Hybrid Search

Full-text search finds documents that contain the words of your query. Semantic search finds documents with a similar meaning, even when they use different words. Hybrid search runs both and merges the results into one list.

Hybrid search has two parts:

• HYBRID fields are indexed for both full-text and semantic search.
• Retrievers run the searches. $ann runs a semantic search, and $rrf merges the results of several retrievers into one list.

Hybrid fields#

A HYBRID field is a TEXT field that also stores a vector embedding. Full-text queries work on it the same way as on a TEXT field, and $ann searches its embeddings by meaning. See Hybrid Fields for the field options.

• An index can have more than one HYBRID field.
• If the text of a document cannot be embedded, the document is still searchable by its text.
• HYBRID fields work with JSON, hash, string, and stream indexes.

Create an index#

Declare the fields you want to search by meaning as HYBRID:

SEARCH.CREATE products ON JSON PREFIX 1 product: SCHEMA name TEXT description HYBRID category KEYWORD price F64 FAST

Add documents#

Write documents as usual. Search indexes them and creates their embeddings:

JSON.SET product:1 $ '{"name": "Studio Headphones", "description": "Over-ear headphones with active noise cancelling", "category": "audio", "price": 199}'JSON.SET product:2 $ '{"name": "Travel Earplugs", "description": "Soft foam earplugs that keep airplane cabin sound out", "category": "travel", "price": 9}'JSON.SET product:3 $ '{"name": "Sport Earbuds", "description": "Sweat-proof wireless earbuds for running", "category": "sports", "price": 79}'# Wait until the documents are indexedSEARCH.WAITINDEXING products

Search by meaning#

Use $ann to find the documents that are closest in meaning to a text. This query can find the earplugs, even though their description does not contain the word “noise”:

SEARCH.QUERY products '{"$ann": {"field": "description", "query": "block noise on a flight"}}'# Search by meaning within one categorySEARCH.QUERY products '{"$ann": {"field": "description", "query": "headphones for running", "filter": {"category": "sports"}}}'

Combine full-text and semantic search#

Use $rrf to run a full-text query and a semantic search, and merge their results into one list. Documents that rank high in both come first:

SEARCH.QUERY products '{"$rrf": {"retrievers": [{"description": "noise cancelling"}, {"$ann": {"field": "description", "query": "noise cancelling"}}]}}'

To give one side more influence, set its weight. A full-text query takes a weight when you wrap it in $standard:

SEARCH.QUERY products '{"$rrf": {"retrievers": [{"$standard": {"query": {"description": "noise cancelling"}, "weight": 2}}, {"$ann": {"field": "description", "query": "noise cancelling"}}]}}'

Next steps#

• See Retrievers for all retriever parameters and rules.
• See Schema Definition for field types and options.
• See SEARCH.QUERY for all query options.