How do I integrate LlamaIndex with an existing search engine?

Integrating LlamaIndex with an existing search engine involves connecting its data indexing and retrieval capabilities to your search infrastructure. LlamaIndex excels at structuring unstructured data for LLM-based querying, while traditional search engines handle keyword-based or vector-based retrieval. To combine them, you’ll typically use LlamaIndex to preprocess and index your data, then sync those results to your search engine’s index. For example, you might generate vector embeddings with LlamaIndex and store them in a search engine like Elasticsearch or OpenSearch, which supports vector similarity search. This allows you to leverage both keyword matching and semantic search in tandem.

Start by configuring LlamaIndex to process your data into structured formats the search engine can ingest. For instance, use LlamaIndex’s Document and Node classes to split text into chunks, extract metadata, and generate embeddings. Tools like LlamaIndex’s built-in VectorStoreIndex can create embeddings that you’ll export to the search engine via its API or SDK. If your search engine supports hybrid search (combining keywords and vectors), map LlamaIndex’s output to the engine’s schema—for example, storing embeddings in a dense_vector field in Elasticsearch. You’ll also need to ensure synchronization: when source data changes, LlamaIndex should re-index and update the search engine’s records, which could be automated via webhooks or scheduled jobs.

A practical implementation might involve using LlamaIndex to enrich search results. Suppose you’re using Apache Solr for product search. After indexing product descriptions with LlamaIndex, you could store their embeddings in Solr and use a hybrid query to combine Solr’s keyword scoring with cosine similarity from LlamaIndex’s vectors. For LLM-powered features like summarization, use LlamaIndex’s query engines to post-process search results—for example, generating a concise answer from the top 10 matching documents retrieved by the search engine. Libraries like llama-index-readers can help import data from search engines into LlamaIndex for further processing. The key is to treat LlamaIndex as a preprocessing or post-processing layer that complements, rather than replaces, your existing search infrastructure.