Redis®*: Querying

This documentation is part of the Vector search and RAG guide. You can view the complete guide here: Semantic search, recommendations, and retrieval-augmented generation with Redis.

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A K nearest neighbors (KNN) query is written as follows. The vector is provided as raw little-endian float32 bytes:

FT.SEARCH chunksIndex "*=>[KNN 5 @embedding $queryVector AS score]"
  PARAMS 2 queryVector "<rawBytes>"
  SORTBY score
  RETURN 2 content score
  DIALECT 2

To combine similarity search with filters, simply replace * with a filter expression:

FT.SEARCH chunksIndex "(@documentId:{doc42} @publishedAt:[1735689600 +inf])=>[KNN 5 @embedding $queryVector AS score]"
  PARAMS 2 queryVector "<rawBytes>"
  SORTBY score
  DIALECT 2

Vector queries require DIALECT 2. If you omit this, the query uses the older syntax and returns an error.