index_options parameter controls what information is added to the
inverted index for search and highlighting purposes.
index_options parameter is intended for use with
only. Avoid using
index_options with other field data types.
It accepts the following values:
- Only the doc number is indexed. Can answer the question Does this term exist in this field?
- Doc number and term frequencies are indexed. Term frequencies are used to score repeated terms higher than single terms.
- Doc number, term frequencies, and term positions (or order) are indexed. Positions can be used for proximity or phrase queries.
- 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.