Histogram field type support for min/max aggregations (#62532)

Implement min/max aggregations for histogram fields.

Closes #60951

docs/reference/aggregations/metrics/max-aggregation.asciidoc

@@ -139,3 +139,54 @@ POST /sales/_search
 
 <1> Documents without a value in the `grade` field will fall into the same
 bucket as documents that have the value `10`.
+
+[[search-aggregations-metrics-max-aggregation-histogram-fields]]
+==== Histogram fields
+
+When `max` is computed on <<histogram,histogram fields>>, the result of the aggregation is the maximum
+of all elements in the `values` array. Note, that the `counts` array of the histogram is ignored.
+
+For example, for the following index that stores pre-aggregated histograms with latency metrics for different networks:
+
+[source,console]
+--------------------------------------------------
+PUT metrics_index/_doc/1
+{
+  "network.name" : "net-1",
+  "latency_histo" : {
+      "values" : [0.1, 0.2, 0.3, 0.4, 0.5], <1>
+      "counts" : [3, 7, 23, 12, 6] <2>
+   }
+}
+
+PUT metrics_index/_doc/2
+{
+  "network.name" : "net-2",
+  "latency_histo" : {
+      "values" :  [0.1, 0.2, 0.3, 0.4, 0.5], <1>
+      "counts" : [8, 17, 8, 7, 6] <2>
+   }
+}
+
+POST /metrics_index/_search?size=0
+{
+  "aggs" : {
+    "min_latency" : { "min" : { "field" : "latency_histo" } }
+  }
+}
+--------------------------------------------------
+
+The `max` aggregation will return the maximum value of all histogram fields:
+
+[source,console-result]
+--------------------------------------------------
+{
+  ...
+  "aggregations": {
+    "min_latency": {
+      "value": 0.5
+    }
+  }
+}
+--------------------------------------------------
+// TESTRESPONSE[skip:test not setup]

docs/reference/aggregations/metrics/min-aggregation.asciidoc

@@ -140,3 +140,54 @@ POST /sales/_search
 
 <1> Documents without a value in the `grade` field will fall into the same
 bucket as documents that have the value `10`.
+
+[[search-aggregations-metrics-min-aggregation-histogram-fields]]
+==== Histogram fields
+
+When `min` is computed on <<histogram,histogram fields>>, the result of the aggregation is the minimum
+of all elements in the `values` array. Note, that the `counts` array of the histogram is ignored.
+
+For example, for the following index that stores pre-aggregated histograms with latency metrics for different networks:
+
+[source,console]
+--------------------------------------------------
+PUT metrics_index/_doc/1
+{
+  "network.name" : "net-1",
+  "latency_histo" : {
+      "values" : [0.1, 0.2, 0.3, 0.4, 0.5], <1>
+      "counts" : [3, 7, 23, 12, 6] <2>
+   }
+}
+
+PUT metrics_index/_doc/2
+{
+  "network.name" : "net-2",
+  "latency_histo" : {
+      "values" :  [0.1, 0.2, 0.3, 0.4, 0.5], <1>
+      "counts" : [8, 17, 8, 7, 6] <2>
+   }
+}
+
+POST /metrics_index/_search?size=0
+{
+  "aggs" : {
+    "min_latency" : { "min" : { "field" : "latency_histo" } }
+  }
+}
+--------------------------------------------------
+
+The `min` aggregation will return the minimum value of all histogram fields:
+
+[source,console-result]
+--------------------------------------------------
+{
+  ...
+  "aggregations": {
+    "min_latency": {
+      "value": 0.1
+    }
+  }
+}
+--------------------------------------------------
+// TESTRESPONSE[skip:test not setup]

docs/reference/mapping/types/histogram.asciidoc

@@ -35,6 +35,8 @@ binary <<doc-values,doc values>> and not indexed. Its size in bytes is at most
 Because the data is not indexed, you only can use `histogram` fields for the
 following aggregations and queries:
 
