How to Migrate from Keyword to Vector Search on Amazon OpenSearch Service

Organizations relying solely on keyword-based search are increasingly failing users who phrase queries as natural-language questions, a pattern that shows up as abandoned searches, repeated queries, and costly support calls. Keyword search works well for exact product codes or document titles but breaks down when users and content authors use different vocabulary, such as 'vehicle hire' versus 'car rental.' Vector search addresses this by mapping text to semantic coordinates, allowing queries to match by meaning rather than exact character strings. Amazon OpenSearch Service supports both lexical and vector search, enabling teams to run a hybrid approach rather than replacing their existing keyword infrastructure outright. The guide outlines how to identify where keyword search is failing, what vector and hybrid search change for both end users and AI agents, and how to stage a migration without dismantling current systems.