Composite Aggregation Usage
editComposite Aggregation Usage
editA multi-bucket aggregation that creates composite buckets from different sources.
Unlike the other multi-bucket aggregation the composite aggregation can be used to paginate all buckets from a multi-level aggregation efficiently. This aggregation provides a way to stream all buckets of a specific aggregation similarly to what scroll does for documents.
The composite buckets are built from the combinations of the values extracted/created for each document and each combination is considered as a composite bucket.
Only available in Elasticsearch 6.1.0+
Be sure to read the Elasticsearch documentation on Composite Aggregation.
Fluent DSL example
edita => a .Composite("my_buckets", date => date .Sources(s => s .Terms("branches", t => t .Field(f => f.Branches.Suffix("keyword")) ) .DateHistogram("started", d => d .Field(f => f.StartedOn) .CalendarInterval(DateInterval.Month) ) .Histogram("branch_count", h => h .Field(f => f.RequiredBranches) .Interval(1) ) .GeoTileGrid("geo", h => h .Field(f => f.LocationPoint) .Precision(GeoTilePrecision.Precision12) ) ) .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 CompositeAggregation("my_buckets") { Sources = new List<ICompositeAggregationSource> { new TermsCompositeAggregationSource("branches") { Field = Field<Project>(f => f.Branches.Suffix("keyword")) }, new DateHistogramCompositeAggregationSource("started") { Field = Field<Project>(f => f.StartedOn), CalendarInterval = DateInterval.Month }, new HistogramCompositeAggregationSource("branch_count") { Field = Field<Project>(f => f.RequiredBranches), Interval = 1 }, new GeoTileGridCompositeAggregationSource("geo") { Field = Field<Project>(f => f.LocationPoint), Precision = GeoTilePrecision.Precision12 } }, 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.
{ "my_buckets": { "composite": { "sources": [ { "branches": { "terms": { "field": "branches.keyword" } } }, { "started": { "date_histogram": { "field": "startedOn", "calendar_interval": "month" } } }, { "branch_count": { "histogram": { "field": "requiredBranches", "interval": 1.0 } } }, { "geo": { "geotile_grid": { "field": "locationPoint", "precision": 12 } } } ] }, "aggs": { "project_tags": { "nested": { "path": "tags" }, "aggs": { "tags": { "terms": { "field": "tags.name" } } } } } } }
Handling Responses
editEach Composite aggregation bucket key is a CompositeKey
type, a specialized
IReadOnlyDictionary<string, object>
type with methods to convert values to supported types
response.ShouldBeValid(); var composite = response.Aggregations.Composite("my_buckets"); composite.Should().NotBeNull(); composite.Buckets.Should().NotBeNullOrEmpty(); composite.AfterKey.Should().NotBeNull(); if (TestConfiguration.Instance.InRange(">=6.3.0")) composite.AfterKey.Should() .HaveCount(4) .And.ContainKeys("branches", "started", "branch_count", "geo"); foreach (var item in composite.Buckets) { var key = item.Key; key.Should().NotBeNull(); key.TryGetValue("branches", out string branches).Should().BeTrue(); branches.Should().NotBeNullOrEmpty(); key.TryGetValue("started", out DateTime started).Should().BeTrue(); started.Should().BeAfter(default(DateTime)); key.TryGetValue("branch_count", out int branchCount).Should().BeTrue(); branchCount.Should().BeGreaterThan(0); item.DocCount.Should().BeGreaterThan(0); var nested = item.Nested("project_tags"); nested.Should().NotBeNull(); if (nested.DocCount > 0) { var nestedTerms = nested.Terms("tags"); nestedTerms.Buckets.Count.Should().BeGreaterThan(0); } }
Missing buckets
editBy default documents without a value for a given source are ignored.
It is possible to include them in the response by setting missing_bucket to true
(defaults to false
):
Only available in Elasticsearch 6.4.0+
Fluent DSL example
edita => a .Composite("my_buckets", date => date .Sources(s => s .Terms("branches", t => t .Field(f => f.Branches.Suffix("keyword")) .MissingBucket() .Order(SortOrder.Ascending) ) ) .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 CompositeAggregation("my_buckets") { Sources = new List<ICompositeAggregationSource> { new TermsCompositeAggregationSource("branches") { Field = Field<Project>(f => f.Branches.Suffix("keyword")), MissingBucket = true, Order = SortOrder.Ascending } }, 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.
{ "my_buckets": { "composite": { "sources": [ { "branches": { "terms": { "field": "branches.keyword", "order": "asc", "missing_bucket": true } } } ] }, "aggs": { "project_tags": { "nested": { "path": "tags" }, "aggs": { "tags": { "terms": { "field": "tags.name" } } } } } } }
Handling Responses
editEach Composite aggregation bucket key is an CompositeKey
, a specialized
IReadOnlyDictionary<string, object>
type with methods to convert values to supported types
response.ShouldBeValid(); var composite = response.Aggregations.Composite("my_buckets"); composite.Should().NotBeNull(); composite.Buckets.Should().NotBeNullOrEmpty(); composite.AfterKey.Should().NotBeNull(); if (TestConfiguration.Instance.InRange(">=6.3.0")) composite.AfterKey.Should().HaveCount(1).And.ContainKeys("branches"); var i = 0; foreach (var item in composite.Buckets) { var key = item.Key; key.Should().NotBeNull(); key.TryGetValue("branches", out string branches).Should().BeTrue("expected to find 'branches' in composite bucket"); if (i == 0) branches.Should().BeNull("First key should be null as we expect to have some projects with no branches"); else branches.Should().NotBeNullOrEmpty(); var nested = item.Nested("project_tags"); nested.Should().NotBeNull(); var nestedTerms = nested.Terms("tags"); nestedTerms.Buckets.Count.Should().BeGreaterThan(0); i++; }