+* <<search-aggregations-metrics-min-aggregation-histogram-fields,min>> aggregation
+* <<search-aggregations-metrics-max-aggregation-histogram-fields,max>> aggregation
 * <<search-aggregations-metrics-sum-aggregation-histogram-fields,sum>> aggregation
 * <<search-aggregations-metrics-valuecount-aggregation-histogram-fields,value_count>> aggregation
 * <<search-aggregations-metrics-avg-aggregation-histogram-fields,avg>> aggregation

x-pack/plugin/analytics/src/main/java/org/elasticsearch/xpack/analytics/AnalyticsPlugin.java

@@ -150,14 +150,16 @@ public class AnalyticsPlugin extends Plugin implements SearchPlugin, ActionPlugi
 
     @Override
     public List<Consumer<ValuesSourceRegistry.Builder>> getAggregationExtentions() {
-            return List.of(
-                AnalyticsAggregatorFactory::registerPercentilesAggregator,
-                AnalyticsAggregatorFactory::registerPercentileRanksAggregator,
-                AnalyticsAggregatorFactory::registerHistoBackedSumAggregator,
-                AnalyticsAggregatorFactory::registerHistoBackedValueCountAggregator,
-                AnalyticsAggregatorFactory::registerHistoBackedAverageAggregator,
-                AnalyticsAggregatorFactory::registerHistoBackedHistogramAggregator
-            );
+        return List.of(
+            AnalyticsAggregatorFactory::registerPercentilesAggregator,
+            AnalyticsAggregatorFactory::registerPercentileRanksAggregator,
+            AnalyticsAggregatorFactory::registerHistoBackedSumAggregator,
+            AnalyticsAggregatorFactory::registerHistoBackedValueCountAggregator,
+            AnalyticsAggregatorFactory::registerHistoBackedAverageAggregator,
+            AnalyticsAggregatorFactory::registerHistoBackedHistogramAggregator,
+            AnalyticsAggregatorFactory::registerHistoBackedMinggregator,
+            AnalyticsAggregatorFactory::registerHistoBackedMaxggregator
+        );
     }
 
     @Override

x-pack/plugin/analytics/src/main/java/org/elasticsearch/xpack/analytics/aggregations/AnalyticsAggregatorFactory.java

@@ -7,6 +7,8 @@ package org.elasticsearch.xpack.analytics.aggregations;
 
 import org.elasticsearch.search.aggregations.bucket.histogram.HistogramAggregationBuilder;
 import org.elasticsearch.search.aggregations.metrics.AvgAggregationBuilder;
+import org.elasticsearch.search.aggregations.metrics.MaxAggregationBuilder;
+import org.elasticsearch.search.aggregations.metrics.MinAggregationBuilder;
 import org.elasticsearch.search.aggregations.metrics.PercentileRanksAggregationBuilder;
 import org.elasticsearch.search.aggregations.metrics.PercentilesAggregationBuilder;
 import org.elasticsearch.search.aggregations.metrics.PercentilesConfig;
@@ -18,6 +20,8 @@ import org.elasticsearch.xpack.analytics.aggregations.bucket.histogram.HistoBack
 import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedAvgAggregator;
 import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedHDRPercentileRanksAggregator;
 import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedHDRPercentilesAggregator;
+import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedMaxAggregator;
+import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedMinAggregator;
 import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedSumAggregator;
 import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedTDigestPercentileRanksAggregator;
 import org.elasticsearch.xpack.analytics.aggregations.metrics.HistoBackedTDigestPercentilesAggregator;
@@ -87,4 +91,13 @@ public class AnalyticsAggregatorFactory {
             HistoBackedHistogramAggregator::new,
                 true);
     }
+
+    public static void registerHistoBackedMinggregator(ValuesSourceRegistry.Builder builder) {
+        builder.register(MinAggregationBuilder.REGISTRY_KEY, AnalyticsValuesSourceType.HISTOGRAM, HistoBackedMinAggregator::new, true);
+    }
+
+    public static void registerHistoBackedMaxggregator(ValuesSourceRegistry.Builder builder) {
+        builder.register(MaxAggregationBuilder.REGISTRY_KEY, AnalyticsValuesSourceType.HISTOGRAM, HistoBackedMaxAggregator::new, true);
+    }
+
 }

