Elasticsearch “pattern_replace”, replacing whitespaces while analyzing

Question

Basically I want to remove all whitespaces and tokenize the whole string as a single token. (I will use nGram on top of that later on.)

This is my index settings:

"settings": {
 "index": {
  "analysis": {
    "filter": {
      "whitespace_remove": {
        "type": "pattern_replace",
        "pattern": " ",
        "replacement": ""
      }
    },
    "analyzer": {
      "meliuz_analyzer": {
        "filter": [
          "lowercase",
          "whitespace_remove"
        ],
        "type": "custom",
        "tokenizer": "standard"
      }
    }
  }
}

Instead of "pattern": " ", I tried "pattern": "\\u0020" and \\s , too.

But when I analyze the text "beleza na web", it still creates three separate tokens: "beleza", "na" and "web", instead of one single "belezanaweb".

Answer 1

The analyzer analyzes a string by tokenizing it first then applying a series of token filters. You have specified tokenizer as standard means the input is already tokenized using standard tokenizer which created the tokens separately. Then pattern replace filter is applied to the tokens.

Use keyword tokenizer instead of your standard tokenizer. Rest of the mapping is fine. You can change your mapping as below

"settings": {
 "index": {
  "analysis": {
    "filter": {
      "whitespace_remove": {
        "type": "pattern_replace",
        "pattern": " ",
        "replacement": ""
      }
    },
    "analyzer": {
      "meliuz_analyzer": {
        "filter": [
          "lowercase",
          "whitespace_remove",
          "nGram"
        ],
        "type": "custom",
        "tokenizer": "keyword"
      }
    }
  }
}