Save memory when histogram agg is not on top (backport of #57277) (#57377)

This saves some memory when the `histogram` aggregation is not a top
level aggregation by dropping `asMultiBucketAggregator` in favor of
natively implementing multi-bucket storage in the aggregator. For the
most part this just uses the `LongKeyedBucketOrds` that we built the
first time we did this.

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/10_histogram.yml

@@ -492,7 +492,65 @@ setup:
   - match: { aggregations.histo.buckets.0.doc_count: 1 }
 
 ---
-"profiler":
+"histogram profiler":
+  - skip:
+      version: " - 7.8.99"
+      reason:  debug info added in 7.9.0
+
+  - do:
+      indices.create:
+          index: test_2
+          body:
+            settings:
+              number_of_replicas: 0
+              number_of_shards: 1
+            mappings:
+              properties:
+                n:
+                  type: long
+
+  - do:
+      bulk:
+        index: test_2
+        refresh: true
+        body:
+            - '{"index": {}}'
+            - '{"n": "1"}'
+            - '{"index": {}}'
+            - '{"n": "2"}'
+            - '{"index": {}}'
+            - '{"n": "10"}'
+            - '{"index": {}}'
+            - '{"n": "17"}'
+
+  - do:
+      search:
+        index: test_2
+        body:
+          size: 0
+          profile: true
+          aggs:
+            histo:
+              histogram:
+                field: n
+                interval: 5
+  - match: { hits.total.value: 4 }
+  - length: { aggregations.histo.buckets: 4 }
+  - match: { aggregations.histo.buckets.0.key: 0 }
+  - match: { aggregations.histo.buckets.0.doc_count: 2 }
+  - match: { aggregations.histo.buckets.1.key: 5 }
+  - match: { aggregations.histo.buckets.1.doc_count: 0 }
+  - match: { aggregations.histo.buckets.2.key: 10 }
+  - match: { aggregations.histo.buckets.2.doc_count: 1 }
+  - match: { aggregations.histo.buckets.3.key: 15 }
+  - match: { aggregations.histo.buckets.3.doc_count: 1 }
+  - match: { profile.shards.0.aggregations.0.type: NumericHistogramAggregator }
+  - match: { profile.shards.0.aggregations.0.description: histo }
+  - match: { profile.shards.0.aggregations.0.breakdown.collect_count: 4 }
+  - match: { profile.shards.0.aggregations.0.debug.total_buckets: 3 }
+
+---
+"date_histogram profiler":
   - skip:
       version: " - 7.8.99"
       reason:  debug info added in 7.9.0

server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/AbstractHistogramAggregator.java

