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In a few previous PR's we restructured the ES|QL docs to make it possible to generate them dynamically. This PR just moves a few files around to make the query languages docs easier to work with, and a little more organized like the ES|QL docs. A bit part of this was setting up redirects to the new locations, so other repo's could correctly link to the elasticsearch docs.
76 lines
3.7 KiB
Markdown
76 lines
3.7 KiB
Markdown
---
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navigation_title: "Match phrase prefix"
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mapped_pages:
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- https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-match-query-phrase-prefix.html
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---
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# Match phrase prefix query [query-dsl-match-query-phrase-prefix]
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Returns documents that contain the words of a provided text, in the **same order** as provided. The last term of the provided text is treated as a [prefix](/reference/query-languages/query-dsl/query-dsl-prefix-query.md), matching any words that begin with that term.
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## Example request [match-phrase-prefix-query-ex-request]
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The following search returns documents that contain phrases beginning with `quick brown f` in the `message` field.
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This search would match a `message` value of `quick brown fox` or `two quick brown ferrets` but not `the fox is quick and brown`.
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```console
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GET /_search
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{
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"query": {
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"match_phrase_prefix": {
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"message": {
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"query": "quick brown f"
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}
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}
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}
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}
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```
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## Top-level parameters for `match_phrase_prefix` [match-phrase-prefix-top-level-params]
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`<field>`
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: (Required, object) Field you wish to search.
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## Parameters for `<field>` [match-phrase-prefix-field-params]
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`query`
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: (Required, string) Text you wish to find in the provided `<field>`.
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The `match_phrase_prefix` query [analyzes](docs-content://manage-data/data-store/text-analysis.md) any provided text into tokens before performing a search. The last term of this text is treated as a [prefix](/reference/query-languages/query-dsl/query-dsl-prefix-query.md), matching any words that begin with that term.
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`analyzer`
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: (Optional, string) [Analyzer](docs-content://manage-data/data-store/text-analysis.md) used to convert text in the `query` value into tokens. Defaults to the [index-time analyzer](docs-content://manage-data/data-store/text-analysis/specify-an-analyzer.md#specify-index-time-analyzer) mapped for the `<field>`. If no analyzer is mapped, the index’s default analyzer is used.
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`max_expansions`
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: (Optional, integer) Maximum number of terms to which the last provided term of the `query` value will expand. Defaults to `50`.
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`slop`
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: (Optional, integer) Maximum number of positions allowed between matching tokens. Defaults to `0`. Transposed terms have a slop of `2`.
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`zero_terms_query`
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: (Optional, string) Indicates whether no documents are returned if the `analyzer` removes all tokens, such as when using a `stop` filter. Valid values are:
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`none` (Default)
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: No documents are returned if the `analyzer` removes all tokens.
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`all`
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: Returns all documents, similar to a [`match_all`](/reference/query-languages/query-dsl/query-dsl-match-all-query.md) query.
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## Notes [match-phrase-prefix-query-notes]
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### Using the match phrase prefix query for search autocompletion [match-phrase-prefix-autocomplete]
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While easy to set up, using the `match_phrase_prefix` query for search autocompletion can sometimes produce confusing results.
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For example, consider the query string `quick brown f`. This query works by creating a phrase query out of `quick` and `brown` (i.e. the term `quick` must exist and must be followed by the term `brown`). Then it looks at the sorted term dictionary to find the first 50 terms that begin with `f`, and adds these terms to the phrase query.
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The problem is that the first 50 terms may not include the term `fox` so the phrase `quick brown fox` will not be found. This usually isn’t a problem as the user will continue to type more letters until the word they are looking for appears.
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For better solutions for *search-as-you-type* check out the [completion suggester](/reference/elasticsearch/rest-apis/search-suggesters.md#completion-suggester) and the [`search_as_you_type` field type](/reference/elasticsearch/mapping-reference/search-as-you-type.md).
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