Auto Date Histogram Aggregation Usage
editAuto Date Histogram Aggregation Usage
editA multi-bucket aggregation similar to the Date Histogram Aggregation except instead of providing an interval to use as the width of each bucket, a target number of buckets is provided indicating the number of buckets needed and the interval of the buckets is automatically chosen to best achieve that target. The number of buckets returned will always be less than or equal to this target number.
When specifying a format and extended_bounds or missing, in order for Elasticsearch to be able to parse
the serialized DateTime of extended_bounds or missing correctly, the date_optional_time format is included
as part of the format value.
Be sure to read the Elasticsearch documentation on Auto Date Histogram Aggregation.
Fluent DSL example
edita => a
.AutoDateHistogram("projects_started_per_month", date => date
.Field(p => p.StartedOn)
.Buckets(10)
.Format("yyyy-MM-dd'T'HH:mm:ss")
.Missing(FixedDate)
.Aggregations(childAggs => childAggs
.Nested("project_tags", n => n
.Path(p => p.Tags)
.Aggregations(nestedAggs => nestedAggs
.Terms("tags", avg => avg.Field(p => p.Tags.First().Name))
)
)
)
)
Object Initializer syntax example
editnew AutoDateHistogramAggregation("projects_started_per_month")
{
Field = Field<Project>(p => p.StartedOn),
Buckets = 10,
Format = "yyyy-MM-dd'T'HH:mm:ss",
Missing = FixedDate,
Aggregations = new NestedAggregation("project_tags")
{
Path = Field<Project>(p => p.Tags),
Aggregations = new TermsAggregation("tags")
{
Field = Field<Project>(p => p.Tags.First().Name)
}
}
}
Example json output.
{
"projects_started_per_month": {
"auto_date_histogram": {
"field": "startedOn",
"buckets": 10,
"format": "yyyy-MM-dd'T'HH:mm:ss||date_optional_time",
"missing": "2015-06-06T12:01:02.123"
},
"aggs": {
"project_tags": {
"nested": {
"path": "tags"
},
"aggs": {
"tags": {
"terms": {
"field": "tags.name"
}
}
}
}
}
}
}
Handling responses
editThe AggregateDictionary found on `.Aggregations on SearchResponse<T> has several helper methods
so we can fetch our aggregation results easily in the correct type.
Be sure to read more about these helper methods
response.ShouldBeValid();
var dateHistogram = response.Aggregations.AutoDateHistogram("projects_started_per_month");
dateHistogram.Should().NotBeNull();
dateHistogram.AutoInterval.Should().NotBeNull();
dateHistogram.Buckets.Should().NotBeNull();
dateHistogram.Buckets.Count.Should().BeGreaterThan(1);
foreach (var item in dateHistogram.Buckets)
{
item.Date.Should().NotBe(default);
item.DocCount.Should().BeGreaterThan(0);
var nested = item.Nested("project_tags");
nested.Should().NotBeNull();
var nestedTerms = nested.Terms("tags");
nestedTerms.Buckets.Count.Should().BeGreaterThan(0);
}