[Backport 7.9] Add moving_percentiles aggregation

docs/aggregations.asciidoc

@@ -277,6 +277,8 @@ There are many different types of pipeline aggregation, each computing different
 
 * <<moving-function-aggregation-usage,Moving Function Aggregation Usage>>
 
+* <<moving-percentiles-aggregation-usage,Moving Percentiles Aggregation Usage>>
+
 * <<normalize-aggregation-usage,Normalize Aggregation Usage>>
 
 * <<percentiles-bucket-aggregation-usage,Percentiles Bucket Aggregation Usage>>
@@ -323,6 +325,8 @@ include::aggregations/pipeline/moving-average/moving-average-simple-aggregation-
 
 include::aggregations/pipeline/moving-function/moving-function-aggregation-usage.asciidoc[]
 
+include::aggregations/pipeline/moving-percentiles/moving-percentiles-aggregation-usage.asciidoc[]
+
 include::aggregations/pipeline/normalize/normalize-aggregation-usage.asciidoc[]
 
 include::aggregations/pipeline/percentiles-bucket/percentiles-bucket-aggregation-usage.asciidoc[]

docs/aggregations/pipeline/moving-percentiles/moving-percentiles-aggregation-usage.asciidoc

@@ -0,0 +1,110 @@
+:ref_current: https://www.elastic.co/guide/en/elasticsearch/reference/master
+
+:github: https://github.com/elastic/elasticsearch-net
+
+:nuget: https://www.nuget.org/packages
+
+////
+IMPORTANT NOTE
+==============
+This file has been generated from https://github.com/elastic/elasticsearch-net/tree/master/src/Tests/Tests/Aggregations/Pipeline/MovingPercentiles/MovingPercentilesAggregationUsageTests.cs. 
+If you wish to submit a PR for any spelling mistakes, typos or grammatical errors for this file,
+please modify the original csharp file found at the link and submit the PR with that change. Thanks!
+////
+
+[[moving-percentiles-aggregation-usage]]
+=== Moving Percentiles Aggregation Usage
+
+Given an ordered series of percentiles, the Moving Percentile aggregation will slide a window across those
+percentiles and allow the user to compute the cumulative percentile.
+
+This is conceptually very similar to the Moving Function pipeline aggregation, except it works on the percentiles sketches instead of the actual buckets values.
+
+NOTE: Available in Elasticsearch 7.9.0+ with at least basic license level
+
+==== Fluent DSL example
+
+[source,csharp]
+----
+a => a
+.DateHistogram("projects_started_per_month", dh => dh
+    .Field(p => p.StartedOn)
+    .CalendarInterval(DateInterval.Month)
+    .MinimumDocumentCount(0)
+    .Aggregations(aa => aa
+        .Percentiles("percentiles", sm => sm
+            .Field(p => p.NumberOfCommits)
+        )
+        .MovingPercentiles("moving_percentiles", mv => mv
+            .BucketsPath("percentiles")
+            .Window(10)
+        )
+    )
+)
+----
+
+==== Object Initializer syntax example
+
+[source,csharp]
+----
+new DateHistogramAggregation("projects_started_per_month")
+{
+    Field = "startedOn",
+    CalendarInterval = DateInterval.Month,
+    MinimumDocumentCount = 0,
+    Aggregations =
+        new PercentilesAggregation("percentiles", "numberOfCommits")
+        && new MovingPercentilesAggregation("moving_percentiles", "percentiles")
+        {
+            Window = 10
+        }
+}
+----
+
+[source,javascript]
+.Example json output
+----
+{
+  "projects_started_per_month": {
+    "date_histogram": {
+      "field": "startedOn",
+      "calendar_interval": "month",
+      "min_doc_count": 0
+    },
+    "aggs": {
+      "percentiles": {
+        "percentiles": {
+          "field": "numberOfCommits"
+        }
+      },
+      "moving_percentiles": {
+        "moving_percentiles": {
+          "buckets_path": "percentiles",
+          "window": 10
+        }
+      }
+    }
+  }
+}
+----
+
+==== Handling Responses
+
+[source,csharp]
+----
+response.ShouldBeValid();
+
+var projectsPerMonth = response.Aggregations.DateHistogram("projects_started_per_month");
+projectsPerMonth.Should().NotBeNull();
+projectsPerMonth.Buckets.Should().NotBeNull();
+projectsPerMonth.Buckets.Count.Should().BeGreaterThan(0);
+
+// percentiles not calculated for the first bucket
+foreach (var item in projectsPerMonth.Buckets.Skip(1))
+{
+    var movingPercentiles = item.MovingPercentiles("moving_percentiles");
+    movingPercentiles.Should().NotBeNull();
+    movingPercentiles.Items.Should().NotBeNull();
+}
+----
+

src/Nest/Aggregations/AggregateDictionary.cs

@@ -98,6 +98,8 @@ public ScriptedMetricAggregate ScriptedMetric(string key)
 
 		public PercentilesAggregate PercentilesBucket(string key) => TryGet<PercentilesAggregate>(key);
 
