"Expected one of {SUPPORTED_OPERATORS}"
)
else: # Then we assume an equality operator
operator = "$eq"
filter_value = value
if operator in COMPARISONS_TO_NATIVE:
# Then we implement an equality filter
# native is trusted input
native = COMPARISONS_TO_NATIVE[operator]
return func.jsonb_path_match(
self.EmbeddingStore.cmetadata,
cast(f"$.{field} {native} $value", JSONPATH),
cast({"value": filter_value}, JSONB),
)
elif operator == "$between":
# Use AND with two comparisons
low, high = filter_value
lower_bound = func.jsonb_path_match(
self.EmbeddingStore.cmetadata,
cast(f"$.{field} >= $value", JSONPATH),
cast({"value": low}, JSONB),
)
upper_bound = func.jsonb_path_match(
self.EmbeddingStore.cmetadata,
cast(f"$.{field} <= $value", JSONPATH),
cast({"value": high}, JSONB),
)
return sqlalchemy.and_(lower_bound, upper_bound)
elif operator in {"$in", "$nin", "$like", "$ilike"}:
# We'll do force coercion to text
if operator in {"$in", "$nin"}:
for val in filter_value:
if not isinstance(val, (str, int, float)):
raise NotImplementedError(
f"Unsupported type: {type(val)} for value: {val}"
)
if isinstance(val, bool): # b/c bool is an instance of int
raise NotImplementedError(
f"Unsupported type: {type(val)} for value: {val}"
)
queried_field = self.EmbeddingStore.cmetadata[field].astext
if operator in {"$in"}:
return queried_field.in_([str(val) for val in filter_value])
elif operator in {"$nin"}:
return ~queried_field.in_([str(val) for val in filter_value])
elif operator in {"$like"}:
return queried_field.like(filter_value)
elif operator in {"$ilike"}:
return queried_field.ilike(filter_value)
else:
raise NotImplementedError()
elif operator == "$exists":
if not isinstance(filter_value, bool):
raise ValueError(
"Expected a boolean value for $exists "
f"operator, but got: {filter_value}"
)
condition = func.jsonb_exists(
self.EmbeddingStore.cmetadata,
field,
)
return condition if filter_value else ~condition
else:
raise NotImplementedError()
def _create_filter_clause_deprecated(self, key, value): # type: ignore[no-untyped-def]
"""Deprecated functionality.
This is for backwards compatibility with the JSON based schema for metadata.
It uses incorrect operator syntax (operators are not prefixed with $).
This implementation is not efficient, and has bugs associated with
the way that it handles numeric filter clauses.
"""
IN, NIN, BETWEEN, GT, LT, NE = "in", "nin", "between", "gt", "lt", "ne"
EQ, LIKE, CONTAINS, OR, AND = "eq", "like", "contains", "or", "and"
value_case_insensitive = {k.lower(): v for k, v in value.items()}
if IN in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext.in_(
value_case_insensitive[IN]
)
elif NIN in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext.not_in(
value_case_insensitive[NIN]
)
elif BETWEEN in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext.between(
str(value_case_insensitive[BETWEEN][0]),
str(value_case_insensitive[BETWEEN][1]),
)
elif GT in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext > str(
value_case_insensitive[GT]
)
elif LT in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext < str(
value_case_insensitive[LT]
)
elif NE in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext != str(
value_case_insensitive[NE]
)
elif EQ in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext == str(
value_case_insensitive[EQ]
)
elif LIKE in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext.like(
value_case_insensitive[LIKE]
)
elif CONTAINS in map(str.lower, value):
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext.contains(
value_case_insensitive[CONTAINS]
)
elif OR in map(str.lower, value):
or_clauses = [
self._create_filter_clause(key, sub_value)
for sub_value in value_case_insensitive[OR]
]
filter_by_metadata = sqlalchemy.or_(*or_clauses)
elif AND in map(str.lower, value):
and_clauses = [
self._create_filter_clause(key, sub_value)
for sub_value in value_case_insensitive[AND]
]
filter_by_metadata = sqlalchemy.and_(*and_clauses)
else:
filter_by_metadata = None
return filter_by_metadata
def _create_filter_clause_json_deprecated(
self, filter: Any
) -> List[SQLColumnExpression]:
"""Convert filters from IR to SQL clauses.
