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Elasticsearch Guide [6.6] » Analysis » Token Filters » Keyword Marker Token Filter
« Stemmer Override Token Filter Keyword Repeat Token Filter »

Keyword Marker Token Filteredit

Protects words from being modified by stemmers. Must be placed before any stemming filters.

Setting Description

keywords

A list of words to use.

keywords_path

A path (either relative to config location, or absolute) to a list of words.

keywords_pattern

A regular expression pattern to match against words in the text.

ignore_case

Set to true to lower case all words first. Defaults to false.

You can configure it like:

PUT /keyword_marker_example
{
  "settings": {
    "analysis": {
      "analyzer": {
        "protect_cats": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": ["lowercase", "protect_cats", "porter_stem"]
        },
        "normal": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": ["lowercase", "porter_stem"]
        }
      },
      "filter": {
        "protect_cats": {
          "type": "keyword_marker",
          "keywords": ["cats"]
        }
      }
    }
  }
}

And test it with:

POST /keyword_marker_example/_analyze
{
  "analyzer" : "protect_cats",
  "text" : "I like cats"
}

And it’d respond:

{
  "tokens": [
    {
      "token": "i",
      "start_offset": 0,
      "end_offset": 1,
      "type": "<ALPHANUM>",
      "position": 0
    },
    {
      "token": "like",
      "start_offset": 2,
      "end_offset": 6,
      "type": "<ALPHANUM>",
      "position": 1
    },
    {
      "token": "cats",
      "start_offset": 7,
      "end_offset": 11,
      "type": "<ALPHANUM>",
      "position": 2
    }
  ]
}

As compared to the normal analyzer which has cats stemmed to cat:

POST /keyword_marker_example/_analyze
{
  "analyzer" : "normal",
  "text" : "I like cats"
}

Response:

{
  "tokens": [
    {
      "token": "i",
      "start_offset": 0,
      "end_offset": 1,
      "type": "<ALPHANUM>",
      "position": 0
    },
    {
      "token": "like",
      "start_offset": 2,
      "end_offset": 6,
      "type": "<ALPHANUM>",
      "position": 1
    },
    {
      "token": "cat",
      "start_offset": 7,
      "end_offset": 11,
      "type": "<ALPHANUM>",
      "position": 2
    }
  ]
}
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