+		public PercentilesAggregate MovingPercentiles(string key) => TryGet<PercentilesAggregate>(key);
+
 		public PercentilesAggregate PercentileRanks(string key) => TryGet<PercentilesAggregate>(key);
 
 		public TopHitsAggregate TopHits(string key) => TryGet<TopHitsAggregate>(key);

src/Nest/Aggregations/AggregationContainer.cs

@@ -199,6 +199,10 @@ public interface IAggregationContainer
 		[DataMember(Name = "moving_fn")]
 		IMovingFunctionAggregation MovingFunction { get; set; }
 
+		/// <inheritdoc cref="IMovingPercentilesAggregation"/>
+		[DataMember(Name = "moving_percentiles")]
+		IMovingPercentilesAggregation MovingPercentiles { get; set; }
+
 		[DataMember(Name = "nested")]
 		INestedAggregation Nested { get; set; }
 
@@ -358,6 +362,9 @@ public class AggregationContainer : IAggregationContainer
 
 		public IMovingFunctionAggregation MovingFunction { get; set; }
 
+		/// <inheritdoc cref="IMovingPercentilesAggregation"/>
+		public IMovingPercentilesAggregation MovingPercentiles { get; set; }
+
 		public INestedAggregation Nested { get; set; }
 
 		/// <inheritdoc cref="INormalizeAggregation"/>
@@ -518,6 +525,8 @@ public class AggregationContainerDescriptor<T> : DescriptorBase<AggregationConta
 
 		IMovingFunctionAggregation IAggregationContainer.MovingFunction { get; set; }
 
+		IMovingPercentilesAggregation IAggregationContainer.MovingPercentiles { get; set; }
+
 		INestedAggregation IAggregationContainer.Nested { get; set; }
 
 		INormalizeAggregation IAggregationContainer.Normalize { get; set; }
@@ -809,6 +818,11 @@ Func<MovingFunctionAggregationDescriptor, IMovingFunctionAggregation> selector
 		) =>
 			_SetInnerAggregation(name, selector, (a, d) => a.MovingFunction = d);
 
+		public AggregationContainerDescriptor<T> MovingPercentiles(string name,
+			Func<MovingPercentilesAggregationDescriptor, IMovingPercentilesAggregation> selector
+		) =>
+			_SetInnerAggregation(name, selector, (a, d) => a.MovingPercentiles = d);
+
 		public AggregationContainerDescriptor<T> CumulativeSum(string name,
 			Func<CumulativeSumAggregationDescriptor, ICumulativeSumAggregation> selector
 		) =>

src/Nest/Aggregations/Pipeline/MovingPercentiles/MovingPercentilesAggregation.cs

@@ -0,0 +1,61 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Runtime.Serialization;
+using Elasticsearch.Net.Utf8Json;
+
+namespace Nest
+{
+	/// <summary>
+	/// the Moving Percentile aggregation will slide a window across those percentiles and allow the user to compute the cumulative percentile.
+	/// </summary>
+	[InterfaceDataContract]
+	[ReadAs(typeof(MovingPercentilesAggregation))]
+	public interface IMovingPercentilesAggregation : IPipelineAggregation
+	{
+		/// <summary>
+		/// The size of window to "slide" across the histogram.
+		/// </summary>
+		[DataMember(Name ="window")]
+		int? Window { get; set; }
+
+		/// <summary>
+		/// Shift of window position.
+		/// </summary>
+		[DataMember(Name ="shift")]
+		int? Shift { get; set; }
+	}
+
+	/// <inheritdoc cref="IMovingPercentilesAggregation"/>
+	public class MovingPercentilesAggregation
+		: PipelineAggregationBase, IMovingPercentilesAggregation
+	{
+		internal MovingPercentilesAggregation() { }
+
+		public MovingPercentilesAggregation(string name, SingleBucketsPath bucketsPath)
+			: base(name, bucketsPath) { }
+
+		/// <inheritdoc cref="IMovingPercentilesAggregation.Window"/>
+		public int? Window { get; set; }
+
+		/// <inheritdoc cref="IMovingPercentilesAggregation.Shift"/>
+		public int? Shift { get; set; }
+
+		internal override void WrapInContainer(AggregationContainer c) => c.MovingPercentiles = this;
+	}
+
+	public class MovingPercentilesAggregationDescriptor
+		: PipelineAggregationDescriptorBase<MovingPercentilesAggregationDescriptor, IMovingPercentilesAggregation, SingleBucketsPath>
+			, IMovingPercentilesAggregation
+	{
+		int? IMovingPercentilesAggregation.Window { get; set; }
+		int? IMovingPercentilesAggregation.Shift { get; set; }
+
+		/// <inheritdoc cref="IMovingPercentilesAggregation.Window"/>
+		public MovingPercentilesAggregationDescriptor Window(int? windowSize) => Assign(windowSize, (a, v) => a.Window = v);
+
+		/// <inheritdoc cref="IMovingPercentilesAggregation.Shift"/>
+		public MovingPercentilesAggregationDescriptor Shift(int? shift) => Assign(shift, (a, v) => a.Shift = v);
+	}
+}

src/Nest/Aggregations/Visitor/AggregationVisitor.cs

@@ -114,6 +114,8 @@ public interface IAggregationVisitor
 
 		void Visit(IMovingAverageAggregation aggregation);
 
