Exclude only 1 field from indexing - elasticsearch

Question

I need your help with ElasticSearch field indexes.
I'm sending Jsons to ES and I have only 1 field that I send XML and I never search on this field.
I need your help to exclude ONLY this field from indexing. The field that I would like to exclude is: rawXml
Please let me know if you need more details from me.
Is this possible?
This is the Json i'm sending now :
{
"_index": "logstash-2015.05.05",
"_type": "XXXXX",
"_id": "XXXXXX",
"_score": null,
"_source": {
"#version": 1,
"#timestamp": "2015-05-05T00:00:11.489Z",
"host": "XXXXXXXXX",
"application_name": "XXXXXXX",
"logger_name": "XXXXXXXXX",
"level": "DEBUG",
"thread_name": "XXXXXXX",
"name": "XXXXXXXX",
"rawXml": "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n<XXXXX xmlns=\"http://XXXXXXXX\" Version=\"14.000\">\n <POS>\n <Source DKNumber=\"XXXXXX\"/>\n </POS>\n <Unique>\n <ID PCC=\"XXXXX\" GDS=\"XXXXX\" NAME=\"XXXXXX\" TYPE=\"XXXXXX\"/>\n </Unique>\n</OpenHotelHubSessionCreateRQ>\n",
"type": "XXXXXXXX",
"message": "Event: XXXXXXX",
"requestContext": {
"wml-locale": "en_AU",
"accountId": XXXXXXX,
"agentName": "XXXXXXX",
"deviceType": "XXXXXX",
"cwtTraveller": {
"clientTopGuid": "XXXXX",
"travellerGuid": "XXXXXXX",
"clientTopTravelerTypeGuid": "XXXXXX",
"clientSubGuid": "XXXXXXXX"
},
"providerSessionId": null,
"variantId": X
},
"path": "XXXXXXXXXXX",
"hostname": "XXXXXXXXX"
},
"sort": [
1430784011489
]
}