More like this query

More like this query #

more_like_this finds documents similar to given text or documents. The engine extracts the input’s terms, keeps the significant ones, and runs the resulting top terms as a disjunctive query — a “find more of this” query without any embedding model.

fields is required and limited to text fields.

How it works #

The query is rewritten at the search entry point — it is a client of the analysis and term pipeline, not an index structure. Per field: gather the like text (free text is analyzed with the first field’s analyzer; a referenced document contributes the text of every query field), tokenize it, drop terms below min_term_freq, outside the word-length bounds, or listed in stop_words, and remove every term the unlike inputs produced. The surviving terms from all fields are pooled, ranked by source term frequency (ties broken alphabetically for determinism), and the top max_query_terms become a bool.should of term queries governed by minimum_should_match. If nothing survives, the query matches nothing. When include is false (the default) and the like input named documents, their ids are added as a must_not — the seed documents trivially contain every selected term.