x-pack/plugin/analytics/src/main/java/org/elasticsearch/xpack/analytics/aggregations/metrics/HistoBackedMaxAggregator.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.analytics.aggregations.metrics;
+
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.search.CollectionTerminatedException;
+import org.apache.lucene.search.ScoreMode;
+import org.elasticsearch.common.lease.Releasables;
+import org.elasticsearch.common.util.BigArrays;
+import org.elasticsearch.common.util.DoubleArray;
+import org.elasticsearch.index.fielddata.HistogramValue;
+import org.elasticsearch.index.fielddata.HistogramValues;
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.Aggregator;
+import org.elasticsearch.search.aggregations.InternalAggregation;
+import org.elasticsearch.search.aggregations.LeafBucketCollector;
+import org.elasticsearch.search.aggregations.LeafBucketCollectorBase;
+import org.elasticsearch.search.aggregations.metrics.InternalMax;
+import org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator;
+import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
+import org.elasticsearch.search.internal.SearchContext;
+import org.elasticsearch.xpack.analytics.aggregations.support.HistogramValuesSource;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class HistoBackedMaxAggregator extends NumericMetricsAggregator.SingleValue {
+
+    private final HistogramValuesSource.Histogram valuesSource;
+    final DocValueFormat formatter;
+    DoubleArray maxes;
+
+    public HistoBackedMaxAggregator(
+        String name,
+        ValuesSourceConfig config,
+        SearchContext context,
+        Aggregator parent,
+        Map<String, Object> metadata
+    ) throws IOException {
+        super(name, context, parent, metadata);
+        this.valuesSource = config.hasValues() ? (HistogramValuesSource.Histogram) config.getValuesSource() : null;
+        if (valuesSource != null) {
+            maxes = context.bigArrays().newDoubleArray(1, false);
+            maxes.fill(0, maxes.size(), Double.NEGATIVE_INFINITY);
+        }
+        this.formatter = config.format();
+    }
+
+    @Override
+    public ScoreMode scoreMode() {
+        return valuesSource != null && valuesSource.needsScores() ? ScoreMode.COMPLETE : ScoreMode.COMPLETE_NO_SCORES;
+    }
+
+    @Override
+    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBucketCollector sub) throws IOException {
+        if (valuesSource == null) {
+            if (parent != null) {
+                return LeafBucketCollector.NO_OP_COLLECTOR;
+            } else {
+                // we have no parent and the values source is empty so we can skip collecting hits.
+                throw new CollectionTerminatedException();
+            }
+        }
+
+        final BigArrays bigArrays = context.bigArrays();
+        final HistogramValues values = valuesSource.getHistogramValues(ctx);
+        return new LeafBucketCollectorBase(sub, values) {
+
+            @Override
+            public void collect(int doc, long bucket) throws IOException {
+                if (bucket >= maxes.size()) {
+                    long from = maxes.size();
+                    maxes = bigArrays.grow(maxes, bucket + 1);
+                    maxes.fill(from, maxes.size(), Double.NEGATIVE_INFINITY);
+                }
+                if (values.advanceExact(doc)) {
+                    final HistogramValue sketch = values.histogram();
+                    while (sketch.next()) {
+                        double value = sketch.value();
+                        double max = maxes.get(bucket);
+                        max = Math.max(max, value);
+                        maxes.set(bucket, max);
+                    }
+                }
+            }
+        };
+    }
+
+    @Override
+    public double metric(long owningBucketOrd) {
+        if (valuesSource == null || owningBucketOrd >= maxes.size()) {
+            return Double.NEGATIVE_INFINITY;
+        }
+        return maxes.get(owningBucketOrd);
+    }
+
+    @Override
+    public InternalAggregation buildAggregation(long bucket) {
+        if (valuesSource == null || bucket >= maxes.size()) {
+            return buildEmptyAggregation();
+        }
+        return new InternalMax(name, maxes.get(bucket), formatter, metadata());
+    }
+
+    @Override
+    public InternalAggregation buildEmptyAggregation() {
+        return new InternalMax(name, Double.NEGATIVE_INFINITY, formatter, metadata());
+    }
+
+    @Override
+    public void doClose() {
+        Releasables.close(maxes);
+    }
+}

