A support question can contain an exact error code and an informal description of a symptom. Keyword search is useful for the code; semantic search can find a differently worded explanation. Combining the candidate lists can cover both needs.
The implementation must decide how to merge rankings or scores, deduplicate results, and apply filters. A weight favoring one retrieval path is a tuning choice, rather than a universal recipe. Compare performance on queries with identifiers as well as queries that require paraphrase matching.
Example: if an error-code question returns a generic troubleshooting article ahead of the specific fix, inspect the fusion and filters before replacing the answer model. A larger answer model does not repair that missing retrieval evidence.
Hybrid search selects candidates from multiple retrieval paths. Reranking scores an already retrieved candidate set more closely; it can follow hybrid retrieval. RAG then supplies selected evidence to a model that writes an answer. Test retrieval quality separately from the quality of that answer.
Sources
- Weaviate: Hybrid search — Describes keyword/vector retrieval and result fusion.
