Custom Type fields

Option 1

Scenario with the old approach where one index may have several different mapping types. We can see two types: user and tweet, each with the following properties (equivalent of columns in RDB):

user

• name
• user_name
• email

tweet

• content
• user_name
• tweeted_at

Where user_name will relate users and tweets

PUT twitter
{
  "mappings": {
    "user": {
      "properties": {
        "name": { "type": "text" },
        "user_name": { "type": "keyword" },
        "email": { "type": "keyword" }
      }
    },
    "tweet": {
      "properties": {
        "content": { "type": "text" },
        "user_name": { "type": "keyword" },
        "tweeted_at": { "type": "date" }
      }
    }
  }
}

Populating the index with one user and one tweet

PUT twitter/user/kimchy
{
  "name": "Shay Banon",
  "user_name": "kimchy",
  "email": "shay@kimchy.com"
}

PUT twitter/tweet/1
{
  "user_name": "kimchy",
  "tweeted_at": "2017-10-24T09:00:00Z",
  "content": "Types are going away"
}

Option 2

You can achieve the same thing by adding a custom type field as follows:

PUT twitter
{
  "mappings": {
    "_doc": {
      "properties": {
        "type": { "type": "keyword" },   **New_field**
        "name": { "type": "text" },
        "user_name": { "type": "keyword" },
        "email": { "type": "keyword" },
        "content": { "type": "text" },
        "tweeted_at": { "type": "date" }
      }
    }
  }
}

Now we would populate the index like this:

PUT twitter/_doc/user-kimchy
{
  "type": "user", 
  "name": "Shay Banon",
  "user_name": "kimchy",
  "email": "shay@kimchy.com"
}

PUT twitter/_doc/tweet-1
{
  "type": "tweet", 
  "user_name": "kimchy",
  "tweeted_at": "2017-10-24T09:00:00Z",
  "content": "Types are going away"
}

To retrieve all tweets of a user named kimchy we would need a query like:

GET twitter/_search
{
  "query": {
    "bool": {
      "must": {
        "match": {
          "user_name": "kimchy"
        }
      },
      "filter": {
        "match": {
          "type": "tweet" 
        }
      }
    }
  }
}