How to search content without duplicate

[Sharon_wsf (雪中的凤凰)]

Dear teams,

my elasticsearch is using 2.4.0

my search coding normal is as below:
POST /news/TRKD/_search {
"query": { "bool": { "must": [ { "range": { "CDate": { "gt": "2017-04-19T18:23:06" , "lte": "2017-04-19T23:59:59" } } } ] } }, "from": 0, "size": 100, "sort": [ { "CDate": { "order": "desc" } } ]
}

my screen will be as below:

how to output of searching no duplicate if the filed of 'tag' found have duplicate, output only show one of them?

Thanks..