NEST Aggregate similar to SQL Group By - elasticsearch

Question

This is my class when inserting to ES
public class BasicDoc
{
public string Name { get; set; }
public string Url { get; set; }
}
I managed successfully insert my document to ES using NEST. But I'm having trouble to do a aggregation. My goals is to have something similar to SQL Group By. What I did so far:
var response = elastic.Search<BasicDoc>(s => s
.Aggregations(a => a
.Terms("group_by_url", st => st
.Field(o => o.Url)
))
);
I tried to aggregate my document based on BasicDoc.Url. Say I have these in my ES:
/api/call1/v1
/api/call2/v1
/api/call1/v1
When I debug, I my Nest.BucketAggregate will have 4 Items key which is api,call1, call2 and v1. I was expecting only 2 which are /api/call1/v1 and /api/call2/v1. What I'm doing wrong?

Answer 1

You currently have analysis set up on your Url property which means that it will be tokenized by the standard analyzer and terms stored in the inverted index. If you need to be able to search on Uri and also need to aggregate on it, then you may consider mapping it as a multi_field where one field mapping analyzes it and another does not. Here's an example index creation with mapping
client.CreateIndex("index-name", c => c
.Mappings(m => m
.Map<BasicDoc>(mm => mm
.AutoMap()
.Properties(p => p
.String(s => s
.Name(n => n.Url)
.Fields(f => f
.String(ss => ss
.Name("raw")
.NotAnalyzed()
)
)
)
)
)
)
);
When you perform your aggregation, you can now use the Uri raw field
var response = client.Search<BasicDoc>(s => s
.Size(0)
.Aggregations(a => a
.Terms("group_by_url", st => st
.Field(o => o.Url.Suffix("raw"))
)
)
);