165 lines
5.6 KiB
Plaintext
165 lines
5.6 KiB
Plaintext
[[query-dsl-query-string-query]]
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=== Query String Query
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A query that uses a query parser in order to parse its content. Here is
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an example:
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[source,js]
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--------------------------------------------------
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{
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"query_string" : {
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"default_field" : "content",
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"query" : "this AND that OR thus"
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}
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}
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--------------------------------------------------
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The `query_string` top level parameters include:
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[cols="<,<",options="header",]
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|=======================================================================
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|Parameter |Description
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|`query` |The actual query to be parsed. See <<query-string-syntax>>.
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|`default_field` |The default field for query terms if no prefix field
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is specified. Defaults to the `index.query.default_field` index
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settings, which in turn defaults to `_all`.
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|`default_operator` |The default operator used if no explicit operator
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is specified. For example, with a default operator of `OR`, the query
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`capital of Hungary` is translated to `capital OR of OR Hungary`, and
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with default operator of `AND`, the same query is translated to
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`capital AND of AND Hungary`. The default value is `OR`.
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|`analyzer` |The analyzer name used to analyze the query string.
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|`allow_leading_wildcard` |When set, `*` or `?` are allowed as the first
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character. Defaults to `true`.
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|`lowercase_expanded_terms` |Whether terms of wildcard, prefix, fuzzy,
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and range queries are to be automatically lower-cased or not (since they
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are not analyzed). Default it `true`.
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|`enable_position_increments` |Set to `true` to enable position
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increments in result queries. Defaults to `true`.
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|`fuzzy_max_expansions` |Controls the number of terms fuzzy queries will
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expand to. Defaults to `50`
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|`fuzziness` |Set the fuzziness for fuzzy queries. Defaults
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to `AUTO`. See <<fuzziness>> for allowed settings.
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|`fuzzy_prefix_length` |Set the prefix length for fuzzy queries. Default
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is `0`.
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|`phrase_slop` |Sets the default slop for phrases. If zero, then exact
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phrase matches are required. Default value is `0`.
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|`boost` |Sets the boost value of the query. Defaults to `1.0`.
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|`analyze_wildcard` |By default, wildcards terms in a query string are
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not analyzed. By setting this value to `true`, a best effort will be
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made to analyze those as well.
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|`auto_generate_phrase_queries` |Default to `false`.
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|`minimum_should_match` |A value controlling how many "should" clauses
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in the resulting boolean query should match. It can be an absolute value
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(`2`), a percentage (`30%`) or a
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<<query-dsl-minimum-should-match,combination of
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both>>.
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|`lenient` |If set to `true` will cause format based failures (like
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providing text to a numeric field) to be ignored.
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|`locale` | coming[1.1.0] Locale that should be used for string conversions.
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Defaults to `ROOT`.
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|=======================================================================
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When a multi term query is being generated, one can control how it gets
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rewritten using the
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<<query-dsl-multi-term-rewrite,rewrite>>
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parameter.
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[float]
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==== Default Field
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When not explicitly specifying the field to search on in the query
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string syntax, the `index.query.default_field` will be used to derive
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which field to search on. It defaults to `_all` field.
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So, if `_all` field is disabled, it might make sense to change it to set
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a different default field.
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[float]
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==== Multi Field
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The `query_string` query can also run against multiple fields. The idea
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of running the `query_string` query against multiple fields is by
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internally creating several queries for the same query string, each with
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`default_field` that match the fields provided. Since several queries
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are generated, combining them can be automatically done either using a
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`dis_max` query or a simple `bool` query. For example (the `name` is
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boosted by 5 using `^5` notation):
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[source,js]
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--------------------------------------------------
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{
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"query_string" : {
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"fields" : ["content", "name^5"],
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"query" : "this AND that OR thus",
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"use_dis_max" : true
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}
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}
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--------------------------------------------------
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Simple wildcard can also be used to search "within" specific inner
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elements of the document. For example, if we have a `city` object with
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several fields (or inner object with fields) in it, we can automatically
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search on all "city" fields:
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[source,js]
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--------------------------------------------------
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{
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"query_string" : {
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"fields" : ["city.*"],
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"query" : "this AND that OR thus",
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"use_dis_max" : true
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}
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}
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--------------------------------------------------
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Another option is to provide the wildcard fields search in the query
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string itself (properly escaping the `*` sign), for example:
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`city.\*:something`.
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When running the `query_string` query against multiple fields, the
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following additional parameters are allowed:
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[cols="<,<",options="header",]
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|=======================================================================
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|Parameter |Description
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|`use_dis_max` |Should the queries be combined using `dis_max` (set it
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to `true`), or a `bool` query (set it to `false`). Defaults to `true`.
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|`tie_breaker` |When using `dis_max`, the disjunction max tie breaker.
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Defaults to `0`.
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|=======================================================================
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The fields parameter can also include pattern based field names,
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allowing to automatically expand to the relevant fields (dynamically
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introduced fields included). For example:
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[source,js]
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--------------------------------------------------
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{
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"query_string" : {
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"fields" : ["content", "name.*^5"],
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"query" : "this AND that OR thus",
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"use_dis_max" : true
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}
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}
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--------------------------------------------------
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include::query-string-syntax.asciidoc[]
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