index_options

The index_options parameter controls what information is added to the inverted index for search and highlighting purposes. Only term-based field types like text and keyword support this configuration.

Note

The semantic_text field type also uses an index_options parameter. However, in that context, the parameter configures the underlying vector index settings (such as quantization or token pruning) rather than standard text indexing features. See the semantic text documentation to configure index_options for sparse vectors or dense vectors.

The parameter accepts one of the following values. Each value retrieves information from the previous listed values. For example, freqs contains docs; positions contains both freqs and docs.

docs: Only the doc number is indexed. Can answer the question Does this term exist in this field?
freqs: Doc number and term frequencies are indexed. Term frequencies are used to score repeated terms higher than single terms.
positions (default): Doc number, term frequencies, and term positions (or order) are indexed. Positions can be used for proximity or phrase queries.
offsets: Doc number, term frequencies, positions, and start and end character offsets (which map the term back to the original string) are indexed. Offsets are used by the unified highlighter to speed up highlighting.

PUT my-index-000001
{
  "mappings": {
    "properties": {
      "text": {
        "type": "text",
        "index_options": "offsets"
      }
    }
  }
}
PUT my-index-000001/_doc/1
{
  "text": "Quick brown fox"
}
GET my-index-000001/_search
{
  "query": {
    "match": {
      "text": "brown fox"
    }
  },
  "highlight": {
    "fields": {
      "text": {}
    }
  }
}

The text field will use the postings for the highlighting by default because offsets are indexed.