Tencent Cloud VectorDB is a fully managed, self-developed, enterprise-level distributed database service designed for storing, retrieving, and analyzing multi-dimensional vector data.
In the walkthrough, we’ll demo the SelfQueryRetriever with a Tencent Cloud VectorDB.

​
create a TencentVectorDB instance

First we’ll want to create a TencentVectorDB and seed it with some data. We’ve created a small demo set of documents that contain summaries of movies. Note: The self-query retriever requires you to have lark installed (pip install lark) along with integration-specific requirements. 
%pip install -qU tcvectordb langchain-openai tiktoken lark

[notice] A new release of pip is available: 23.2.1 -> 24.0
[notice] To update, run: pip install -U pip
Note: you may need to restart the kernel to use updated packages.
We want to use OpenAIEmbeddings so we have to get the OpenAI API Key. 
import getpass
import os

if "OPENAI_API_KEY" not in os.environ:
    os.environ["OPENAI_API_KEY"] = getpass.getpass("OpenAI API Key:")
create a TencentVectorDB instance and seed it with some data: 
from langchain_community.vectorstores.tencentvectordb import (
    ConnectionParams,
    MetaField,
    TencentVectorDB,
)
from langchain_core.documents import Document
from tcvectordb.model.enum import FieldType

meta_fields = [
    MetaField(name="year", data_type="uint64", index=True),
    MetaField(name="rating", data_type="string", index=False),
    MetaField(name="genre", data_type=FieldType.String, index=True),
    MetaField(name="director", data_type=FieldType.String, index=True),
]

docs = [
    Document(
        page_content="The Shawshank Redemption is a 1994 American drama film written and directed by Frank Darabont.",
        metadata={
            "year": 1994,
            "rating": "9.3",
            "genre": "drama",
            "director": "Frank Darabont",
        },
    ),
    Document(
        page_content="The Godfather is a 1972 American crime film directed by Francis Ford Coppola.",
        metadata={
            "year": 1972,
            "rating": "9.2",
            "genre": "crime",
            "director": "Francis Ford Coppola",
        },
    ),
    Document(
        page_content="The Dark Knight is a 2008 superhero film directed by Christopher Nolan.",
        metadata={
            "year": 2008,
            "rating": "9.0",
            "genre": "science fiction",
            "director": "Christopher Nolan",
        },
    ),
    Document(
        page_content="Inception is a 2010 science fiction action film written and directed by Christopher Nolan.",
        metadata={
            "year": 2010,
            "rating": "8.8",
            "genre": "science fiction",
            "director": "Christopher Nolan",
        },
    ),
    Document(
        page_content="The Avengers is a 2012 American superhero film based on the Marvel Comics superhero team of the same name.",
        metadata={
            "year": 2012,
            "rating": "8.0",
            "genre": "science fiction",
            "director": "Joss Whedon",
        },
    ),
    Document(
        page_content="Black Panther is a 2018 American superhero film based on the Marvel Comics character of the same name.",
        metadata={
            "year": 2018,
            "rating": "7.3",
            "genre": "science fiction",
            "director": "Ryan Coogler",
        },
    ),
]

vector_db = TencentVectorDB.from_documents(
    docs,
    None,
    connection_params=ConnectionParams(
        url="http://10.0.X.X",
        key="eC4bLRy2va******************************",
        username="root",
        timeout=20,
    ),
    collection_name="self_query_movies",
    meta_fields=meta_fields,
    drop_old=True,
)

​
Creating our self-querying retriever

Now we can instantiate our retriever. To do this we’ll need to provide some information upfront about the metadata fields that our documents support and a short description of the document contents. 
from langchain.chains.query_constructor.schema import AttributeInfo
from langchain.retrievers.self_query.base import SelfQueryRetriever
from langchain_openai import ChatOpenAI

metadata_field_info = [
    AttributeInfo(
        name="genre",
        description="The genre of the movie",
        type="string",
    ),
    AttributeInfo(
        name="year",
        description="The year the movie was released",
        type="integer",
    ),
    AttributeInfo(
        name="director",
        description="The name of the movie director",
        type="string",
    ),
    AttributeInfo(
        name="rating", description="A 1-10 rating for the movie", type="string"
    ),
]
document_content_description = "Brief summary of a movie"

llm = ChatOpenAI(temperature=0, model="gpt-4", max_tokens=4069)
retriever = SelfQueryRetriever.from_llm(
    llm, vector_db, document_content_description, metadata_field_info, verbose=True
)

​
Test it out

And now we can try actually using our retriever! 
# This example only specifies a relevant query
retriever.invoke("movies about a superhero")

[Document(page_content='The Dark Knight is a 2008 superhero film directed by Christopher Nolan.', metadata={'year': 2008, 'rating': '9.0', 'genre': 'science fiction', 'director': 'Christopher Nolan'}),
 Document(page_content='The Avengers is a 2012 American superhero film based on the Marvel Comics superhero team of the same name.', metadata={'year': 2012, 'rating': '8.0', 'genre': 'science fiction', 'director': 'Joss Whedon'}),
 Document(page_content='Black Panther is a 2018 American superhero film based on the Marvel Comics character of the same name.', metadata={'year': 2018, 'rating': '7.3', 'genre': 'science fiction', 'director': 'Ryan Coogler'}),
 Document(page_content='The Godfather is a 1972 American crime film directed by Francis Ford Coppola.', metadata={'year': 1972, 'rating': '9.2', 'genre': 'crime', 'director': 'Francis Ford Coppola'})]

# This example only specifies a filter
retriever.invoke("movies that were released after 2010")

[Document(page_content='The Avengers is a 2012 American superhero film based on the Marvel Comics superhero team of the same name.', metadata={'year': 2012, 'rating': '8.0', 'genre': 'science fiction', 'director': 'Joss Whedon'}),
 Document(page_content='Black Panther is a 2018 American superhero film based on the Marvel Comics character of the same name.', metadata={'year': 2018, 'rating': '7.3', 'genre': 'science fiction', 'director': 'Ryan Coogler'})]

# This example specifies both a relevant query and a filter
retriever.invoke("movies about a superhero which were released after 2010")

[Document(page_content='The Avengers is a 2012 American superhero film based on the Marvel Comics superhero team of the same name.', metadata={'year': 2012, 'rating': '8.0', 'genre': 'science fiction', 'director': 'Joss Whedon'}),
 Document(page_content='Black Panther is a 2018 American superhero film based on the Marvel Comics character of the same name.', metadata={'year': 2018, 'rating': '7.3', 'genre': 'science fiction', 'director': 'Ryan Coogler'})]

​
Filter k

We can also use the self query retriever to specify k: the number of documents to fetch. We can do this by passing enable_limit=True to the constructor. 
retriever = SelfQueryRetriever.from_llm(
    llm,
    vector_db,
    document_content_description,
    metadata_field_info,
    verbose=True,
    enable_limit=True,
)

retriever.invoke("what are two movies about a superhero")

[Document(page_content='The Dark Knight is a 2008 superhero film directed by Christopher Nolan.', metadata={'year': 2008, 'rating': '9.0', 'genre': 'science fiction', 'director': 'Christopher Nolan'}),
 Document(page_content='The Avengers is a 2012 American superhero film based on the Marvel Comics superhero team of the same name.', metadata={'year': 2012, 'rating': '8.0', 'genre': 'science fiction', 'director': 'Joss Whedon'})]