Query and filter context
editQuery and filter context
editThe behaviour of a query clause depends on whether it is used in query context or in filter context:
- Query context
-
A query clause used in query context answers the question “How well does this document match this query clause?” Besides deciding whether or not the document matches, the query clause also calculates a
_score
representing how well the document matches, relative to other documents.Query context is in effect whenever a query clause is passed to a
query
parameter, such as thequery
parameter in thesearch
API. - Filter context
-
In filter context, a query clause answers the question “Does this document match this query clause?” The answer is a simple Yes or No — no scores are calculated. Filter context is mostly used for filtering structured data, e.g.
-
Does this
timestamp
fall into the range 2015 to 2016? -
Is the
status
field set to"published"
?
Frequently used filters will be cached automatically by Elasticsearch, to speed up performance.
Filter context is in effect whenever a query clause is passed to a
filter
parameter, such as thefilter
ormust_not
parameters in thebool
query, thefilter
parameter in theconstant_score
query, or thefilter
aggregation. -
Does this
Below is an example of query clauses being used in query and filter context
in the search
API. This query will match documents where all of the following
conditions are met:
-
The
title
field contains the wordsearch
. -
The
content
field contains the wordelasticsearch
. -
The
status
field contains the exact wordpublished
. -
The
publish_date
field contains a date from 1 Jan 2015 onwards.
GET /_search { "query": { "bool": { "must": [ { "match": { "title": "Search" }}, { "match": { "content": "Elasticsearch" }} ], "filter": [ { "term": { "status": "published" }}, { "range": { "publish_date": { "gte": "2015-01-01" }}} ] } } }
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Use query clauses in query context for conditions which should affect the score of matching documents (i.e. how well does the document match), and use all other query clauses in filter context.