Field data types - Text - 《Elasticsearch v7.9 Reference》

Text field type
- Use a field as both text and keyword
- Parameters for text fields

Text field type

A field to index full-text values, such as the body of an email or the description of a product. These fields are analyzed, that is they are passed through an analyzer to convert the string into a list of individual terms before being indexed. The analysis process allows Elasticsearch to search for individual words within each full text field. Text fields are not used for sorting and seldom used for aggregations (although the significant text aggregation is a notable exception).

If you need to index structured content such as email addresses, hostnames, status codes, or tags, it is likely that you should rather use a keyword field.

Below is an example of a mapping for a text field:

PUT my-index-000001
{
  "mappings": {
    "properties": {
      "full_name": {
        "type":  "text"
      }
    }
  }
}

Use a field as both text and keyword

Sometimes it is useful to have both a full text (text) and a keyword (keyword) version of the same field: one for full text search and the other for aggregations and sorting. This can be achieved with multi-fields.

Parameters for text fields

The following parameters are accepted by text fields:

`analyzer`	The analyzer which should be used for the `text` field, both at index-time and at search-time (unless overridden by the `search_analyzer`). Defaults to the default index analyzer, or the `standard` analyzer.
`boost`	Mapping field-level query time boosting. Accepts a floating point number, defaults to `1.0`.
`eager_global_ordinals`	Should global ordinals be loaded eagerly on refresh? Accepts `true` or `false` (default). Enabling this is a good idea on fields that are frequently used for (significant) terms aggregations.
`fielddata`	Can the field use in-memory fielddata for sorting, aggregations, or scripting? Accepts `true` or `false` (default).
`fielddata_frequency_filter`	Expert settings which allow to decide which values to load in memory when `fielddata` is enabled. By default all values are loaded.
`fields`	Multi-fields allow the same string value to be indexed in multiple ways for different purposes, such as one field for search and a multi-field for sorting and aggregations, or the same string value analyzed by different analyzers.
`index`	Should the field be searchable? Accepts `true` (default) or `false`.
`index_options`	What information should be stored in the index, for search and highlighting purposes. Defaults to `positions`.
`index_prefixes`	If enabled, term prefixes of between 2 and 5 characters are indexed into a separate field. This allows prefix searches to run more efficiently, at the expense of a larger index.
`index_phrases`	If enabled, two-term word combinations (shingles) are indexed into a separate field. This allows exact phrase queries (no slop) to run more efficiently, at the expense of a larger index. Note that this works best when stopwords are not removed, as phrases containing stopwords will not use the subsidiary field and will fall back to a standard phrase query. Accepts `true` or `false` (default).
`norms`	Whether field-length should be taken into account when scoring queries. Accepts `true` (default) or `false`.
`position_increment_gap`	The number of fake term position which should be inserted between each element of an array of strings. Defaults to the `position_increment_gap` configured on the analyzer which defaults to `100`. `100` was chosen because it prevents phrase queries with reasonably large slops (less than 100) from matching terms across field values.
`store`	Whether the field value should be stored and retrievable separately from the `_source` field. Accepts `true` or `false` (default).
`search_analyzer`	The `analyzer` that should be used at search time on the `text` field. Defaults to the `analyzer` setting.
`search_quote_analyzer`	The `analyzer` that should be used at search time when a phrase is encountered. Defaults to the `search_analyzer` setting.
`similarity`	Which scoring algorithm or similarity should be used. Defaults to `BM25`.
`term_vector`	Whether term vectors should be stored for the field. Defaults to `no`.
`meta`	Metadata about the field.