**DEPRECATED** This functionality will be deprecated in the future.
It implements translation of filters for a schema that uses JSON
for metadata rather than the JSONB field which is more efficient
for querying.
"""
filter_clauses = []
for key, value in filter.items():
if isinstance(value, dict):
filter_by_metadata = self._create_filter_clause_deprecated(key, value)
if filter_by_metadata is not None:
filter_clauses.append(filter_by_metadata)
else:
filter_by_metadata = self.EmbeddingStore.cmetadata[key].astext == str(
value
)
filter_clauses.append(filter_by_metadata)
return filter_clauses
def _create_filter_clause(self, filters: Any) -> Any:
"""Convert LangChain IR filter representation to matching SQLAlchemy clauses.
At the top level, we still don't know if we're working with a field
or an operator for the keys. After we've determined that we can
call the appropriate logic to handle filter creation.
Args:
filters: Dictionary of filters to apply to the query.
Returns:
SQLAlchemy clause to apply to the query.
"""
if isinstance(filters, dict):
if len(filters) == 1:
# The only operators allowed at the top level are $AND, $OR, and $NOT
# First check if an operator or a field
key, value = list(filters.items())[0]
if key.startswith("$"):
# Then it's an operator
if key.lower() not in ["$and", "$or", "$not"]:
raise ValueError(
f"Invalid filter condition. Expected $and, $or or $not "
f"but got: {key}"
)
else:
# Then it's a field
return self._handle_field_filter(key, filters[key])
if key.lower() == "$and":
if not isinstance(value, list):
raise ValueError(
f"Expected a list, but got {type(value)} for value: {value}"
)
and_ = [self._create_filter_clause(el) for el in value]
if len(and_) > 1:
return sqlalchemy.and_(*and_)
elif len(and_) == 1:
return and_[0]
else:
raise ValueError(
"Invalid filter condition. Expected a dictionary "
"but got an empty dictionary"
)
elif key.lower() == "$or":
if not isinstance(value, list):
raise ValueError(
f"Expected a list, but got {type(value)} for value: {value}"
)
or_ = [self._create_filter_clause(el) for el in value]
if len(or_) > 1:
return sqlalchemy.or_(*or_)
elif len(or_) == 1:
return or_[0]
else:
raise ValueError(
"Invalid filter condition. Expected a dictionary "
"but got an empty dictionary"
)
elif key.lower() == "$not":
if isinstance(value, list):
not_conditions = [
self._create_filter_clause(item) for item in value
]
not_ = sqlalchemy.and_(
*[
sqlalchemy.not_(condition)
for condition in not_conditions
]
)
return not_
elif isinstance(value, dict):
not_ = self._create_filter_clause(value)
return sqlalchemy.not_(not_)
else:
raise ValueError(
f"Invalid filter condition. Expected a dictionary "
f"or a list but got: {type(value)}"
)
else:
raise ValueError(
f"Invalid filter condition. Expected $and, $or or $not "
f"but got: {key}"
)
elif len(filters) > 1:
# Then all keys have to be fields (they cannot be operators)
for key in filters.keys():
if key.startswith("$"):
raise ValueError(
f"Invalid filter condition. Expected a field but got: {key}"
)
# These should all be fields and combined using an $and operator
and_ = [self._handle_field_filter(k, v) for k, v in filters.items()]
if len(and_) > 1:
return sqlalchemy.and_(*and_)
elif len(and_) == 1:
return and_[0]
else:
raise ValueError(
"Invalid filter condition. Expected a dictionary "
"but got an empty dictionary"
)
else:
raise ValueError("Got an empty dictionary for filters.")
else:
raise ValueError(
f"Invalid type: Expected a dictionary but got type: {type(filters)}"
)
def __query_collection(
self,
embedding: List[float],
k: int = 4,
filter: Optional[Dict[str, str]] = None,
) -> Sequence[Any]:
"""Query the collection."""
