Llama-Index

Quick start

You would need to install the integration via pip install llama-index-vector-stores-lancedb in order to use it. You can run the below script to try it out :

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.core import SimpleDirectoryReader, Document, StorageContext
from llama_index.core import VectorStoreIndex
from llama_index.vector_stores.lancedb import LanceDBVectorStore
import textwrap
import openai

openai.api_key = "sk-..."

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

## For LanceDB cloud :
# vector_store = LanceDBVectorStore( 
#     uri="db://db_name", # your remote DB URI
#     api_key="sk_..", # lancedb cloud api key
#     region="your-region" # the region you configured
#     ...
# )

vector_store = LanceDBVectorStore(
    uri="./lancedb", mode="overwrite", query_type="vector"
)
storage_context = StorageContext.from_defaults(vector_store=vector_store)

index = VectorStoreIndex.from_documents(
    documents, storage_context=storage_context
)
lance_filter = "metadata.file_name = 'paul_graham_essay.txt' "
retriever = index.as_retriever(vector_store_kwargs={"where": lance_filter})
response = retriever.retrieve("What did the author do growing up?")

Checkout Complete example here - LlamaIndex demo

Filtering

For metadata filtering, you can use a Lance SQL-like string filter as demonstrated in the example above. Additionally, you can also filter using the MetadataFilters class from LlamaIndex:

from llama_index.core.vector_stores import (
    MetadataFilters,
    FilterOperator,
    FilterCondition,
    MetadataFilter,
)

query_filters = MetadataFilters(
    filters=[
        MetadataFilter(
            key="creation_date", operator=FilterOperator.EQ, value="2024-05-23"
        ),
        MetadataFilter(
            key="file_size", value=75040, operator=FilterOperator.GT
        ),
    ],
    condition=FilterCondition.AND,
)

Hybrid Search

For complete documentation, refer here. This example uses the colbert reranker. Make sure to install necessary dependencies for the reranker you choose.

from lancedb.rerankers import ColbertReranker

reranker = ColbertReranker()
vector_store._add_reranker(reranker)

query_engine = index.as_query_engine(
    filters=query_filters,
    vector_store_kwargs={
        "query_type": "hybrid",
    }
)

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

In the above snippet, you can change/specify query_type again when creating the engine/retriever.

API reference

The exhaustive list of parameters for LanceDBVectorStore vector store are :
- connection: Optional, lancedb.db.LanceDBConnection connection object to use. If not provided, a new connection will be created. - uri: Optional[str], the uri of your database. Defaults to "/tmp/lancedb". - table_name : Optional[str], Name of your table in the database. Defaults to "vectors". - table: Optional[Any], lancedb.db.LanceTable object to be passed. Defaults to None. - vector_column_name: Optional[Any], Column name to use for vector's in the table. Defaults to 'vector'.
- doc_id_key: Optional[str], Column name to use for document id's in the table. Defaults to 'doc_id'.
- text_key: Optional[str], Column name to use for text in the table. Defaults to 'text'.
- api_key: Optional[str], API key to use for LanceDB cloud database. Defaults to None.
- region: Optional[str], Region to use for LanceDB cloud database. Only for LanceDB Cloud, defaults to None.
- nprobes : Optional[int], Set the number of probes to use. Only applicable if ANN index is created on the table else its ignored. Defaults to 20. - refine_factor : Optional[int], Refine the results by reading extra elements and re-ranking them in memory. Defaults to None. - reranker: Optional[Any], The reranker to use for LanceDB. Defaults to None. - overfetch_factor: Optional[int], The factor by which to fetch more results. Defaults to 1. - mode: Optional[str], The mode to use for LanceDB. Defaults to "overwrite". - query_type:Optional[str], The type of query to use for LanceDB. Defaults to "vector".

Methods

• from_table(cls, table: lancedb.db.LanceTable) -> LanceDBVectorStore : (class method) Creates instance from lancedb table.

• _add_reranker(self, reranker: lancedb.rerankers.Reranker) -> None : Add a reranker to an existing vector store.

  • Usage :

    from lancedb.rerankers import ColbertReranker
    reranker = ColbertReranker()
    vector_store._add_reranker(reranker)
    

• _table_exists(self, tbl_name: Optional[str] = None) -> bool : Returns True if tbl_name exists in database.

• create_index(
  self, scalar: Optional[bool] = False, col_name: Optional[str] = None, num_partitions: Optional[int] = 256, num_sub_vectors: Optional[int] = 96, index_cache_size: Optional[int] = None, metric: Optional[str] = "l2",
  ) -> None : Creates a scalar(for non-vector cols) or a vector index on a table. Make sure your vector column has enough data before creating an index on it.

• add(self, nodes: List[BaseNode], **add_kwargs: Any, ) -> List[str] : adds Nodes to the table

• delete(self, ref_doc_id: str) -> None: Delete nodes using with node_ids.

• delete_nodes(self, node_ids: List[str]) -> None : Delete nodes using with node_ids.
• query( self, query: VectorStoreQuery, **kwargs: Any, ) -> VectorStoreQueryResult: Query index(VectorStoreIndex) for top k most similar nodes. Accepts llamaIndex VectorStoreQuery object.