How Can i get max id of indexed documents

I am new to elastic search. I indexed few of documents and i want to find the max id which ever inserted across the documents.

My URL something like ":/books/dramabooks/_search?size=0"
{
"aggs" : {
"max_id" : { "max" : { "field" : "id" } }
}
} --POST URL

Response:
{"took":75,"timed_out":false,"_shards":{"total":5,"successful":5,"failed":0},"hits":{"total":5,"max_score":0.0,"hits":[]},"aggregations":{"max_id":{"value":null}}}

Note:request returning max_id value as null.

Could you please provide right query that should return maximum value of id.

Thanks in advance.

Hey!

ID's are usually a SHA or UUID! There is no pattern of numerical ascendancy/descendancy to them to find out the max of, unless you are overriding the ID upon insertion!