Elasticsearch, get average document length

Question

Is there any better way in elasticsearch (other than issuing a match all query and manually averaging over the length of all returned documents) to get the average document

Answer 1

I have used this code (I have the _source enabled)

{
  "query" : {"match_all" : {}},
  "aggs":{
    "avg_length" : { "avg" : { "script" : "_source.toString().length()"}}
  }
}

Well, the chars .. .if the string are UTF-8 to get the bytes:

{
  "query" : {"match_all" : {}},
  "aggs":{
    "avg_length" : { "avg" : { "script" : "_source.toString().getBytes(\"UTF-8\").length"}}
  }
}