x-pack/plugin/analytics/src/main/java/org/elasticsearch/xpack/analytics/aggregations/metrics/HistoBackedMinAggregator.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.analytics.aggregations.metrics;
+
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.search.CollectionTerminatedException;
+import org.apache.lucene.search.ScoreMode;
+import org.elasticsearch.common.lease.Releasables;
+import org.elasticsearch.common.util.BigArrays;
+import org.elasticsearch.common.util.DoubleArray;
+import org.elasticsearch.index.fielddata.HistogramValue;
+import org.elasticsearch.index.fielddata.HistogramValues;
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.Aggregator;
+import org.elasticsearch.search.aggregations.InternalAggregation;
+import org.elasticsearch.search.aggregations.LeafBucketCollector;
+import org.elasticsearch.search.aggregations.LeafBucketCollectorBase;
+import org.elasticsearch.search.aggregations.metrics.InternalMin;
+import org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator;
+import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
+import org.elasticsearch.search.internal.SearchContext;
+import org.elasticsearch.xpack.analytics.aggregations.support.HistogramValuesSource;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class HistoBackedMinAggregator extends NumericMetricsAggregator.SingleValue {
+
+    private final HistogramValuesSource.Histogram valuesSource;
+    final DocValueFormat format;
+    DoubleArray mins;
+
+    public HistoBackedMinAggregator(
+        String name,
+        ValuesSourceConfig config,
+        SearchContext context,
+        Aggregator parent,
+        Map<String, Object> metadata
+    ) throws IOException {
+        super(name, context, parent, metadata);
+        this.valuesSource = config.hasValues() ? (HistogramValuesSource.Histogram) config.getValuesSource() : null;
+        if (valuesSource != null) {
+            mins = context.bigArrays().newDoubleArray(1, false);
+            mins.fill(0, mins.size(), Double.POSITIVE_INFINITY);
+        }
+        this.format = config.format();
+    }
+
+    @Override
+    public ScoreMode scoreMode() {
+        return valuesSource != null && valuesSource.needsScores() ? ScoreMode.COMPLETE : ScoreMode.COMPLETE_NO_SCORES;
+    }
+
+    @Override
+    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBucketCollector sub) throws IOException {
+        if (valuesSource == null) {
+            if (parent == null) {
+                return LeafBucketCollector.NO_OP_COLLECTOR;
+            } else {
+                // we have no parent and the values source is empty so we can skip collecting hits.
+                throw new CollectionTerminatedException();
+            }
+        }
+
+        final BigArrays bigArrays = context.bigArrays();
+        final HistogramValues values = valuesSource.getHistogramValues(ctx);
+        return new LeafBucketCollectorBase(sub, values) {
+
+            @Override
+            public void collect(int doc, long bucket) throws IOException {
+                if (bucket >= mins.size()) {
+                    long from = mins.size();
+                    mins = bigArrays.grow(mins, bucket + 1);
+                    mins.fill(from, mins.size(), Double.POSITIVE_INFINITY);
+                }
+
+                if (values.advanceExact(doc)) {
+                    final HistogramValue sketch = values.histogram();
+                    while (sketch.next()) {
+                        double value = sketch.value();
+                        double min = mins.get(bucket);
+                        min = Math.min(min, value);
+                        mins.set(bucket, min);
+                    }
+                }
+
+            }
+        };
+    }
+
+    @Override
+    public double metric(long owningBucketOrd) {
+        if (valuesSource == null || owningBucketOrd >= mins.size()) {
+            return Double.POSITIVE_INFINITY;
+        }
+        return mins.get(owningBucketOrd);
+    }
+
+    @Override
+    public InternalAggregation buildAggregation(long bucket) {
+        if (valuesSource == null || bucket >= mins.size()) {
+            return buildEmptyAggregation();
+        }
+        return new InternalMin(name, mins.get(bucket), format, metadata());
+    }
+
+    @Override
+    public InternalAggregation buildEmptyAggregation() {
+        return new InternalMin(name, Double.POSITIVE_INFINITY, format, metadata());
+    }
+
+    @Override
+    public void doClose() {
+        Releasables.close(mins);
+    }
+}

