Elasticsearch uses wrong Case Folding for Unicode Characters
You should try to use the Turkish Language Analyzer in your setting.
{ "mappings": { "names": { "properties": { "name": { "type": "string", "analyzer": "turkish" } } } }}As you can see in the implementation details, it also defines a turkish_lowercase so I guess it'll take care of your problems for you. If you don't want all the other features of the Turkish Analyzer, define a custom one with only turkish_lowercase
If you need a full text search on your name field, you should also change the query method to match query, which is the basic full text search method on a single field.
{ "query": { "match": { "name": "bahadır" } }}On the other hand, query string query is more complex and searches on multiple fields allowing an advanced syntax; It also has an option to pass the analyzer you want to use, so if you really needed this kind of query you should have tried passing "analyzer": "turkish" within the query. I'm not an expert of query string query though.