Vector vs keyword search: compare retrieval signals

Understand the signals

Keyword search is useful when specific terms, identifiers or quoted phrases matter. Vector search compares representations intended to capture aspects of similarity. It can surface related wording, but similarity does not establish factual relevance or permission to use a document.

Build a realistic test set

Include exact product codes, paraphrased questions, ambiguous names and queries with no valid answer. Judge retrieved passages before judging the generated response. This separates a missing-evidence problem from a model’s failure to use evidence it already received.

Consider a combined approach

A hybrid system can combine lexical and semantic candidates, then rank them for the task. That adds configuration and evaluation work. Keep the simplest approach that retrieves useful evidence reliably, and preserve document permissions throughout the search pipeline.

Sources & notes

An editorial decision framework, not a scored benchmark or hands-on test.

arxiv.org — research paper

Sources reviewed for the September 2026 launch edition.