index_options parameter controls what information is added to the
inverted index for search and highlighting purposes. Only term-based field
keyword support this
The parameter accepts one of the following values. Each value retrieves
information from the previous listed values. For example,
positions contains both
- 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.