Skip to main content

Partial Matching

Updated Dec 30, 2022 ·

Overview​

Partial matching allows you to search for documents that partially match a given value. This is useful when you want to match substrings or patterns within a field using techniques like prefix or wildcard.

  • prefix matches terms that start with a specified string.
  • wildcard for flexible pattern matching, including the use of * and ?.

Prefix​

Prefix matching is used to search for documents that have a field value starting with a given prefix. It is particularly useful for autocomplete or searching for documents based on the beginning of a string.

  • Prefix queries are faster when the prefix is short.
  • Can be used with keyword or text fields.

Consider an index containing films with different genres. We can use the prefix query to match films with a specific prefix in the year field.

info

Store the Elasticsearch endpoint and credentials in variables:

ELASTIC_ENDPOINT="https://your-elasticsearch-endpoint"
ELASTIC_USER="your-username"
ELASTIC_PW="your-password"
curl -s -u $ELASTIC_USER:$ELASTIC_PW \
-H 'Content-Type: application/json' \
-XGET "$ELASTIC_ENDPOINT:9200/movies/_search?pretty" -d '
{
  "query": {
    "prefix": {
      "year": "201"
    }
  }
}' | jq

This will retrieve all movies where the year field starts with 201, covering years 2010 to 2019.

Wildcard​

Wildcard queries allow for more flexible pattern matching using * (matches any character sequence) and ? (matches a single character). This allows you to find documents with more complex patterns.

  • Wildcards are more flexible but can be slower for large datasets.
  • Can be used to match parts of words or phrases.

Using the previous example, we can use the wildcard query to match movies from years that start with 2.

curl -s -u $ELASTIC_USER:$ELASTIC_PW \
-H 'Content-Type: application/json' \
-XGET "$ELASTIC_ENDPOINT:9200/movies/_search?pretty" -d '
{
  "query": {
    "wildcard": {
      "year": "2*"
    }
  }
}' | jq

This query will retrieve all movies where the year field starts with 2, matching any year in the 2000s.