That just doesn't feel right. I am not totally sure why yet, but I can reproduce it. When you run [this script](https://gist.github.com/imotov/a3792c0f1094c71dd079) on an empty one-node cluster it returns:
```
      "fielddata_breaker" : {
        "maximum_size_in_bytes" : -1,
        "maximum_size" : "-1b",
        "estimated_size_in_bytes" : -4,
        "estimated_size" : "-4b",
        "overhead" : 1.03
      }
```