@@ -0,0 +1,124 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.search.aggregations.bucket.histogram;
+
+import org.apache.lucene.util.CollectionUtil;
+import org.elasticsearch.common.lease.Releasables;
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.Aggregator;
+import org.elasticsearch.search.aggregations.AggregatorFactories;
+import org.elasticsearch.search.aggregations.BucketOrder;
+import org.elasticsearch.search.aggregations.InternalAggregation;
+import org.elasticsearch.search.aggregations.bucket.BucketsAggregator;
+import org.elasticsearch.search.aggregations.bucket.histogram.InternalHistogram.EmptyBucketInfo;
+import org.elasticsearch.search.aggregations.bucket.terms.LongKeyedBucketOrds;
+import org.elasticsearch.search.internal.SearchContext;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.Map;
+import java.util.function.BiConsumer;
+
+/**
+ * Base class for functionality shared between aggregators for this
+ * {@code histogram} aggregation.
+ */
+public abstract class AbstractHistogramAggregator extends BucketsAggregator {
+    protected final DocValueFormat formatter;
+    protected final double interval;
+    protected final double offset;
+    protected final BucketOrder order;
+    protected final boolean keyed;
+    protected final long minDocCount;
+    protected final double minBound;
+    protected final double maxBound;
+    protected final LongKeyedBucketOrds bucketOrds;
+
+    public AbstractHistogramAggregator(
+        String name,
+        AggregatorFactories factories,
+        double interval,
+        double offset,
+        BucketOrder order,
+        boolean keyed,
+        long minDocCount,
+        double minBound,
+        double maxBound,
+        DocValueFormat formatter,
+        SearchContext context,
+        Aggregator parent,
+        boolean collectsFromSingleBucket,
+        Map<String, Object> metadata
+    ) throws IOException {
+        super(name, factories, context, parent, metadata);
+        if (interval <= 0) {
+            throw new IllegalArgumentException("interval must be positive, got: " + interval);
+        }
+        this.interval = interval;
+        this.offset = offset;
+        this.order = order;
+        order.validate(this);
+        this.keyed = keyed;
+        this.minDocCount = minDocCount;
+        this.minBound = minBound;
+        this.maxBound = maxBound;
+        this.formatter = formatter;
+        bucketOrds = LongKeyedBucketOrds.build(context.bigArrays(), collectsFromSingleBucket);
+    }
+
+    @Override
+    public InternalAggregation[] buildAggregations(long[] owningBucketOrds) throws IOException {
+        return buildAggregationsForVariableBuckets(owningBucketOrds, bucketOrds,
+            (bucketValue, docCount, subAggregationResults) -> {
+                double roundKey = Double.longBitsToDouble(bucketValue);
+                double key = roundKey * interval + offset;
+                return new InternalHistogram.Bucket(key, docCount, keyed, formatter, subAggregationResults);
+            }, buckets -> {
+                // the contract of the histogram aggregation is that shards must return buckets ordered by key in ascending order
+                CollectionUtil.introSort(buckets, BucketOrder.key(true).comparator());
+
+                EmptyBucketInfo emptyBucketInfo = null;
+                if (minDocCount == 0) {
+                    emptyBucketInfo = new EmptyBucketInfo(interval, offset, minBound, maxBound, buildEmptySubAggregations());
+                }
+                return new InternalHistogram(name, buckets, order, minDocCount, emptyBucketInfo, formatter, keyed, metadata());
+            });
+    }
+
+    @Override
+    public InternalAggregation buildEmptyAggregation() {
+        InternalHistogram.EmptyBucketInfo emptyBucketInfo = null;
+        if (minDocCount == 0) {
+            emptyBucketInfo = new InternalHistogram.EmptyBucketInfo(interval, offset, minBound, maxBound, buildEmptySubAggregations());
+        }
+        return new InternalHistogram(name, Collections.emptyList(), order, minDocCount, emptyBucketInfo, formatter, keyed, metadata());
+    }
+
+    @Override
+    public void doClose() {
+        Releasables.close(bucketOrds);
+    }
+
+    @Override
+    public void collectDebugInfo(BiConsumer<String, Object> add) {
+        add.accept("total_buckets", bucketOrds.size());
+        super.collectDebugInfo(add);
+    }
+}

server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/HistogramAggregatorFactory.java

@@ -19,8 +19,8 @@
 
 package org.elasticsearch.search.aggregations.bucket.histogram;
 
+import org.elasticsearch.common.collect.List;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.AggregationExecutionException;
 import org.elasticsearch.search.aggregations.Aggregator;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
@@ -36,8 +36,6 @@ import org.elasticsearch.search.aggregations.support.ValuesSourceRegistry;
 import org.elasticsearch.search.internal.SearchContext;
 
 import java.io.IOException;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.Map;
 
 /**
@@ -54,40 +52,11 @@ public final class HistogramAggregatorFactory extends ValuesSourceAggregatorFact
 
     static void registerAggregators(ValuesSourceRegistry.Builder builder) {
         builder.register(HistogramAggregationBuilder.NAME, CoreValuesSourceType.RANGE,
-            new HistogramAggregatorSupplier() {
+            (HistogramAggregatorSupplier) RangeHistogramAggregator::new);
-                @Override
-                public Aggregator build(String name, AggregatorFactories factories, double interval, double offset,
-                                        BucketOrder order, boolean keyed, long minDocCount, double minBound, double maxBound,
-                                        ValuesSource valuesSource, DocValueFormat formatter, SearchContext context,
-                                        Aggregator parent,
-                                        Map<String, Object> metadata) throws IOException {
-                    ValuesSource.Range rangeValueSource = (ValuesSource.Range) valuesSource;
-                    if (rangeValueSource.rangeType().isNumeric() == false) {
-                        throw new IllegalArgumentException("Expected numeric range type but found non-numeric range ["
-                            + rangeValueSource.rangeType().name + "]");
-                    }
-                    return new RangeHistogramAggregator(name, factories, interval, offset, order, keyed, minDocCount, minBound,
-                        maxBound, rangeValueSource, formatter, context, parent, metadata);
-                }
-            }
-        );
 
