Elasticsearch wildcard case-sensitive

Question

How to make wildcard case-insensitive?

https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-wildcard-query.html

Answer 1

Since version 7.10 the wildcard query supports special parameter case_insensitive (boolean). Example of case-insensitive search:

GET /_search
{
  "query": {
    "wildcard": {
      "my_field": {
        "value": "ki*y",
        "case_insensitive": true
      }
    }
  }
}

Answer 2

Wildcards are not_analyzed. It depends on what analyzers you've provided for the field you're searching. But if you're using the default analyzers then a wildcard query will return case-insensitive results.

Example: Post two names in a sample index one is "Sid" and other "sid".

POST sample/sample
{
  "name" : "sid"
}

POST sample/sample
{
  "name" : "Sid"
}

Then perform a wildcard query:

GET sample/_search
{
  "query": {
    "wildcard": {
      "name": {
        "value": "s*"
      }
    }
  }
}

This will return me both the documents:

{
  "took": 10,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 1,
    "hits": [
      {
        "_index": "sample",
        "_type": "sample",
        "_id": "AWRPM87Wb6oopELrnEKE",
        "_score": 1,
        "_source": {
          "name": "Sid"
        }
      },
      {
        "_index": "sample",
        "_type": "sample",
        "_id": "AWRPM9tpb6oopELrnEKF",
        "_score": 1,
        "_source": {
          "name": "sid"
        }
      }
    ]
  }
}

But if you perform a wildcard query on "S*" it will return nothing. Because the default token filter stores the terms in lowercase and the term "Sid" is stored as "sid" in the inverted index.