How to store country/state/city information in Elasticsearch

i.e there are many countries
each country has many states
each state has many cities

Its easier to store in a relational database, but if I want to store all possible combinations how should I do this in Elasticsearch

I want to store the country, state, city location in a certain index containing user information

i.e users (first_name, last_name, country, state, city ...)

Solution

Please don't confuse Elasticsearch with RDBMS and as you have not mentioned what is your use-case ie its full-text search or aggregation, I will show you how to achieve the full-text search with your data and its easy to achieve and don't require much configuration/complexity to achieve it.

As one user at a time can stay only in one city, state, and country but still if you want to store multiple options for the users that also can be done, you just have to index the , separated values.

If you need the aggregations on these fields then please index these fields as keyword so that you can do aggregations on it.

Complete example for full-text search

Index mapping

{
  "mappings" :{
      "properties" :{
          "first_name" :{
              "type" : "text"
          },
          "last_name" :{
              "type" : "text"
          },
          "country" :{
              "type" : "text"
          },
          "state" :{
              "type" : "text"
          },
          "city" :{
              "type" : "text"
          }
      }
  }
}

Index sample docs

{
  "first_name" : "abc",
  "last_name" : "xyz",
  "country": "USA",
  "state" : "California",
  "city" : "SF"
}

{
  "first_name" : "opster",
  "last_name" : "ninja",
  "country": "Israel",
  "state" : "na",
  "city" : "tel aviv"
}

{
  "first_name" : "abc",
  "last_name" : "xyz",
  "country": "USA",
  "state" : "California, washintion", // not two state
  "city" : "SF"
}

Now search for California will return first and third docs as shown below

{
    "query": {
        "match": {
            "state": "california"
        }
    }
}

And search results

 "hits": [
            {
                "_index": "so_63601020",
                "_type": "_doc",
                "_id": "3",
                "_score": 0.38845783,
                "_source": {
                    "first_name": "abc",
                    "last_name": "xyz",
                    "country": "USA",
                    "state": "California",
                    "city": "SF"
                }
            },
            {
                "_index": "so_63601020",
                "_type": "_doc",
                "_id": "2",
                "_score": 0.2863813,
                "_source": {
                    "first_name": "foo",
                    "last_name": "bar",
                    "country": "USA",
                    "state": "California, washington",
                    "city": "SF"
                }
            }
        ]