         builder.register(HistogramAggregationBuilder.NAME,
-            Collections.unmodifiableList(Arrays.asList(CoreValuesSourceType.NUMERIC,
+            List.of(CoreValuesSourceType.NUMERIC, CoreValuesSourceType.DATE, CoreValuesSourceType.BOOLEAN),
-                                                       CoreValuesSourceType.DATE,
+            (HistogramAggregatorSupplier) NumericHistogramAggregator::new);
-                                                       CoreValuesSourceType.BOOLEAN)),
-            new HistogramAggregatorSupplier() {
-                @Override
-                public Aggregator build(String name, AggregatorFactories factories, double interval, double offset,
-                                        BucketOrder order, boolean keyed, long minDocCount, double minBound, double maxBound,
-                                        ValuesSource valuesSource, DocValueFormat formatter, SearchContext context,
-                                        Aggregator parent,
-                                        Map<String, Object> metadata) throws IOException {
-                    return new NumericHistogramAggregator(name, factories, interval, offset, order, keyed, minDocCount, minBound,
-                        maxBound, (ValuesSource.Numeric) valuesSource, formatter, context, parent, metadata);
-                }
-            }
-        );
     }
 
     public HistogramAggregatorFactory(String name,
@@ -123,10 +92,6 @@ public final class HistogramAggregatorFactory extends ValuesSourceAggregatorFact
                                             Aggregator parent,
                                             boolean collectsFromSingleBucket,
                                             Map<String, Object> metadata) throws IOException {
-        if (collectsFromSingleBucket == false) {
-            return asMultiBucketAggregator(this, searchContext, parent);
-        }
-
         AggregatorSupplier aggregatorSupplier = queryShardContext.getValuesSourceRegistry().getAggregator(config.valueSourceType(),
             HistogramAggregationBuilder.NAME);
         if (aggregatorSupplier instanceof HistogramAggregatorSupplier == false) {
@@ -135,7 +100,7 @@ public final class HistogramAggregatorFactory extends ValuesSourceAggregatorFact
         }
         HistogramAggregatorSupplier histogramAggregatorSupplier = (HistogramAggregatorSupplier) aggregatorSupplier;
         return histogramAggregatorSupplier.build(name, factories, interval, offset, order, keyed, minDocCount, minBound, maxBound,
-                valuesSource, config.format(), searchContext, parent, metadata);
+                valuesSource, config.format(), searchContext, parent, collectsFromSingleBucket, metadata);
     }
 
     @Override
@@ -143,6 +108,6 @@ public final class HistogramAggregatorFactory extends ValuesSourceAggregatorFact
                                             Aggregator parent,
                                             Map<String, Object> metadata) throws IOException {
         return new NumericHistogramAggregator(name, factories, interval, offset, order, keyed, minDocCount, minBound, maxBound,
-            null, config.format(), searchContext, parent, metadata);
+            null, config.format(), searchContext, parent, false, metadata);
     }
 }

server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/NumericHistogramAggregator.java

@@ -21,27 +21,19 @@ package org.elasticsearch.search.aggregations.bucket.histogram;
 
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.ScoreMode;
-import org.apache.lucene.util.CollectionUtil;
 import org.elasticsearch.common.Nullable;
-import org.elasticsearch.common.lease.Releasables;
-import org.elasticsearch.common.util.LongHash;
 import org.elasticsearch.index.fielddata.SortedNumericDoubleValues;
 import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.Aggregator;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
 import org.elasticsearch.search.aggregations.BucketOrder;
-import org.elasticsearch.search.aggregations.InternalAggregation;
 import org.elasticsearch.search.aggregations.LeafBucketCollector;
 import org.elasticsearch.search.aggregations.LeafBucketCollectorBase;
-import org.elasticsearch.search.aggregations.bucket.BucketsAggregator;
-import org.elasticsearch.search.aggregations.bucket.histogram.InternalHistogram.EmptyBucketInfo;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
 import org.elasticsearch.search.internal.SearchContext;
 
 import java.io.IOException;
-import java.util.Collections;
 import java.util.Map;
-import java.util.function.BiConsumer;
 
 /**
  * An aggregator for numeric values. For a given {@code interval},
@@ -49,39 +41,43 @@ import java.util.function.BiConsumer;
  * written as {@code interval * x + offset} and yet is less than or equal to
  * {@code value}.
  */
-public class NumericHistogramAggregator extends BucketsAggregator {
+public class NumericHistogramAggregator extends AbstractHistogramAggregator {
-
     private final ValuesSource.Numeric valuesSource;
-    private final DocValueFormat formatter;
-    private final double interval, offset;
-    private final BucketOrder order;
-    private final boolean keyed;
-    private final long minDocCount;
-    private final double minBound, maxBound;
 
