This functionality is experimental and may be changed or removed completely in a future release. Elastic will take a best effort approach to fix any issues, but experimental features are not subject to the support SLA of official GA features.

A dense_vector field stores dense vectors of float values. The maximum number of dimensions that can be in a vector should not exceed 500. The number of dimensions can be different across documents. A dense_vector field is a single-valued field.

These vectors can be used for document scoring. For example, a document score can represent a distance between a given query vector and the indexed document vector.

You index a dense vector as an array of floats.

PUT my_index
{
  "mappings": {
    "properties": {
      "my_vector": {
        "type": "dense_vector"
      },
      "my_text" : {
        "type" : "keyword"
      }
    }
  }
}

PUT my_index/_doc/1
{
  "my_text" : "text1",
  "my_vector" : [0.5, 10, 6]
}

PUT my_index/_doc/2
{
  "my_text" : "text2",
  "my_vector" : [-0.5, 10, 10, 4]
}

Internally, each document’s dense vector is encoded as a binary doc value. Its size in bytes is equal to 4 * NUMBER_OF_DIMENSIONS, where NUMBER_OF_DIMENSIONS - number of the vector’s dimensions.