70 lines
1.9 KiB
Markdown
70 lines
1.9 KiB
Markdown
---
|
|
layout: default
|
|
title: Prefix
|
|
parent: Term-level queries
|
|
grand_parent: Query DSL
|
|
nav_order: 40
|
|
---
|
|
|
|
# Prefix query
|
|
|
|
Use the `prefix` query to search for terms that begin with a specific prefix. For example, the following query searches for documents in which the `speaker` field contains a term that starts with `KING H`:
|
|
|
|
```json
|
|
GET shakespeare/_search
|
|
{
|
|
"query": {
|
|
"prefix": {
|
|
"speaker": "KING H"
|
|
}
|
|
}
|
|
}
|
|
```
|
|
{% include copy-curl.html %}
|
|
|
|
To provide parameters, you can use a query equivalent to the preceding one with the following extended syntax:
|
|
|
|
```json
|
|
GET shakespeare/_search
|
|
{
|
|
"query": {
|
|
"prefix": {
|
|
"speaker": {
|
|
"value": "KING H"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
{% include copy-curl.html %}
|
|
|
|
|
|
## Parameters
|
|
|
|
The query accepts the name of the field (`<field>`) as a top-level parameter:
|
|
|
|
```json
|
|
GET _search
|
|
{
|
|
"query": {
|
|
"prefix": {
|
|
"<field>": {
|
|
"value": "sample",
|
|
...
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
{% include copy-curl.html %}
|
|
|
|
The `<field>` accepts the following parameters. All parameters except `value` are optional.
|
|
|
|
Parameter | Data type | Description
|
|
:--- | :--- | :---
|
|
`value` | String | The term to search for in the field specified in `<field>`.
|
|
`case_insensitive` | Boolean | If `true`, allows case-insensitive matching of the value with the indexed field values. Default is `false` (case sensitivity is determined by the field's mapping).
|
|
`rewrite` | String | Determines how OpenSearch rewrites and scores multi-term queries. Valid values are `constant_score`, `scoring_boolean`, `constant_score_boolean`, `top_terms_N`, `top_terms_boost_N`, and `top_terms_blended_freqs_N`. Default is `constant_score`.
|
|
|
|
If [`search.allow_expensive_queries`]({{site.url}}{{site.baseurl}}/query-dsl/index/#expensive-queries) is set to `false`, prefix queries are not run. If `index_prefixes` is enabled, the `search.allow_expensive_queries` setting is ignored and an optimized query is built and run.
|
|
{: .important} |