-    private final LongHash bucketOrds;
+    public NumericHistogramAggregator(
-
+        String name,
-    public NumericHistogramAggregator(String name, AggregatorFactories factories, double interval, double offset,
+        AggregatorFactories factories,
-                               BucketOrder order, boolean keyed, long minDocCount, double minBound, double maxBound,
+        double interval,
-                               @Nullable ValuesSource.Numeric valuesSource, DocValueFormat formatter,
+        double offset,
-                               SearchContext context, Aggregator parent, Map<String, Object> metadata) throws IOException {
+        BucketOrder order,
-
+        boolean keyed,
-        super(name, factories, context, parent, metadata);
+        long minDocCount,
-        if (interval <= 0) {
+        double minBound,
-            throw new IllegalArgumentException("interval must be positive, got: " + interval);
+        double maxBound,
-        }
+        @Nullable ValuesSource valuesSource,
-        this.interval = interval;
+        DocValueFormat formatter,
-        this.offset = offset;
+        SearchContext context,
-        this.order = order;
+        Aggregator parent,
-        order.validate(this);
+        boolean collectsFromSingleBucket,
-        this.keyed = keyed;
+        Map<String, Object> metadata
-        this.minDocCount = minDocCount;
+    ) throws IOException {
-        this.minBound = minBound;
+        super(
-        this.maxBound = maxBound;
+            name,
-        this.valuesSource = valuesSource;
+            factories,
-        this.formatter = formatter;
+            interval,
-
+            offset,
-        bucketOrds = new LongHash(1, context.bigArrays());
+            order,
+            keyed,
+            minDocCount,
+            minBound,
+            maxBound,
+            formatter,
+            context,
+            parent,
+            collectsFromSingleBucket,
+            metadata
+        );
+        this.valuesSource = (ValuesSource.Numeric) valuesSource;
     }
 
     @Override
@@ -102,8 +98,7 @@ public class NumericHistogramAggregator extends BucketsAggregator {
         final SortedNumericDoubleValues values = valuesSource.doubleValues(ctx);
         return new LeafBucketCollectorBase(sub, values) {
             @Override
-            public void collect(int doc, long bucket) throws IOException {
+            public void collect(int doc, long owningBucketOrd) throws IOException {
-                assert bucket == 0;
                 if (values.advanceExact(doc)) {
                     final int valuesCount = values.docValueCount();
 
@@ -115,7 +110,7 @@ public class NumericHistogramAggregator extends BucketsAggregator {
                         if (key == previousKey) {
                             continue;
                         }
-                        long bucketOrd = bucketOrds.add(Double.doubleToLongBits(key));
+                        long bucketOrd = bucketOrds.add(owningBucketOrd, Double.doubleToLongBits(key));
                         if (bucketOrd < 0) { // already seen
                             bucketOrd = -1 - bucketOrd;
                             collectExistingBucket(sub, doc, bucketOrd);
@@ -128,43 +123,4 @@ public class NumericHistogramAggregator extends BucketsAggregator {
             }
         };
     }
-
-    @Override
-    public InternalAggregation[] buildAggregations(long[] owningBucketOrds) throws IOException {
-        return buildAggregationsForVariableBuckets(owningBucketOrds, bucketOrds,
-            (bucketValue, docCount, subAggregationResults) -> {
-                double roundKey = Double.longBitsToDouble(bucketValue);
-                double key = roundKey * interval + offset;
-                return new InternalHistogram.Bucket(key, docCount, keyed, formatter, subAggregationResults);
-            }, buckets -> {
-                // the contract of the histogram aggregation is that shards must return buckets ordered by key in ascending order
-                CollectionUtil.introSort(buckets, BucketOrder.key(true).comparator());
-
-                EmptyBucketInfo emptyBucketInfo = null;
-                if (minDocCount == 0) {
-                    emptyBucketInfo = new EmptyBucketInfo(interval, offset, minBound, maxBound, buildEmptySubAggregations());
-                }
-                return new InternalHistogram(name, buckets, order, minDocCount, emptyBucketInfo, formatter, keyed, metadata());
-            });
-    }
-
-    @Override
-    public InternalAggregation buildEmptyAggregation() {
-        EmptyBucketInfo emptyBucketInfo = null;
-        if (minDocCount == 0) {
-            emptyBucketInfo = new EmptyBucketInfo(interval, offset, minBound, maxBound, buildEmptySubAggregations());
-        }
-        return new InternalHistogram(name, Collections.emptyList(), order, minDocCount, emptyBucketInfo, formatter, keyed, metadata());
-    }
-
-    @Override
-    public void doClose() {
-        Releasables.close(bucketOrds);
-    }
-
-    @Override
-    public void collectDebugInfo(BiConsumer<String, Object> add) {
-        add.accept("total_buckets", bucketOrds.size());
-        super.collectDebugInfo(add);
-    }
 }

server/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/RangeHistogramAggregator.java

@@ -21,10 +21,7 @@ package org.elasticsearch.search.aggregations.bucket.histogram;
 
