A newer version is available. For the latest information, see the
current release documentation.
Rare Terms Aggregation Usageedit
A multi-bucket value source based aggregation which finds "rare" terms — terms that are at the long-tail of the distribution and are not frequent. Conceptually, this is like a terms aggregation that is sorted by _count ascending. As noted in the terms aggregation docs, actually ordering a terms agg by count ascending has unbounded error. Instead, you should use the rare_terms aggregation.
Valid only in Elasticsearch 7.3.0+
See the Elasticsearch documentation on rare terms aggregation for more detail.
Fluent DSL exampleedit
a => a
.RareTerms("names", st => st
.Field(p => p.Name)
.Missing("n/a")
.MaximumDocumentCount(5)
.Precision(0.001)
.Meta(m => m
.Add("foo", "bar")
)
)
Object Initializer syntax exampleedit
new RareTermsAggregation("names")
{
Field = Infer.Field<Project>(p => p.Name),
MaximumDocumentCount = 5,
Precision = 0.001,
Missing = "n/a",
Meta = new Dictionary<string, object> { { "foo", "bar" } }
}
Example json output.
{
"names": {
"meta": {
"foo": "bar"
},
"rare_terms": {
"field": "name",
"max_doc_count": 5,
"missing": "n/a",
"precision": 0.001
}
}
}
Handling Responsesedit
response.ShouldBeValid();
var rareTerms = response.Aggregations.RareTerms("names");
rareTerms.Should().NotBeNull();
rareTerms.Buckets.Should().NotBeNull();
rareTerms.Buckets.Count.Should().BeGreaterThan(0);
foreach (var item in rareTerms.Buckets)
{
item.Key.Should().NotBeNullOrEmpty();
item.DocCount.Should().BeGreaterOrEqualTo(1);
}
rareTerms.Meta.Should().NotBeNull().And.HaveCount(1);
rareTerms.Meta["foo"].Should().Be("bar");