Open In Colab

LanceDB Vector Store#

In this notebook we are going to show how to use LanceDB to perform vector searches in LlamaIndex

If you’re opening this Notebook on colab, you will probably need to install LlamaIndex 🦙.

!pip install llama-index

import logging
import sys

# Uncomment to see debug logs
# logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
# logging.getLogger().addHandler(logging.StreamHandler(stream=sys.stdout))

from llama_index import SimpleDirectoryReader, Document, StorageContext
from llama_index.indices.vector_store import VectorStoreIndex
from llama_index.vector_stores import LanceDBVectorStore
import textwrap

Setup OpenAI#

The first step is to configure the openai key. It will be used to created embeddings for the documents loaded into the index

import openai

openai.api_key = ""

Download Data

!mkdir -p 'data/paul_graham/'
!wget 'https://raw.githubusercontent.com/run-llama/llama_index/main/docs/examples/data/paul_graham/paul_graham_essay.txt' -O 'data/paul_graham/paul_graham_essay.txt'

Loading documents#

Load the documents stored in the data/paul_graham/ using the SimpleDirectoryReader

documents = SimpleDirectoryReader("./data/paul_graham/").load_data()
print("Document ID:", documents[0].doc_id, "Document Hash:", documents[0].hash)

Document ID: 855fe1d1-1c1a-4fbe-82ba-6bea663a5920 Document Hash: 4c702b4df575421e1d1af4b1fd50511b226e0c9863dbfffeccb8b689b8448f35

Create the index#

Here we create an index backed by LanceDB using the documents loaded previously. LanceDBVectorStore takes a few arguments.

  • uri (str, required): Location where LanceDB will store its files.

  • table_name (str, optional): The table name where the embeddings will be stored. Defaults to “vectors”.

  • nprobes (int, optional): The number of probes used. A higher number makes search more accurate but also slower. Defaults to 20.

  • refine_factor: (int, optional): Refine the results by reading extra elements and re-ranking them in memory. Defaults to None

  • More details can be found at the LanceDB docs

vector_store = LanceDBVectorStore(uri="/tmp/lancedb")
storage_context = StorageContext.from_defaults(vector_store=vector_store)
index = VectorStoreIndex.from_documents(
    documents, storage_context=storage_context
)

Query the index#

We can now ask questions using our index.

query_engine = index.as_query_engine()
response = query_engine.query("How much did Viaweb charge per month?")

print(textwrap.fill(str(response), 100))

Viaweb charged $100 per month for a small store and $300 per month for a big one.

response = query_engine.query("What did the author do growing up?")

print(textwrap.fill(str(response), 100))

The author worked on writing and programming outside of school before college. They wrote short
stories and tried writing programs on the IBM 1401 computer. They also mentioned getting a
microcomputer, a TRS-80, and started programming on it.

Appending data#

You can also add data to an existing index

del index

index = VectorStoreIndex.from_documents(
    [Document(text="The sky is purple in Portland, Maine")],
    uri="/tmp/new_dataset",
)

query_engine = index.as_query_engine()
response = query_engine.query("Where is the sky purple?")
print(textwrap.fill(str(response), 100))

The sky is purple in Portland, Maine.

index = VectorStoreIndex.from_documents(documents, uri="/tmp/new_dataset")

query_engine = index.as_query_engine()
response = query_engine.query("What companies did the author start?")
print(textwrap.fill(str(response), 100))

The author started two companies: Viaweb and Y Combinator.