188 lines
6.2 KiB
Plaintext
188 lines
6.2 KiB
Plaintext
[[query-dsl-match-query]]
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=== Match query
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++++
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<titleabbrev>Match</titleabbrev>
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++++
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`match` queries accept text/numerics/dates, analyzes
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them, and constructs a query. For example:
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query": {
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"match" : {
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"message" : "this is a test"
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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Note, `message` is the name of a field, you can substitute the name of
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any field instead.
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[[query-dsl-match-query-boolean]]
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==== match
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The `match` query is of type `boolean`. It means that the text
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provided is analyzed and the analysis process constructs a boolean query
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from the provided text. The `operator` flag can be set to `or` or `and`
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to control the boolean clauses (defaults to `or`). The minimum number of
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optional `should` clauses to match can be set using the
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<<query-dsl-minimum-should-match,`minimum_should_match`>>
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parameter.
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The `analyzer` can be set to control which analyzer will perform the
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analysis process on the text. It defaults to the field explicit mapping
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definition, or the default search analyzer.
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The `lenient` parameter can be set to `true` to ignore exceptions caused by
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data-type mismatches, such as trying to query a numeric field with a text
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query string. Defaults to `false`.
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[[query-dsl-match-query-fuzziness]]
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===== Fuzziness
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`fuzziness` allows _fuzzy matching_ based on the type of field being queried.
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See <<fuzziness>> for allowed settings.
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The `prefix_length` and
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`max_expansions` can be set in this case to control the fuzzy process.
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If the fuzzy option is set the query will use `top_terms_blended_freqs_${max_expansions}`
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as its <<query-dsl-multi-term-rewrite,rewrite
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method>> the `fuzzy_rewrite` parameter allows to control how the query will get
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rewritten.
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Fuzzy transpositions (`ab` -> `ba`) are allowed by default but can be disabled
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by setting `fuzzy_transpositions` to `false`.
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NOTE: Fuzzy matching is not applied to terms with synonyms or in cases where the
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analysis process produces multiple tokens at the same position. Under the hood
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these terms are expanded to a special synonym query that blends term frequencies,
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which does not support fuzzy expansion.
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query": {
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"match" : {
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"message" : {
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"query" : "this is a test",
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"operator" : "and"
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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[[query-dsl-match-query-zero]]
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===== Zero terms query
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If the analyzer used removes all tokens in a query like a `stop` filter
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does, the default behavior is to match no documents at all. In order to
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change that the `zero_terms_query` option can be used, which accepts
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`none` (default) and `all` which corresponds to a `match_all` query.
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query": {
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"match" : {
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"message" : {
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"query" : "to be or not to be",
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"operator" : "and",
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"zero_terms_query": "all"
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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[[query-dsl-match-query-cutoff]]
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===== Cutoff frequency
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deprecated[7.3.0,"This option can be omitted as the <<query-dsl-match-query>> can skip block of documents efficiently, without any configuration, provided that the total number of hits is not tracked."]
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The match query supports a `cutoff_frequency` that allows
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specifying an absolute or relative document frequency where high
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frequency terms are moved into an optional subquery and are only scored
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if one of the low frequency (below the cutoff) terms in the case of an
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`or` operator or all of the low frequency terms in the case of an `and`
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operator match.
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This query allows handling `stopwords` dynamically at runtime, is domain
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independent and doesn't require a stopword file. It prevents scoring /
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iterating high frequency terms and only takes the terms into account if a
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more significant / lower frequency term matches a document. Yet, if all
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of the query terms are above the given `cutoff_frequency` the query is
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automatically transformed into a pure conjunction (`and`) query to
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ensure fast execution.
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The `cutoff_frequency` can either be relative to the total number of
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documents if in the range `[0..1)` or absolute if greater or equal to
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`1.0`.
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Here is an example showing a query composed of stopwords exclusively:
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query": {
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"match" : {
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"message" : {
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"query" : "to be or not to be",
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"cutoff_frequency" : 0.001
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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// TEST[warning:Deprecated field [cutoff_frequency] used, replaced by [you can omit this option, the [match] query can skip block of documents efficiently if the total number of hits is not tracked]]
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IMPORTANT: The `cutoff_frequency` option operates on a per-shard-level. This means
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that when trying it out on test indexes with low document numbers you
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should follow the advice in {defguide}/relevance-is-broken.html[Relevance is broken].
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[[query-dsl-match-query-synonyms]]
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===== Synonyms
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The `match` query supports multi-terms synonym expansion with the <<analysis-synonym-graph-tokenfilter,
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synonym_graph>> token filter. When this filter is used, the parser creates a phrase query for each multi-terms synonyms.
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For example, the following synonym: `"ny, new york" would produce:`
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`(ny OR ("new york"))`
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It is also possible to match multi terms synonyms with conjunctions instead:
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query": {
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"match" : {
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"message": {
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"query" : "ny city",
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"auto_generate_synonyms_phrase_query" : false
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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The example above creates a boolean query:
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`(ny OR (new AND york)) city`
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that matches documents with the term `ny` or the conjunction `new AND york`.
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By default the parameter `auto_generate_synonyms_phrase_query` is set to `true`.
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