Hybrid Search and Reranking in .NET with Qdrant: Advanced RAG

Learn hybrid search in .NET: build an advanced RAG retrieval pipeline with ASP.NET Core, Qdrant, BM25, Reciprocal Rank Fusion, and reranking in C#.

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Hybrid Search in .NET

A RAG application can have a powerful LLM, a well-configured vector database, and properly generated embeddings, and still retrieve the wrong information.

Consider an internal assistant. A developer asks, "What is the timeout configured for PaymentGatewayClient in version 3.2?" The knowledge base holds a payment gateway integration guide, an API configuration reference, version 3.2 deployment notes, and general HTTP client documentation. A conventional semantic search may return documents about HTTP clients and payment gateways without prioritizing the exact version-specific configuration.

The problem isn't necessarily the LLM. It may exist much earlier, in the retrieval pipeline. That's where hybrid search in .NET and reranking come in.…