with self._make_sync_session() as session: # type: ignore[arg-type]
collection = self.get_collection(session)
if not collection:
raise ValueError("Collection not found")
filter_by = [self.EmbeddingStore.collection_id == collection.uuid]
if filter:
if self.use_jsonb:
filter_clauses = self._create_filter_clause(filter)
if filter_clauses is not None:
filter_by.append(filter_clauses)
else:
# Old way of doing things
filter_clauses = self._create_filter_clause_json_deprecated(filter)
filter_by.extend(filter_clauses)
_type = self.EmbeddingStore
results: List[Any] = (
session.query(
self.EmbeddingStore,
self.distance_strategy(embedding).label("distance"),
)
.filter(*filter_by)
.order_by(sqlalchemy.asc("distance"))
.join(
self.CollectionStore,
self.EmbeddingStore.collection_id == self.CollectionStore.uuid,
)
.limit(k)
.all()
)
return results
async def __aquery_collection(
self,
session: AsyncSession,
embedding: List[float],
k: int = 4,
filter: Optional[Dict[str, str]] = None,
) -> Sequence[Any]:
"""Query the collection."""
async with self._make_async_session() as session: # type: ignore[arg-type]
collection = await self.aget_collection(session)
if not collection:
raise ValueError("Collection not found")
filter_by = [self.EmbeddingStore.collection_id == collection.uuid]
if filter:
if self.use_jsonb:
filter_clauses = self._create_filter_clause(filter)
if filter_clauses is not None:
filter_by.append(filter_clauses)
else:
# Old way of doing things
filter_clauses = self._create_filter_clause_json_deprecated(filter)
filter_by.extend(filter_clauses)
_type = self.EmbeddingStore
stmt = (
select(
self.EmbeddingStore,
self.distance_strategy(embedding).label("distance"),
)
.filter(*filter_by)
.order_by(sqlalchemy.asc("distance"))
.join(
self.CollectionStore,
self.EmbeddingStore.collection_id == self.CollectionStore.uuid,
)
.limit(k)
)
results: Sequence[Any] = (await session.execute(stmt)).all()
return results
[docs]
def similarity_search_by_vector(
self,
embedding: List[float],
k: int = 4,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs most similar to embedding vector.
Args:
embedding: Embedding to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query vector.
"""
assert not self._async_engine, "This method must be called without async_mode"
docs_and_scores = self.similarity_search_with_score_by_vector(
embedding=embedding, k=k, filter=filter
)
return _results_to_docs(docs_and_scores)
[docs]
async def asimilarity_search_by_vector(
self,
embedding: List[float],
k: int = 4,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs most similar to embedding vector.
Args:
embedding: Embedding to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List of Documents most similar to the query vector.
"""
assert self._async_engine, "This method must be called with async_mode"
await self.__apost_init__() # Lazy async init
docs_and_scores = await self.asimilarity_search_with_score_by_vector(
embedding=embedding, k=k, filter=filter
)
return _results_to_docs(docs_and_scores)
[docs]
@classmethod
def from_texts(
cls: Type[PGVector],
texts: List[str],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
*,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
use_jsonb: bool = True,
**kwargs: Any,
) -> PGVector:
"""Return VectorStore initialized from documents and embeddings."""
embeddings = embedding.embed_documents(list(texts))
return cls.__from(
texts,
embeddings,
embedding,
metadatas=metadatas,
ids=ids,
collection_name=collection_name,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
use_jsonb=use_jsonb,
**kwargs,
)
[docs]
@classmethod
async def afrom_texts(
cls: Type[PGVector],
texts: List[str],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
*,
use_jsonb: bool = True,
**kwargs: Any,
) -> PGVector:
"""Return VectorStore initialized from documents and embeddings."""
embeddings = await embedding.aembed_documents(list(texts))
return await cls.__afrom(
texts,
embeddings,
embedding,
metadatas=metadatas,
ids=ids,
collection_name=collection_name,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
use_jsonb=use_jsonb,
**kwargs,
)
[docs]
@classmethod
def from_embeddings(
cls,
text_embeddings: List[Tuple[str, List[float]]],
embedding: Embeddings,
*,
metadatas: Optional[List[dict]] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
**kwargs: Any,
) -> PGVector:
"""Construct PGVector wrapper from raw documents and embeddings.
Args:
text_embeddings: List of tuples of text and embeddings.
embedding: Embeddings object.
metadatas: Optional list of metadatas associated with the texts.
collection_name: Name of the collection.
distance_strategy: Distance strategy to use.
ids: Optional list of ids for the documents.
If not provided, will generate a new id for each document.
pre_delete_collection: If True, will delete the collection if it exists.
**Attention**: This will delete all the documents in the existing
collection.
kwargs: Additional arguments.
Returns:
PGVector: PGVector instance.