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.util.BytesRef;
-import org.apache.lucene.util.CollectionUtil;
 import org.elasticsearch.common.Nullable;
-import org.elasticsearch.common.lease.Releasables;
-import org.elasticsearch.common.util.LongHash;
 import org.elasticsearch.index.fielddata.SortedBinaryDocValues;
 import org.elasticsearch.index.mapper.RangeFieldMapper;
 import org.elasticsearch.index.mapper.RangeType;
@@ -32,51 +29,57 @@ import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.Aggregator;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
 import org.elasticsearch.search.aggregations.BucketOrder;
-import org.elasticsearch.search.aggregations.InternalAggregation;
 import org.elasticsearch.search.aggregations.LeafBucketCollector;
 import org.elasticsearch.search.aggregations.LeafBucketCollectorBase;
-import org.elasticsearch.search.aggregations.bucket.BucketsAggregator;
-import org.elasticsearch.search.aggregations.bucket.histogram.InternalHistogram.EmptyBucketInfo;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
 import org.elasticsearch.search.internal.SearchContext;
 
 import java.io.IOException;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
-public class RangeHistogramAggregator extends BucketsAggregator {
+public class RangeHistogramAggregator extends AbstractHistogramAggregator {
     private final ValuesSource.Range valuesSource;
-    private final DocValueFormat formatter;
-    private final double interval, offset;
-    private final BucketOrder order;
-    private final boolean keyed;
-    private final long minDocCount;
-    private final double minBound, maxBound;
 
-    private final LongHash bucketOrds;
+    public RangeHistogramAggregator(
-
+        String name,
-    public RangeHistogramAggregator(String name, AggregatorFactories factories, double interval, double offset,
+        AggregatorFactories factories,
-                             BucketOrder order, boolean keyed, long minDocCount, double minBound, double maxBound,
+        double interval,
-                             @Nullable ValuesSource.Range valuesSource, DocValueFormat formatter,
+        double offset,
-                             SearchContext context, Aggregator parent, Map<String, Object> metadata) throws IOException {
+        BucketOrder order,
-
+        boolean keyed,
-        super(name, factories, context, parent, metadata);
+        long minDocCount,
-        if (interval <= 0) {
+        double minBound,
-            throw new IllegalArgumentException("interval must be positive, got: " + interval);
+        double maxBound,
+        @Nullable ValuesSource valuesSource,
+        DocValueFormat formatter,
+        SearchContext context,
+        Aggregator parent,
+        boolean collectsFromSingleBucket,
+        Map<String, Object> metadata
+    ) throws IOException {
+        super(
+            name,
+            factories,
+            interval,
+            offset,
+            order,
+            keyed,
+            minDocCount,
+            minBound,
+            maxBound,
+            formatter,
+            context,
+            parent,
+            collectsFromSingleBucket,
+            metadata
+        );
+        this.valuesSource = (ValuesSource.Range) valuesSource;
+        if (this.valuesSource.rangeType().isNumeric() == false) {
+            throw new IllegalArgumentException(
+                "Expected numeric range type but found non-numeric range [" + this.valuesSource.rangeType().name + "]"
+            );
         }
-        this.interval = interval;
-        this.offset = offset;
-        this.order = order;
-        order.validate(this);
-        this.keyed = keyed;
-        this.minDocCount = minDocCount;
-        this.minBound = minBound;
-        this.maxBound = maxBound;
-        this.valuesSource = valuesSource;
-        this.formatter = formatter;
-
-        bucketOrds = new LongHash(1, context.bigArrays());
     }
 
