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Elasticsearch Guide [8.1] » Mapping » Mapping parameters » position_increment_gap
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position_increment_gap

Analyzed text fields take term positions into account, in order to be able to support proximity or phrase queries. When indexing text fields with multiple values a "fake" gap is added between the values to prevent most phrase queries from matching across the values. The size of this gap is configured using position_increment_gap and defaults to 100.

For example:

PUT my-index-000001/_doc/1
{
  "names": [ "John Abraham", "Lincoln Smith"]
}

GET my-index-000001/_search
{
  "query": {
    "match_phrase": {
      "names": {
        "query": "Abraham Lincoln" 
      }
    }
  }
}

GET my-index-000001/_search
{
  "query": {
    "match_phrase": {
      "names": {
        "query": "Abraham Lincoln",
        "slop": 101 
      }
    }
  }
}

This phrase query doesn’t match our document which is totally expected.

This phrase query matches our document, even though Abraham and Lincoln are in separate strings, because slop > position_increment_gap.

The position_increment_gap can be specified in the mapping. For instance:

PUT my-index-000001
{
  "mappings": {
    "properties": {
      "names": {
        "type": "text",
        "position_increment_gap": 0 
      }
    }
  }
}

PUT my-index-000001/_doc/1
{
  "names": [ "John Abraham", "Lincoln Smith"]
}

GET my-index-000001/_search
{
  "query": {
    "match_phrase": {
      "names": "Abraham Lincoln" 
    }
  }
}

The first term in the next array element will be 0 terms apart from the last term in the previous array element.

The phrase query matches our document which is weird, but its what we asked for in the mapping.
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