Example:
.. code-block:: python
from langchain_postgres.vectorstores import PGVector
from langchain_openai.embeddings import OpenAIEmbeddings
embeddings = OpenAIEmbeddings()
text_embeddings = embeddings.embed_documents(texts)
text_embedding_pairs = list(zip(texts, text_embeddings))
vectorstore = PGVector.from_embeddings(text_embedding_pairs, embeddings)
"""
texts = [t[0] for t in text_embeddings]
embeddings = [t[1] for t in text_embeddings]
return cls.__from(
texts,
embeddings,
embedding,
metadatas=metadatas,
ids=ids,
collection_name=collection_name,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
**kwargs,
)
[docs]
@classmethod
async def afrom_embeddings(
cls,
text_embeddings: List[Tuple[str, List[float]]],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
**kwargs: Any,
) -> PGVector:
"""Construct PGVector wrapper from raw documents and pre-
generated embeddings.
Return VectorStore initialized from documents and embeddings.
Postgres connection string is required
"Either pass it as a parameter
or set the PGVECTOR_CONNECTION_STRING environment variable.
Example:
.. code-block:: python
from langchain_community.vectorstores import PGVector
from langchain_community.embeddings import OpenAIEmbeddings
embeddings = OpenAIEmbeddings()
text_embeddings = embeddings.embed_documents(texts)
text_embedding_pairs = list(zip(texts, text_embeddings))
faiss = PGVector.from_embeddings(text_embedding_pairs, embeddings)
"""
texts = [t[0] for t in text_embeddings]
embeddings = [t[1] for t in text_embeddings]
return await cls.__afrom(
texts,
embeddings,
embedding,
metadatas=metadatas,
ids=ids,
collection_name=collection_name,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
**kwargs,
)
[docs]
@classmethod
def from_existing_index(
cls: Type[PGVector],
embedding: Embeddings,
*,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
pre_delete_collection: bool = False,
connection: Optional[DBConnection] = None,
**kwargs: Any,
) -> PGVector:
"""
Get instance of an existing PGVector store.This method will
return the instance of the store without inserting any new
embeddings
"""
store = cls(
connection=connection,
collection_name=collection_name,
embeddings=embedding,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
**kwargs,
)
return store
[docs]
@classmethod
async def afrom_existing_index(
cls: Type[PGVector],
embedding: Embeddings,
*,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
pre_delete_collection: bool = False,
connection: Optional[DBConnection] = None,
**kwargs: Any,
) -> PGVector:
"""
Get instance of an existing PGVector store.This method will
return the instance of the store without inserting any new
embeddings
"""
store = PGVector(
connection=connection,
collection_name=collection_name,
embeddings=embedding,
distance_strategy=distance_strategy,
pre_delete_collection=pre_delete_collection,
async_mode=True,
**kwargs,
)
return store
[docs]
@classmethod
def get_connection_string(cls, kwargs: Dict[str, Any]) -> str:
connection_string: str = get_from_dict_or_env(
data=kwargs,
key="connection",
env_key="PGVECTOR_CONNECTION_STRING",
)
if not connection_string:
raise ValueError(
"Postgres connection string is required"
"Either pass it as a parameter"
"or set the PGVECTOR_CONNECTION_STRING environment variable."
)
return connection_string
[docs]
@classmethod
def from_documents(
cls: Type[PGVector],
documents: List[Document],
embedding: Embeddings,
*,
connection: Optional[DBConnection] = None,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
use_jsonb: bool = True,
**kwargs: Any,
) -> PGVector:
"""Return VectorStore initialized from documents and embeddings."""
texts = [d.page_content for d in documents]
metadatas = [d.metadata for d in documents]
return cls.from_texts(
texts=texts,
pre_delete_collection=pre_delete_collection,
embedding=embedding,
distance_strategy=distance_strategy,
metadatas=metadatas,
connection=connection,
ids=ids,
collection_name=collection_name,
use_jsonb=use_jsonb,
**kwargs,
)
[docs]
@classmethod
async def afrom_documents(
cls: Type[PGVector],
documents: List[Document],
embedding: Embeddings,
collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
ids: Optional[List[str]] = None,
pre_delete_collection: bool = False,
*,
use_jsonb: bool = True,
**kwargs: Any,
) -> PGVector:
"""
Return VectorStore initialized from documents and embeddings.