     @Override
@@ -88,8 +91,7 @@ public class RangeHistogramAggregator extends BucketsAggregator {
         final RangeType rangeType = valuesSource.rangeType();
         return new LeafBucketCollectorBase(sub, values) {
             @Override
-            public void collect(int doc, long bucket) throws IOException {
+            public void collect(int doc, long owningBucketOrd) throws IOException {
-                assert bucket == 0;
                 if (values.advanceExact(doc)) {
                     // Is it possible for valuesCount to be > 1 here? Multiple ranges are encoded into the same BytesRef in the binary doc
                     // values, so it isn't clear what we'd be iterating over.
@@ -113,7 +115,7 @@ public class RangeHistogramAggregator extends BucketsAggregator {
                                     continue;
                                 }
                                 // Bucket collection identical to NumericHistogramAggregator, could be refactored
-                                long bucketOrd = bucketOrds.add(Double.doubleToLongBits(key));
+                                long bucketOrd = bucketOrds.add(owningBucketOrd, Double.doubleToLongBits(key));
                                 if (bucketOrd < 0) { // already seen
                                     bucketOrd = -1 - bucketOrd;
                                     collectExistingBucket(sub, doc, bucketOrd);
@@ -131,39 +133,4 @@ public class RangeHistogramAggregator extends BucketsAggregator {
             }
         };
     }
-
-    // TODO: buildAggregations and buildEmptyAggregation are literally just copied out of NumericHistogramAggregator.  We could refactor
-    // this to an abstract super class, if we wanted to.  Might be overkill.
-    @Override
-    public InternalAggregation[] buildAggregations(long[] owningBucketOrds) throws IOException {
-        return buildAggregationsForVariableBuckets(owningBucketOrds, bucketOrds,
-            (bucketValue, docCount, subAggregationResults) -> {
-                double roundKey = Double.longBitsToDouble(bucketValue);
-                double key = roundKey * interval + offset;
-                return new InternalHistogram.Bucket(key, docCount, keyed, formatter, subAggregationResults);
-            }, buckets -> {
-                // the contract of the histogram aggregation is that shards must return buckets ordered by key in ascending order
-                CollectionUtil.introSort(buckets, BucketOrder.key(true).comparator());
-
-                EmptyBucketInfo emptyBucketInfo = null;
-                if (minDocCount == 0) {
-                    emptyBucketInfo = new EmptyBucketInfo(interval, offset, minBound, maxBound, buildEmptySubAggregations());
-                }
-                return new InternalHistogram(name, buckets, order, minDocCount, emptyBucketInfo, formatter, keyed, metadata());
-            });
-    }
-
-    @Override
-    public InternalAggregation buildEmptyAggregation() {
-        InternalHistogram.EmptyBucketInfo emptyBucketInfo = null;
-        if (minDocCount == 0) {
-            emptyBucketInfo = new InternalHistogram.EmptyBucketInfo(interval, offset, minBound, maxBound, buildEmptySubAggregations());
-        }
-        return new InternalHistogram(name, Collections.emptyList(), order, minDocCount, emptyBucketInfo, formatter, keyed, metadata());
-    }
-
-    @Override
-    public void doClose() {
-        Releasables.close(bucketOrds);
-    }
 }

server/src/main/java/org/elasticsearch/search/aggregations/support/HistogramAggregatorSupplier.java

@@ -29,9 +29,21 @@ import java.io.IOException;
 import java.util.Map;
 
 public interface HistogramAggregatorSupplier extends AggregatorSupplier {
-    Aggregator build(String name, AggregatorFactories factories, double interval, double offset,
+    Aggregator build(
-                     BucketOrder order, boolean keyed, long minDocCount, double minBound, double maxBound,
+        String name,
-                     @Nullable ValuesSource valuesSource, DocValueFormat formatter,
+        AggregatorFactories factories,
-                     SearchContext context, Aggregator parent,
+        double interval,
-                     Map<String, Object> metadata) throws IOException;
+        double offset,
+        BucketOrder order,
+        boolean keyed,
+        long minDocCount,
+        double minBound,
+        double maxBound,
+        @Nullable ValuesSource valuesSource,
+        DocValueFormat formatter,
+        SearchContext context,
+        Aggregator parent,
+        boolean collectsFromSingleBucket,
+        Map<String, Object> metadata
+    ) throws IOException;
 }

server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/NumericHistogramAggregatorTests.java

@@ -23,23 +23,32 @@ import org.apache.lucene.document.Document;
 import org.apache.lucene.document.SortedNumericDocValuesField;
 import org.apache.lucene.document.SortedSetDocValuesField;
 import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.IndexableField;
 import org.apache.lucene.index.RandomIndexWriter;
 import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.MatchAllDocsQuery;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.NumericUtils;
+import org.elasticsearch.common.CheckedConsumer;
 import org.elasticsearch.index.mapper.DateFieldMapper;
-import org.elasticsearch.index.mapper.KeywordFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.NumberFieldMapper;
+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.support.AggregationInspectionHelper;
 
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Consumer;
 
 import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasSize;
 
 public class NumericHistogramAggregatorTests extends AggregatorTestCase {
 
@@ -55,11 +64,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                     .field("field")
                     .interval(5);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, longField("field"));
                 assertEquals(4, histogram.getBuckets().size());
                 assertEquals(-10d, histogram.getBuckets().get(0).getKey());
                 assertEquals(2, histogram.getBuckets().get(0).getDocCount());
@@ -86,11 +93,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                     .field("field")
                     .interval(5);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.DOUBLE);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, doubleField("field"));
                 assertEquals(4, histogram.getBuckets().size());
                 assertEquals(-10d, histogram.getBuckets().get(0).getKey());
                 assertEquals(2, histogram.getBuckets().get(0).getDocCount());
@@ -119,10 +124,7 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             "2019-11-10T22:55:46");
 