+		void Visit(IMovingPercentilesAggregation aggregation);
+
 		void Visit(ICumulativeSumAggregation aggregation);
 
 		void Visit(ICumulativeCardinalityAggregation aggregation);
@@ -219,6 +221,8 @@ public virtual void Visit(ISerialDifferencingAggregation aggregation) { }
 
 		public virtual void Visit(IMovingAverageAggregation aggregation) { }
 
+		public virtual void Visit(IMovingPercentilesAggregation aggregation) { }
+
 		public virtual void Visit(IMinBucketAggregation aggregation) { }
 
 		public virtual void Visit(IDerivativeAggregation aggregation) { }

src/Nest/Aggregations/Visitor/AggregationWalker.cs

@@ -117,6 +117,7 @@ public void Walk(IAggregationContainer aggregation, IAggregationVisitor visitor)
 				Accept(v, d.Aggregations);
 			});
 			AcceptAggregation(aggregation.MovingAverage, visitor, (v, d) => v.Visit(d));
+			AcceptAggregation(aggregation.MovingPercentiles, visitor, (v, d) => v.Visit(d));
 			AcceptAggregation(aggregation.Nested, visitor, (v, d) =>
 			{
 				v.Visit(d);

tests/Tests/Aggregations/Pipeline/MovingPercentiles/MovingPercentilesAggregationUsageTests.cs

@@ -0,0 +1,109 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System;
+using System.Linq;
+using Elastic.Elasticsearch.Xunit.XunitPlumbing;
+using FluentAssertions;
+using Nest;
+using Tests.Core.Extensions;
+using Tests.Core.ManagedElasticsearch.Clusters;
+using Tests.Domain;
+using Tests.Framework.EndpointTests.TestState;
+
+namespace Tests.Aggregations.Pipeline.MovingPercentiles
+{
+	/**
+	 * Given an ordered series of percentiles, the Moving Percentile aggregation will slide a window across those
+	 * percentiles and allow the user to compute the cumulative percentile.
+     *
+     * This is conceptually very similar to the Moving Function pipeline aggregation, except it works on the percentiles sketches instead of the actual buckets values.
+	 *
+	 * NOTE: Available in Elasticsearch 7.9.0+ with at least basic license level
+	 */
+	[SkipVersion("<7.9.0", "introduced in 7.9.0+")]
+	public class MovingPercentilesAggregationUsageTests : AggregationUsageTestBase
+	{
+		public MovingPercentilesAggregationUsageTests(ReadOnlyCluster cluster, EndpointUsage usage) : base(cluster, usage) { }
+
+		protected override object AggregationJson => new
+		{
+			projects_started_per_month = new
+			{
+				date_histogram = new
+				{
+					field = "startedOn",
+					calendar_interval = "month",
+					min_doc_count = 0
+				},
+				aggs = new
+				{
+					percentiles = new
+					{
+						percentiles = new
+						{
+							field = "numberOfCommits"
+						}
+					},
+					moving_percentiles = new
+					{
+						moving_percentiles = new
+						{
+							buckets_path = "percentiles",
+							window = 10,
+						}
+					}
+				}
+			}
+		};
+
+		protected override Func<AggregationContainerDescriptor<Project>, IAggregationContainer> FluentAggs => a => a
+			.DateHistogram("projects_started_per_month", dh => dh
+				.Field(p => p.StartedOn)
+				.CalendarInterval(DateInterval.Month)
+				.MinimumDocumentCount(0)
+				.Aggregations(aa => aa
+					.Percentiles("percentiles", sm => sm
+						.Field(p => p.NumberOfCommits)
+					)
+					.MovingPercentiles("moving_percentiles", mv => mv
+						.BucketsPath("percentiles")
+						.Window(10)
+					)
+				)
+			);
+
+		protected override AggregationDictionary InitializerAggs =>
+			new DateHistogramAggregation("projects_started_per_month")
+			{
+				Field = "startedOn",
+				CalendarInterval = DateInterval.Month,
+				MinimumDocumentCount = 0,
+				Aggregations =
+					new PercentilesAggregation("percentiles", "numberOfCommits")
+					&& new MovingPercentilesAggregation("moving_percentiles", "percentiles")
+					{
+						Window = 10
+					}
+			};
+
+		protected override void ExpectResponse(ISearchResponse<Project> response)
+		{
+			response.ShouldBeValid();
+
+			var projectsPerMonth = response.Aggregations.DateHistogram("projects_started_per_month");
+			projectsPerMonth.Should().NotBeNull();
+			projectsPerMonth.Buckets.Should().NotBeNull();
+			projectsPerMonth.Buckets.Count.Should().BeGreaterThan(0);
+
+			// percentiles not calculated for the first bucket
+			foreach (var item in projectsPerMonth.Buckets.Skip(1))
+			{
+				var movingPercentiles = item.MovingPercentiles("moving_percentiles");
+				movingPercentiles.Should().NotBeNull();
+				movingPercentiles.Items.Should().NotBeNull();
+			}
+		}
+	}
+}