x-pack/plugin/analytics/src/test/java/org/elasticsearch/xpack/analytics/aggregations/metrics/HistoBackedMaxAggregatorTests.java

@@ -0,0 +1,154 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.analytics.aggregations.metrics;
+
+import com.tdunning.math.stats.Centroid;
+import com.tdunning.math.stats.TDigest;
+import org.apache.lucene.document.BinaryDocValuesField;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.TermQuery;
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.plugins.SearchPlugin;
+import org.elasticsearch.search.aggregations.AggregationBuilder;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.metrics.InternalMax;
+import org.elasticsearch.search.aggregations.metrics.MaxAggregationBuilder;
+import org.elasticsearch.search.aggregations.metrics.TDigestState;
+import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
+import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
+import org.elasticsearch.search.aggregations.support.ValuesSourceType;
+import org.elasticsearch.xpack.analytics.AnalyticsPlugin;
+import org.elasticsearch.xpack.analytics.aggregations.support.AnalyticsValuesSourceType;
+import org.elasticsearch.xpack.analytics.mapper.HistogramFieldMapper;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.function.Consumer;
+
+import static java.util.Collections.singleton;
+import static org.elasticsearch.search.aggregations.AggregationBuilders.max;
+
+public class HistoBackedMaxAggregatorTests extends AggregatorTestCase {
+
+    private static final String FIELD_NAME = "field";
+
+    public void testNoDocs() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            // Intentionally not writing any docs
+        }, max -> {
+            assertEquals(Double.NEGATIVE_INFINITY, max.getValue(), 0d);
+            assertFalse(AggregationInspectionHelper.hasValue(max));
+        });
+    }
+
+    public void testNoMatchingField() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            iw.addDocument(singleton(getDocValue("wrong_field", new double[] {3, 1.2, 10})));
+            iw.addDocument(singleton(getDocValue("wrong_field", new double[] {5.3, 6, 20})));
+        }, max -> {
+            assertEquals(Double.NEGATIVE_INFINITY, max.getValue(), 0d);
+            assertFalse(AggregationInspectionHelper.hasValue(max));
+        });
+    }
+
+    public void testSimpleHistogram() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            iw.addDocument(singleton(getDocValue(FIELD_NAME, new double[] {3, 1.2, 10})));
+            iw.addDocument(singleton(getDocValue(FIELD_NAME, new double[] {5.3, 6, 6, 20})));
+            iw.addDocument(singleton(getDocValue(FIELD_NAME, new double[] {-10, 0.01, 1, 90})));
+        }, max -> {
+            assertEquals(90d, max.getValue(), 0.01d);
+            assertTrue(AggregationInspectionHelper.hasValue(max));
+        });
+    }
+
+    public void testQueryFiltering() throws IOException {
+        testCase(new TermQuery(new Term("match", "yes")), iw -> {
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "yes", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {3, 1.2, 10}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "yes", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {5.3, 6, 20}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "no", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {-34, 1.2, 10}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "no", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {3, 1.2, 100}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "yes", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {-10, 0.01, 1, 90}))
+            );
+        }, min -> {
+            assertEquals(90d, min.getValue(), 0.01d);
+            assertTrue(AggregationInspectionHelper.hasValue(min));
+        });
+    }
+
+    private void testCase(Query query,
+                          CheckedConsumer<RandomIndexWriter, IOException> indexer,
+                          Consumer<InternalMax> verify) throws IOException {
+        testCase(max("_name").field(FIELD_NAME), query, indexer, verify, defaultFieldType());
+    }
+
+    private BinaryDocValuesField getDocValue(String fieldName, double[] values) throws IOException {
+        TDigest histogram = new TDigestState(100.0); //default
+        for (double value : values) {
+            histogram.add(value);
+        }
+        BytesStreamOutput streamOutput = new BytesStreamOutput();
+        histogram.compress();
+        Collection<Centroid> centroids = histogram.centroids();
+        Iterator<Centroid> iterator = centroids.iterator();
+        while ( iterator.hasNext()) {
+            Centroid centroid = iterator.next();
+            streamOutput.writeVInt(centroid.count());
+            streamOutput.writeDouble(centroid.mean());
+        }
+        return new BinaryDocValuesField(fieldName, streamOutput.bytes().toBytesRef());
+    }
+
+    @Override
+    protected List<SearchPlugin> getSearchPlugins() {
+        return List.of(new AnalyticsPlugin());
+    }
+
+    @Override
+    protected List<ValuesSourceType> getSupportedValuesSourceTypes() {
+        // Note: this is the same list as Core, plus Analytics
+        return List.of(
+            CoreValuesSourceType.NUMERIC,
+            CoreValuesSourceType.BOOLEAN,
+            CoreValuesSourceType.DATE,
+            AnalyticsValuesSourceType.HISTOGRAM
+        );
+    }
+
+    @Override
+    protected AggregationBuilder createAggBuilderForTypeTest(MappedFieldType fieldType, String fieldName) {
+        return new MaxAggregationBuilder("_name").field(fieldName);
+    }
+
+    private MappedFieldType defaultFieldType() {
+        return new HistogramFieldMapper.HistogramFieldType(HistoBackedMaxAggregatorTests.FIELD_NAME, true, Collections.emptyMap());
+    }
+}

