﻿---
title: Completion field type
description: To use the completion suggester, map the field from which you want to generate suggestions as type completion. This indexes the field values for fast...
url: https://www.elastic.co/elastic/docs-builder/docs/2848/reference/elasticsearch/mapping-reference/completion
products:
  - Elasticsearch
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available
---

# Completion field type
To use the `completion` suggester, map the field from which you want to generate suggestions as type `completion`. This indexes the field values for fast completions.
```json

{
  "mappings": {
    "properties": {
      "suggest": {
        "type": "completion"
      }
    }
  }
}
```


## Parameters for `completion` fields

The following parameters are accepted by `completion` fields:
<definitions>
  <definition term="analyzer">
    The index analyzer to use, defaults to `simple`.
  </definition>
  <definition term="search_analyzer">
    The search analyzer to use, defaults to value of `analyzer`.
  </definition>
  <definition term="preserve_separators">
    Preserves the separators, defaults to `true`. If disabled, you could find a field starting with `Foo Fighters`, if you suggest for `foof`.
  </definition>
  <definition term="preserve_position_increments">
    Enables position increments, defaults to `true`. If disabled and using stopwords analyzer, you could get a field starting with `The Beatles`, if you suggest for `b`. **Note**: You could also achieve this by indexing two inputs, `Beatles` and `The Beatles`, no need to change a simple analyzer, if you are able to enrich your data.
  </definition>
  <definition term="max_input_length">
    Limits the length of a single input, defaults to `50` UTF-16 code points. This limit is only used at index time to reduce the total number of characters per input string in order to prevent massive inputs from bloating the underlying datastructure. Most use cases won’t be influenced by the default value since prefix completions seldom grow beyond prefixes longer than a handful of characters.
  </definition>
</definitions>

For more information about completion suggesters, refer to [Suggester examples](https://www.elastic.co/elastic/docs-builder/docs/2848/reference/elasticsearch/rest-apis/search-suggesters).