In Elasticsearch 5.0, dots are permitted in field names and each step in the path is interpreted as an object field, except for the last step. For instance, indexing the following document in Elasticsearch 5.0:

{
  "server.latency.max": 100
}

would result in the following mapping:

{
  "properties": {
    "server": {
      "type": "object",
      "properties": {
        "latency": {
          "type": "object",
          "properties": {
            "max": {
              "type": "long"
            }
          }
        }
      }
    }
  }
}

Elasticsearch 2.x does not support this dots-to-object transformation and so dots in field names are not allowed in versions 2.0 - 2.3.

Enabling support for dots in field namesedit

Elasticsearch 2.4.0 adds a system property called mapper.allow_dots_in_name which will disable the check for dots in field names. You can enable this system property as follows:

export ES_JAVA_OPTS="-Dmapper.allow_dots_in_name=true"
./bin/elasticsearch

(ES_JAVA_OPTS can be set in the /etc/default/elasticsearch file if you’re using the Debian package, or in the /etc/sysconfig/elasticsearch file if you’re using the RPM.)

With this sytem property enabled, indexing the document above in 2.4.0 will result in the following mapping:

{
  "properties": {
    "server.latency.max": {
      "type": "long"
    }
  }
}

Upgrading fields with dots to 5.xedit

Indices created in 1.x must be reindexed in 2.4 before being upgraded to 5.x, regardless of whether they have fields with dots or not. Alternatively, indices from a 1.x cluster can be imported directly into a 5.x cluster using reindex-from-remote.

Indices created in 2.4 can be upgraded to 5.x directly, as long as there are no conflicts (see below). If there are dots in field names, the mapping will be automatically updated to the object-style mapping shown in Dots in field names.

{
  "properties": {
    "server.latency": {
      "type": "long"
    },
    "server.name": {
      "type": "string"
    }
  }
}

{
  "properties": {
    "server.latency": {
      "type": "long"
    },
    "server": {
      "type": "string"
    }
  }
}