rewrite parameter
editrewrite
parameter
editThis parameter is for expert users only. Changing the value of this parameter can impact search performance and relevance.
Elasticsearch uses Apache Lucene internally to power indexing and searching. In their original form, Lucene cannot execute the following queries:
To execute them, Lucene changes these queries to a simpler form, such as a
bool
query or a
bit set.
The rewrite
parameter determines:
- How Lucene calculates the relevance scores for each matching document
-
Whether Lucene changes the original query to a
bool
query or bit set -
If changed to a
bool
query, whichterm
query clauses are included
Valid values
edit-
constant_score
(Default) -
Uses the
constant_score_boolean
method for fewer matching terms. Otherwise, this method finds all matching terms in sequence and returns matching documents using a bit set. -
constant_score_boolean
-
Assigns each document a relevance score equal to the
boost
parameter.This method changes the original query to a
bool
query. Thisbool
query contains ashould
clause andterm
query for each matching term.This method can cause the final
bool
query to exceed the clause limit in theindices.query.bool.max_clause_count
setting. If the query exceeds this limit, Elasticsearch returns an error. -
scoring_boolean
-
Calculates a relevance score for each matching document.
This method changes the original query to a
bool
query. Thisbool
query contains ashould
clause andterm
query for each matching term.This method can cause the final
bool
query to exceed the clause limit in theindices.query.bool.max_clause_count
setting. If the query exceeds this limit, Elasticsearch returns an error. -
top_terms_blended_freqs_N
-
Calculates a relevance score for each matching document as if all terms had the same frequency. This frequency is the maximum frequency of all matching terms.
This method changes the original query to a
bool
query. Thisbool
query contains ashould
clause andterm
query for each matching term.The final
bool
query only includesterm
queries for the topN
scoring terms.You can use this method to avoid exceeding the clause limit in the
indices.query.bool.max_clause_count
setting. -
top_terms_boost_N
-
Assigns each matching document a relevance score equal to the
boost
parameter.This method changes the original query to a
bool
query. Thisbool
query contains ashould
clause andterm
query for each matching term.The final
bool
query only includesterm
queries for the topN
terms.You can use this method to avoid exceeding the clause limit in the
indices.query.bool.max_clause_count
setting. -
top_terms_N
-
Calculates a relevance score for each matching document.
This method changes the original query to a
bool
query. Thisbool
query contains ashould
clause andterm
query for each matching term.The final
bool
query only includesterm
queries for the topN
scoring terms.You can use this method to avoid exceeding the clause limit in the
indices.query.bool.max_clause_count
setting.
Performance considerations for the rewrite
parameter
editFor most uses, we recommend using the constant_score
,
constant_score_boolean
, or top_terms_boost_N
rewrite methods.
Other methods calculate relevance scores. These score calculations are often expensive and do not improve query results.