elasticsearch/docs/reference/mapping/params/index-phrases.asciidoc

[[index-phrases]]
=== `index_phrases`

If enabled, two-term word combinations ('shingles') are indexed into a separate
field.  This allows exact phrase queries (no slop) to run more efficiently, at the expense
of a larger index.  Note that this works best when stopwords are not removed,
as phrases containing stopwords will not use the subsidiary field and will fall
back to a standard phrase query.  Accepts `true` or `false` (default).