elasticsearch unique values aggregation - elasticsearch

Question

I want to get the unique values from elasticsearch in the field named "name",
i do not know how can i put the condition where the values have to be unique.
The purpose of this work is the fetch all the unique names from the elasticsearch database.
So basically what i need is a aggregation query that fetch the unique values
Can someone help me to fix this issue, thanks a lot in advanced.

Answer 1

You can use a terms aggregation on a field which is not_analyzed.
However, this is by default limited to the 10 most popular terms. You can change this by updating the size parameter of the terms aggregation. Setting it to 0 will allow you to have up to Integer.MAX_VALUE different terms (see the documentation here).
Here is an example mapping:
POST terms
{
"mappings":{
"test":{
"properties":{
"title":{
"type":"string",
"index":"not_analyzed"
}
}
}
}
}
Adding some documents :
POST terms/test
{
"title":"Foundation"
}
POST terms/test
{
"title":"Foundation & Empire"
}
Finally, the request :
POST terms/_search?search_type=count
{
"aggs": {
"By Title": {
"terms": {
"field": "title",
"size": 0
}
}
}
}
will give you what you need :
"aggregations": {
"By Title": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "Foundation",
"doc_count": 1
},
{
"key": "Foundation & Empire",
"doc_count": 1
}
]
}
}
Be aware that if you have a large number of terms, this request will be very expensive to execute.