ElasticSearch Fields Mapping to String by default when indexing - elasticsearch

Question

Let me first explain my scenario.
I am fetching data from RDBMS and pushing it into ElasticSearch.
Fetched Results are in the form of List and i am preparing bulk index request like this:
BulkRequestBuilder bulkRequest = client.prepareBulk();
for (Map<String,Object> singleDataRow : ResultSet)
{
IndexRequest indexRequest = new IndexRequest("testindex","testtype",singleDataRow.getObject("NAME"));
bulkRequest.add(indexRequest);
}
bulkRequest.execute().actionGet();
My Map = includes Map of string to string, string to big decimal, string to big integer etc.
eg.
{ BIRTHDATE : 2015-03-05 , NAME : deepankar , AGE : 22 , AMOUNT : 15.5 }
But when i see the mapping of my testtype in testindex, all mapping of fields are of "type" : "string"
Why the fields does not maps to "type": "string" , or "type" : "long" , and even "type" : "date" as elasticsearch does it by default?

Answer 1

Elasticsearch will attempt to 'guess' the field type by the first insert, unless you create and map fields beforehand.
There are two possible reasons why your fields are being indexed as string instead of long or any other type:
You're not really sending these fields as int, so you're sending '10' instead of 10
You've already inserted at least 1 document that had a string value for that field, so if you've inserted your first document with AGE: '22' Elasticsearch will set that field to type: string and any future inserts will have a string value.
If you want to make sure, you can delete the current index, re-create it and manually set up mapping before inserting the first document, like so:
curl -XPUT 'http://localhost:9200/testindex/_mapping/testmapping' -d '
{
"testmapping" : {
"properties" : {
"birthdate" : { "type" : "date", "format": "dateOptionalTime" },
"name" : { "type" : "string" },
"age" : { "type" : "long" },
"amount" : { "type" : "double" }
}
}
}
'