         String fieldName = "date_field";
-        DateFieldMapper.Builder builder = new DateFieldMapper.Builder(fieldName);
+        DateFieldMapper.DateFieldType fieldType = dateField(fieldName, DateFieldMapper.Resolution.MILLISECONDS);
-        DateFieldMapper.DateFieldType fieldType = builder.fieldType();
-        fieldType.setName(fieldName);
-        fieldType.setHasDocValues(true);
 
         try (Directory dir = newDirectory();
              RandomIndexWriter indexWriter = new RandomIndexWriter(random(), dir)) {
@@ -161,11 +163,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                     .field("field")
                     .interval(Math.PI);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, longField("field"));
                 assertEquals(4, histogram.getBuckets().size());
                 assertEquals(-4 * Math.PI, histogram.getBuckets().get(0).getKey());
                 assertEquals(1, histogram.getBuckets().get(0).getDocCount());
@@ -193,11 +193,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
                     .field("field")
                     .interval(10)
                     .minDocCount(2);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = searchAndReduce(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = searchAndReduce(searcher, new MatchAllDocsQuery(), aggBuilder, longField("field"));
                 assertEquals(2, histogram.getBuckets().size());
                 assertEquals(-10d, histogram.getBuckets().get(0).getKey());
                 assertEquals(2, histogram.getBuckets().get(0).getDocCount());
@@ -222,11 +220,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
                     .field("field")
                     .interval(5)
                     .missing(2d);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, longField("field"));
                 assertEquals(4, histogram.getBuckets().size());
                 assertEquals(-10d, histogram.getBuckets().get(0).getKey());
                 assertEquals(2, histogram.getBuckets().get(0).getDocCount());
@@ -304,8 +300,7 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(5);
-            MappedFieldType fieldType = new KeywordFieldMapper.KeywordFieldType();
+            MappedFieldType fieldType = keywordField("field");
-            fieldType.setName("field");
             fieldType.setHasDocValues(true);
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
@@ -331,11 +326,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
                     .field("field")
                     .interval(5)
                     .offset(Math.PI);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.DOUBLE);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, doubleField("field"));
                 assertEquals(3, histogram.getBuckets().size());
                 assertEquals(-10 + Math.PI, histogram.getBuckets().get(0).getKey());
                 assertEquals(2, histogram.getBuckets().get(0).getDocCount());
@@ -365,11 +358,9 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
                 .field("field")
                 .interval(interval)
                 .offset(offset);
-            MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.DOUBLE);
-            fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, doubleField("field"));
                 assertEquals(3, histogram.getBuckets().size());
 
                 assertEquals(-10 + expectedOffset, histogram.getBuckets().get(0).getKey());
@@ -403,7 +394,7 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             fieldType.setName("field");
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = searchAndReduce(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = searchAndReduce(searcher, new MatchAllDocsQuery(), aggBuilder, doubleField("field"));
                 assertEquals(6, histogram.getBuckets().size());
                 assertEquals(-15d, histogram.getBuckets().get(0).getKey());
                 assertEquals(0, histogram.getBuckets().get(0).getDocCount());
@@ -421,4 +412,37 @@ public class NumericHistogramAggregatorTests extends AggregatorTestCase {
             }
         }
     }
+
+    public void testAsSubAgg() throws IOException {
+        AggregationBuilder request = new HistogramAggregationBuilder("outer").field("outer").interval(5).subAggregation(
+            new HistogramAggregationBuilder("inner").field("inner").interval(5).subAggregation(
+                new MinAggregationBuilder("min").field("n")));
+        CheckedConsumer<RandomIndexWriter, IOException> buildIndex = iw -> {
+            List<List<IndexableField>> docs = new ArrayList<>();
+            for (int n = 0; n < 10000; n++) {
+                docs.add(org.elasticsearch.common.collect.List.of(
+                    new SortedNumericDocValuesField("outer", n % 100),
+                    new SortedNumericDocValuesField("inner", n / 100),
+                    new SortedNumericDocValuesField("n", n)
+                ));
+            }
+            iw.addDocuments(docs);
+        };
+        Consumer<InternalHistogram> verify = outer -> {
+            assertThat(outer.getBuckets(), hasSize(20));
+            for (int outerIdx = 0; outerIdx < 20; outerIdx++) {
+                InternalHistogram.Bucket outerBucket = outer.getBuckets().get(outerIdx);
+                assertThat(outerBucket.getKey(), equalTo(5.0 * outerIdx));
+                InternalHistogram inner = outerBucket.getAggregations().get("inner");
+                assertThat(inner.getBuckets(), hasSize(20));
+                for (int innerIdx = 0; innerIdx < 20; innerIdx++) {
+                    InternalHistogram.Bucket innerBucket = inner.getBuckets().get(innerIdx);
+                    assertThat(innerBucket.getKey(), equalTo(5.0 * innerIdx));
+                    InternalMin min = innerBucket.getAggregations().get("min");
+                    assertThat(min.getValue(), equalTo(outerIdx * 5.0 + innerIdx * 500.0));
+                }
+            }
+        };
+        testCase(request, new MatchAllDocsQuery(), buildIndex, verify, longField("outer"), longField("inner"), longField("n"));
+    }
 }

