How does a multi-match query work in Elasticsearch?

When a multi-match query is executed in Elasticsearch, it searches for documents that contain one or more search terms in one or more specified fields. The multi-match query constructs a query that searches for the term in all specified fields and returns any documents that contain a matching term in any of the specified fields.

Here’s an example of a multi-match query in Elasticsearch:

GET /my_index/_search
{
  "query": {
    "multi_match": {
      "query": "elasticsearch",
      "fields": ["title", "description"]
    }
  }
}

In this example, we are searching the `title` and `description` fields in the `my_index` index for documents that contain the term “elasticsearch”. The multi-match query constructs a query that searches for the term in both the `title` and `description` fields.

The multi-match query also supports a variety of other features, such as specifying different levels of importance or weighting for different fields, using fuzzy matching or wildcard matching, and specifying minimum and maximum should match parameters.

The multi-match query can also be used in combination with other query types, such as the bool query, to construct more complex search queries. By allowing for searching across multiple fields with the same query, the multi-match query provides a powerful and flexible way to search for text in Elasticsearch.

However, it’s important to note that multi-match queries can be computationally expensive and may not be suitable for large datasets or high-traffic applications. Additionally, multi-match queries can be less precise than other query types, such as the term or match query, because they match a broader range of terms. Therefore, it’s important to carefully consider the use case and performance implications before using multi-match queries in Elasticsearch.