x-pack/plugin/analytics/src/test/java/org/elasticsearch/xpack/analytics/aggregations/metrics/HistoBackedMinAggregatorTests.java

@@ -0,0 +1,154 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.analytics.aggregations.metrics;
+
+import com.tdunning.math.stats.Centroid;
+import com.tdunning.math.stats.TDigest;
+import org.apache.lucene.document.BinaryDocValuesField;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.StringField;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.TermQuery;
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.plugins.SearchPlugin;
+import org.elasticsearch.search.aggregations.AggregationBuilder;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.metrics.InternalMin;
+import org.elasticsearch.search.aggregations.metrics.MinAggregationBuilder;
+import org.elasticsearch.search.aggregations.metrics.TDigestState;
+import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
+import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
+import org.elasticsearch.search.aggregations.support.ValuesSourceType;
+import org.elasticsearch.xpack.analytics.AnalyticsPlugin;
+import org.elasticsearch.xpack.analytics.aggregations.support.AnalyticsValuesSourceType;
+import org.elasticsearch.xpack.analytics.mapper.HistogramFieldMapper;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.function.Consumer;
+
+import static java.util.Collections.singleton;
+import static org.elasticsearch.search.aggregations.AggregationBuilders.min;
+
+public class HistoBackedMinAggregatorTests extends AggregatorTestCase {
+
+    private static final String FIELD_NAME = "field";
+
+    public void testNoDocs() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            // Intentionally not writing any docs
+        }, min -> {
+            assertEquals(Double.POSITIVE_INFINITY, min.getValue(), 0d);
+            assertFalse(AggregationInspectionHelper.hasValue(min));
+        });
+    }
+
+    public void testNoMatchingField() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            iw.addDocument(singleton(getDocValue("wrong_field", new double[] {3, 1.2, 10})));
+            iw.addDocument(singleton(getDocValue("wrong_field", new double[] {5.3, 6, 20})));
+        }, min -> {
+            assertEquals(Double.POSITIVE_INFINITY, min.getValue(), 0d);
+            assertFalse(AggregationInspectionHelper.hasValue(min));
+        });
+    }
+
+    public void testSimpleHistogram() throws IOException {
+        testCase(new MatchAllDocsQuery(), iw -> {
+            iw.addDocument(singleton(getDocValue(FIELD_NAME, new double[] {3, 1.2, 10})));
+            iw.addDocument(singleton(getDocValue(FIELD_NAME, new double[] {5.3, 6, 6, 20})));
+            iw.addDocument(singleton(getDocValue(FIELD_NAME, new double[] {-10, 0.01, 1, 90})));
+        }, min -> {
+            assertEquals(-10d, min.getValue(), 0.01d);
+            assertTrue(AggregationInspectionHelper.hasValue(min));
+        });
+    }
+
+    public void testQueryFiltering() throws IOException {
+        testCase(new TermQuery(new Term("match", "yes")), iw -> {
