Hybrid search in AI Search

  • Release version: Zurich
  • Updated May 6, 2026
  • 3 minutes to read
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    Summary of Hybrid search in AI Search

    Hybrid search in AI Search, introduced in the ServiceNow Otto for AI Search 15 release, combines traditional keyword search with semantic vector search to enhance search accuracy and relevance. Keyword search matches exact terms, while semantic vector search interprets the meaning and context of queries to find results with similar intent. Hybrid search uses Reciprocal Rank Fusion (RRF) to blend these two relevance scores into a single ranking, delivering more precise and contextually relevant results.

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    This mode applies to indexed sources included in the semantic index by default, such as Knowledge Table, Catalog Item Table, Skills, and all External Content Connectors. Additional sources can be manually configured for inclusion.

    Benefits

    • Improved search quality and recall: Combines keyword and semantic matching to retrieve relevant results even when users phrase queries differently.
    • More relevant top-ranked results: Understands user intent beyond keyword matching, improving result relevance.
    • Reduces zero-result searches: Returns useful results for vague or misspelled queries by understanding semantic meaning.

    Availability and Activation

    Hybrid search requires the ServiceNow Otto for AI Search application, available starting with version 15. New installations of this version enable hybrid search automatically for configurations using AI Search as their engine. Legacy Zing-based search configurations do not support hybrid search.

    For upgrades from earlier versions, hybrid search must be manually activated via the AI Search Admin console.

    Interactions and Considerations

    • Activating hybrid search disables search result counts for facets within the configured search application.
    • The "Most recent" sort option changes behavior: AI Search merges keyword and semantic results before sorting by modification date, rather than sorting the entire set after retrieval.

    Practical Use for ServiceNow Customers

    Enabling hybrid search improves the precision and contextual relevance of searches across knowledge articles, catalog items, external content, and topics. Customers can expect enhanced user search experiences, fewer zero-result queries, and better handling of natural language inputs. To leverage these benefits, ensure the ServiceNow Otto for AI Search 15 application is installed and properly configured, and activate hybrid search where appropriate.

    In hybrid search mode, AI Search blends keyword search and semantic vector search to find results that best match the terms and meaning of your search.

    Overview of hybrid search

    In older releases, AI Search performs all searches in keyword search mode. This mode looks for the best matches for your search terms, but doesn't take the context or meaning of those terms into account. The keyword search relevance score for a search result indicates how well the indexed terms in that search result match your search terms.

    AI Search includes an alternate semantic vector search mode in features which work with the Now LLM Service. Semantic vector search analyzes the meanings and context of your search terms and uses that information to find results with similar meanings. It improves search recall by interpreting natural language to more accurately reflect your search's intent. The semantic vector search relevance score for a search result indicates how closely the search result matches the meaning of your search.
    Note:
    To learn more about semantic vector search mode and how it differs from keyword search mode, see Semantic vector search in AI Search.

    Beginning with ServiceNow Otto for AI Search 15, installation of ServiceNow Otto for AI Search offers a new hybrid search mode. This mode combines keyword relevance scores and semantic similarity scores into a single result ranking using Reciprocal Rank Fusion (RRF). By blending keyword and semantic vector search modes, AI Search offers the best of both worlds, providing users with both search precision and contextual relevance.

    Note:
    Hybrid search applies to any indexed source that's included in the semantic index. By default, the following indexed sources ship with preconfigured semantic indexing and work with hybrid search:
    • Knowledge Table indexed source [kb_knowledge table]
    • Catalog Item Table indexed source [sc_cat_item table]
    • Skills indexed source [sys_gen_ai_skill table]
    • All External Content Connectors indexed sources [connector-specific tables]

    You can manually configure additional indexed sources to be included in the semantic index, extending hybrid search to those sources as well.

    To learn more about semantic vector search mode and how it differs from keyword search mode, see Semantic vector search in AI Search.

    Benefits of hybrid search

    Hybrid search offers these benefits when compared with keyword search.
    Improved search quality and recall
    Hybrid search combines keyword and semantic matching, increasing the chances of retrieving relevant results, even when users phrase their queries differently.
    More relevant top-ranked search results
    Understanding the intent of your search, along with matching the words you use, helps find results that match what you mean.
    Fewer zero-result searches
    Hybrid search can return useful results even for vague or misspelled queries because it uses semantic matching to understand meaning beyond exact keywords. This reduces the number of searches that return no results.

    Availability of hybrid search

    Hybrid search requires installation of the ServiceNow Otto for AI Search application. This feature is available beginning in ServiceNow Otto for AI Search 15.

    If you install ServiceNow Otto for AI Search without having any previous version installed, hybrid search is automatically activated for your search application configurations that use AI Search as their search engine.
    Note:
    Search application configurations that use the legacy Zing text indexing and search engine don't support hybrid search.

    If you upgrade to ServiceNow Otto for AI Search from a previous version, hybrid search isn't automatically activated for your search application configurations that use AI Search as their search engine. To learn how to manually activate hybrid search for these search application configurations in the AI Search Admin console, see Manage hybrid search in search applications.

    Interactions with other features

    Activating hybrid search in a search application configuration disables search result counts for facets in that search application configuration. For more information on search result counts for facets, see Show search result counts for facets on the results page for a search application.

    When you activate hybrid search in a search application configuration, the behavior of the Most recent search result sort option changes for the specified search application. Instead of sorting the entire list of search results by last modification date, AI Search first retrieves keyword search results and the most relevant semantic vector search results, then merges those results and sorts them by last modification date. To learn about sorting search results based on recency, see Change the sort order for your search results.