Postgres connection string is required
"Either pass it as a parameter
or set the PGVECTOR_CONNECTION_STRING environment variable.
"""
texts = [d.page_content for d in documents]
metadatas = [d.metadata for d in documents]
connection_string = cls.get_connection_string(kwargs)
kwargs["connection"] = connection_string
return await cls.afrom_texts(
texts=texts,
pre_delete_collection=pre_delete_collection,
embedding=embedding,
distance_strategy=distance_strategy,
metadatas=metadatas,
ids=ids,
collection_name=collection_name,
use_jsonb=use_jsonb,
**kwargs,
)
[docs]
@classmethod
def connection_string_from_db_params(
cls,
driver: str,
host: str,
port: int,
database: str,
user: str,
password: str,
) -> str:
"""Return connection string from database parameters."""
if driver != "psycopg":
raise NotImplementedError("Only psycopg3 driver is supported")
return f"postgresql+{driver}://{user}:{password}@{host}:{port}/{database}"
def _select_relevance_score_fn(self) -> Callable[[float], float]:
"""
The 'correct' relevance function
may differ depending on a few things, including:
- the distance / similarity metric used by the VectorStore
- the scale of your embeddings (OpenAI's are unit normed. Many others are not!)
- embedding dimensionality
- etc.
"""
if self.override_relevance_score_fn is not None:
return self.override_relevance_score_fn
# Default strategy is to rely on distance strategy provided
# in vectorstore constructor
if self._distance_strategy == DistanceStrategy.COSINE:
return self._cosine_relevance_score_fn
elif self._distance_strategy == DistanceStrategy.EUCLIDEAN:
return self._euclidean_relevance_score_fn
elif self._distance_strategy == DistanceStrategy.MAX_INNER_PRODUCT:
return self._max_inner_product_relevance_score_fn
else:
raise ValueError(
"No supported normalization function"
f" for distance_strategy of {self._distance_strategy}."
"Consider providing relevance_score_fn to PGVector constructor."
)
[docs]
def max_marginal_relevance_search_with_score_by_vector(
self,
embedding: List[float],
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, str]] = None,
**kwargs: Any,
) -> List[Tuple[Document, float]]:
"""Return docs selected using the maximal marginal relevance with score
to embedding vector.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
embedding: Embedding to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Tuple[Document, float]]: List of Documents selected by maximal marginal
relevance to the query and score for each.
"""
assert not self._async_engine, "This method must be called without async_mode"
results = self.__query_collection(embedding=embedding, k=fetch_k, filter=filter)
embedding_list = [result.EmbeddingStore.embedding for result in results]
mmr_selected = maximal_marginal_relevance(
np.array(embedding, dtype=np.float32),
embedding_list,
k=k,
lambda_mult=lambda_mult,
)
candidates = self._results_to_docs_and_scores(results)
return [r for i, r in enumerate(candidates) if i in mmr_selected]
[docs]
async def amax_marginal_relevance_search_with_score_by_vector(
self,
embedding: List[float],
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, str]] = None,
**kwargs: Any,
) -> List[Tuple[Document, float]]:
"""Return docs selected using the maximal marginal relevance with score
to embedding vector.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
embedding: Embedding to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Tuple[Document, float]]: List of Documents selected by maximal marginal
relevance to the query and score for each.
"""
await self.__apost_init__() # Lazy async init
async with self._make_async_session() as session:
results = await self.__aquery_collection(
session=session, embedding=embedding, k=fetch_k, filter=filter
)
embedding_list = [result.EmbeddingStore.embedding for result in results]
mmr_selected = maximal_marginal_relevance(
np.array(embedding, dtype=np.float32),
embedding_list,
k=k,
lambda_mult=lambda_mult,
)
candidates = self._results_to_docs_and_scores(results)
return [r for i, r in enumerate(candidates) if i in mmr_selected]
[docs]
def max_marginal_relevance_search(
self,
query: str,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, str]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs selected using the maximal marginal relevance.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
query (str): Text to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Document]: List of Documents selected by maximal marginal relevance.
"""
embedding = self.embeddings.embed_query(query)
return self.max_marginal_relevance_search_by_vector(
embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
[docs]
async def amax_marginal_relevance_search(
self,
query: str,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, str]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs selected using the maximal marginal relevance.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
query (str): Text to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Document]: List of Documents selected by maximal marginal relevance.
