Query DSL | Elasticsearch Guide [8.5] | Elastic
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Elasticsearch Guide [8.5]
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Query DSLedit
Elasticsearch provides a full Query DSL (Domain Specific Language) based on JSON to define queries.
Think of the Query DSL as an AST (Abstract Syntax Tree) of queries, consisting of two types of
clauses:
Leaf query clauses
Leaf query clauses look for a particular value in a particular field, such as the
match, term or
range queries. These queries can be used
by themselves.
Compound query clauses
Compound query clauses wrap other leaf or compound queries and are used to combine
multiple queries in a logical fashion (such as the
bool or dis_max query),
or to alter their behaviour (such as the
constant_score query).
Query clauses behave differently depending on whether they are used in
query context or filter context.
Allow expensive queries
Certain types of queries will generally execute slowly due to the way they are implemented, which can affect
the stability of the cluster. Those queries can be categorised as follows:
Queries that need to do linear scans to identify matches:
script queries
queries on numeric, date, boolean, ip,
geo_point or keyword fields
that are not indexed but have doc values enabled
Queries that have a high up-front cost:
fuzzy queries (except on
wildcard fields)
regexp queries (except on
wildcard fields)
prefix queries (except on
wildcard fields or those without
index_prefixes)
wildcard queries (except on
wildcard fields)
range queries on text and
keyword fields
Joining queries
Queries that may have a high per-document cost:
script_score queries
percolate queries
The execution of such queries can be prevented by setting the value of the search.allow_expensive_queries
setting to false (defaults to true).
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