llama-index-opensolr

LlamaIndex integration for Opensolr — managed Apache Solr as a vector store, with server-side embeddings and native hybrid (BM25 + kNN) search.

No local embedding model. No third-party embedding API key. One set of credentials; vectors are computed on Opensolr's GPU infrastructure (multilingual E5-large-instruct, 1024 dimensions, cosine).

Product page: opensolr.com/langchain · free 15-day trial, no card, at opensolr.com

pip install llama-index-opensolr

Quickstart

from llama_index.core import VectorStoreIndex, StorageContext, Document
from llama_index.vector_stores.opensolr import OpensolrVectorStore
from llama_index.embeddings.opensolr import OpensolrEmbedding

store = OpensolrVectorStore(
    index_name="mysite__dense",
    email="you@example.com",
    api_key="YOUR_OPENSOLR_API_KEY",
    create_if_missing=True,
)
embed_model = OpensolrEmbedding(
    email="you@example.com", api_key="YOUR_OPENSOLR_API_KEY",
    index_name="mysite__dense",
)

index = VectorStoreIndex.from_documents(
    [Document(text="Hybrid search fuses BM25 with vector similarity")],
    storage_context=StorageContext.from_defaults(vector_store=store),
    embed_model=embed_model,
)

retriever = index.as_retriever(similarity_top_k=5)
print(retriever.retrieve("how do keyword and semantic search combine?"))

Hybrid search

Opensolr fuses BM25 and kNN scores per document with its native {!hybrid} Solr query parser:

from llama_index.core.vector_stores.types import VectorStoreQuery, VectorStoreQueryMode

result = store.query(VectorStoreQuery(
    query_str="affordable restaurants",
    similarity_top_k=5,
    mode=VectorStoreQueryMode.HYBRID,
    alpha=0.5,          # 0 = all semantic … 1 = all lexical
))

Metadata filters

Standard LlamaIndex MetadataFilters (EQ, NE, IN, NIN, GT/GTE, LT/LTE) map to Solr fq — and every index is also plain Apache Solr with the native /select API when you need facets, highlighting, or anything beyond retrieval.

Notes

• Vector-enabled indexes run on Opensolr's Solr 9.x environments — currently us (Chicago), de (Germany), fi (Finland). The list is fetched live from the platform; additional dedicated regions can be deployed on request (paid add-on): support@opensolr.com.
• Siblings: langchain-opensolr (LangChain) · opensolr-mcp (MCP server for agents).

MIT license.