"""
await self.__apost_init__() # Lazy async init
embedding = await self.embeddings.aembed_query(query)
return await self.amax_marginal_relevance_search_by_vector(
embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
[docs]
def max_marginal_relevance_search_with_score(
self,
query: str,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Tuple[Document, float]]:
"""Return docs selected using the maximal marginal relevance with score.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
query (str): Text to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Tuple[Document, float]]: List of Documents selected by maximal marginal
relevance to the query and score for each.
"""
embedding = self.embeddings.embed_query(query)
docs = self.max_marginal_relevance_search_with_score_by_vector(
embedding=embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
return docs
[docs]
async def amax_marginal_relevance_search_with_score(
self,
query: str,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[dict] = None,
**kwargs: Any,
) -> List[Tuple[Document, float]]:
"""Return docs selected using the maximal marginal relevance with score.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
query (str): Text to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Tuple[Document, float]]: List of Documents selected by maximal marginal
relevance to the query and score for each.
"""
await self.__apost_init__() # Lazy async init
embedding = await self.embeddings.aembed_query(query)
docs = await self.amax_marginal_relevance_search_with_score_by_vector(
embedding=embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
return docs
[docs]
def max_marginal_relevance_search_by_vector(
self,
embedding: List[float],
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, str]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs selected using the maximal marginal relevance
to embedding vector.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
embedding (str): Text to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Document]: List of Documents selected by maximal marginal relevance.
"""
docs_and_scores = self.max_marginal_relevance_search_with_score_by_vector(
embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
return _results_to_docs(docs_and_scores)
[docs]
async def amax_marginal_relevance_search_by_vector(
self,
embedding: List[float],
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, str]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs selected using the maximal marginal relevance
to embedding vector.
Maximal marginal relevance optimizes for similarity to query AND diversity
among selected documents.
Args:
embedding (str): Text to look up documents similar to.
k (int): Number of Documents to return. Defaults to 4.
fetch_k (int): Number of Documents to fetch to pass to MMR algorithm.
Defaults to 20.
lambda_mult (float): 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.
filter (Optional[Dict[str, str]]): Filter by metadata. Defaults to None.
Returns:
List[Document]: List of Documents selected by maximal marginal relevance.
"""
await self.__apost_init__() # Lazy async init
docs_and_scores = (
await self.amax_marginal_relevance_search_with_score_by_vector(
embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
)
return _results_to_docs(docs_and_scores)
@contextlib.contextmanager
def _make_sync_session(self) -> Generator[Session, None, None]:
"""Make an async session."""
if self.async_mode:
raise ValueError(
"Attempting to use a sync method in when async mode is turned on. "
"Please use the corresponding async method instead."
)
with self.session_maker() as session:
yield typing_cast(Session, session)
@contextlib.asynccontextmanager
async def _make_async_session(self) -> AsyncGenerator[AsyncSession, None]:
"""Make an async session."""
if not self.async_mode:
raise ValueError(
"Attempting to use an async method in when sync mode is turned on. "
"Please use the corresponding async method instead."
)
async with self.session_maker() as session:
yield typing_cast(AsyncSession, session)
[docs]
def get_by_ids(self, ids: Sequence[str], /) -> List[Document]:
"""Get documents by ids."""
documents = []
with self._make_sync_session() as session:
collection = self.get_collection(session)
filter_by = [self.EmbeddingStore.collection_id == collection.uuid]
stmt = (
select(
self.EmbeddingStore,
)
.where(self.EmbeddingStore.id.in_(ids))
.filter(*filter_by)
)
for result in session.execute(stmt).scalars().all():
documents.append(
Document(
id=result.id,
page_content=result.document,
metadata=result.cmetadata,
)
)
return documents
[docs]
async def aget_by_ids(self, ids: Sequence[str], /) -> List[Document]:
"""Get documents by ids."""
documents = []
async with self._make_async_session() as session:
collection = await self.aget_collection(session)
filter_by = [self.EmbeddingStore.collection_id == collection.uuid]
stmt = (
select(
self.EmbeddingStore,
)
.where(self.EmbeddingStore.id.in_(ids))
.filter(*filter_by)
)
results: Sequence[Any] = (await session.execute(stmt)).scalars().all()
for result in results:
documents.append(
Document(
id=str(result.id),
page_content=result.document,
metadata=result.cmetadata,
)
)
return documents