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "yes", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {3, 1.2, 10}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "yes", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {5.3, 6, 20}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "no", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {-34, 1.2, 10}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "no", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {3, 1.2, 10}))
+            );
+            iw.addDocument(Arrays.asList(
+                new StringField("match", "yes", Field.Store.NO),
+                getDocValue(FIELD_NAME, new double[] {-10, 0.01, 1, 90}))
+            );
+        }, min -> {
+            assertEquals(-10d, min.getValue(), 0.01d);
+            assertTrue(AggregationInspectionHelper.hasValue(min));
+        });
+    }
+
+    private void testCase(Query query,
+                          CheckedConsumer<RandomIndexWriter, IOException> indexer,
+                          Consumer<InternalMin> verify) throws IOException {
+        testCase(min("_name").field(FIELD_NAME), query, indexer, verify, defaultFieldType());
+    }
+
+    private BinaryDocValuesField getDocValue(String fieldName, double[] values) throws IOException {
+        TDigest histogram = new TDigestState(100.0); //default
+        for (double value : values) {
+            histogram.add(value);
+        }
+        BytesStreamOutput streamOutput = new BytesStreamOutput();
+        histogram.compress();
+        Collection<Centroid> centroids = histogram.centroids();
+        Iterator<Centroid> iterator = centroids.iterator();
+        while ( iterator.hasNext()) {
+            Centroid centroid = iterator.next();
+            streamOutput.writeVInt(centroid.count());
+            streamOutput.writeDouble(centroid.mean());
+        }
+        return new BinaryDocValuesField(fieldName, streamOutput.bytes().toBytesRef());
+    }
+
+    @Override
+    protected List<SearchPlugin> getSearchPlugins() {
+        return List.of(new AnalyticsPlugin());
+    }
+
+    @Override
+    protected List<ValuesSourceType> getSupportedValuesSourceTypes() {
+        // Note: this is the same list as Core, plus Analytics
+        return List.of(
+            CoreValuesSourceType.NUMERIC,
+            CoreValuesSourceType.BOOLEAN,
+            CoreValuesSourceType.DATE,
+            AnalyticsValuesSourceType.HISTOGRAM
+        );
+    }
+
+    @Override
+    protected AggregationBuilder createAggBuilderForTypeTest(MappedFieldType fieldType, String fieldName) {
+        return new MinAggregationBuilder("_name").field(fieldName);
+    }
+
+    private MappedFieldType defaultFieldType() {
+        return new HistogramFieldMapper.HistogramFieldType(HistoBackedMinAggregatorTests.FIELD_NAME, true, Collections.emptyMap());
+    }
+}

x-pack/plugin/src/test/resources/rest-api-spec/test/analytics/histogram.yml

@@ -39,11 +39,19 @@ setup:
             histo_avg:
               avg:
                 field: "latency"
+            histo_min:
+              min:
+                field: "latency"
+            histo_max:
+              max:
+                field: "latency"
 
   - match: { hits.total.value: 2 }
   - match: { aggregations.histo_sum.value: 25 }
   - match: { aggregations.histo_value_count.value: 80 }
   - match: { aggregations.histo_avg.value:  0.3125}
+  - match: { aggregations.histo_min.value:  0}
+  - match: { aggregations.histo_max.value:  0.5}
 
 
 ---