server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/RangeHistogramAggregatorTests.java

@@ -21,29 +21,35 @@ package org.elasticsearch.search.aggregations.bucket.histogram;
 
 import org.apache.lucene.document.BinaryDocValuesField;
 import org.apache.lucene.document.Document;
+import org.apache.lucene.document.SortedNumericDocValuesField;
 import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.IndexableField;
 import org.apache.lucene.index.RandomIndexWriter;
 import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.MatchAllDocsQuery;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.common.CheckedConsumer;
 import org.elasticsearch.common.network.InetAddresses;
-import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.RangeFieldMapper;
 import org.elasticsearch.index.mapper.RangeType;
+import org.elasticsearch.search.aggregations.AggregationBuilder;
 import org.elasticsearch.search.aggregations.AggregatorTestCase;
-import org.junit.Rule;
+import org.elasticsearch.search.aggregations.metrics.InternalMin;
-import org.junit.rules.ExpectedException;
+import org.elasticsearch.search.aggregations.metrics.MinAggregationBuilder;
 
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Set;
 import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Consumer;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasSize;
 
 public class RangeHistogramAggregatorTests extends AggregatorTestCase {
-
-    @Rule
-    public final ExpectedException expectedException = ExpectedException.none();
-
     public void testDoubles() throws Exception {
         RangeType rangeType = RangeType.DOUBLE;
         try (Directory dir = newDirectory();
@@ -63,12 +69,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(5);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 assertEquals(6, histogram.getBuckets().size());
 
                 assertEquals(-5d, histogram.getBuckets().get(0).getKey());
@@ -111,12 +114,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(5);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 assertEquals(6, histogram.getBuckets().size());
 
                 assertEquals(-5d, histogram.getBuckets().get(0).getKey());
@@ -157,12 +157,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(5);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 assertEquals(6, histogram.getBuckets().size());
 
                 assertEquals(-5d, histogram.getBuckets().get(0).getKey());
@@ -204,12 +201,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(5);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 assertEquals(3, histogram.getBuckets().size());
 
                 assertEquals(0d, histogram.getBuckets().get(0).getKey());
@@ -243,12 +237,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(Math.PI);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 assertEquals(6, histogram.getBuckets().size());
 
                 assertEquals(-1 * Math.PI, histogram.getBuckets().get(0).getKey());
@@ -292,12 +283,14 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
                 .field("field")
                 .interval(5)
                 .minDocCount(2);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = searchAndReduce(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = searchAndReduce(
+                    searcher,
+                    new MatchAllDocsQuery(),
+                    aggBuilder,
+                    rangeField("field", rangeType)
+                );
                 assertEquals(2, histogram.getBuckets().size());
 
                 assertEquals(5d, histogram.getBuckets().get(0).getKey());
@@ -329,12 +322,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
                 .field("field")
                 .interval(5)
                 .offset(4);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 //assertEquals(7, histogram.getBuckets().size());
 
                 assertEquals(-6d, histogram.getBuckets().get(0).getKey());
@@ -387,12 +377,9 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
                 .field("field")
                 .interval(interval)
                 .offset(offset);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
-
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                InternalHistogram histogram = search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType));
                 assertEquals(6, histogram.getBuckets().size());
 
                 assertEquals(-5d + expectedOffset, histogram.getBuckets().get(0).getKey());
@@ -431,16 +418,64 @@ public class RangeHistogramAggregatorTests extends AggregatorTestCase {
             HistogramAggregationBuilder aggBuilder = new HistogramAggregationBuilder("my_agg")
                 .field("field")
                 .interval(5);
-            MappedFieldType fieldType = new RangeFieldMapper.Builder("field", rangeType).fieldType();
-            fieldType.setName("field");
 
             try (IndexReader reader = w.getReader()) {
                 IndexSearcher searcher = new IndexSearcher(reader);
-                expectedException.expect(IllegalArgumentException.class);
+                Exception e = expectThrows(IllegalArgumentException.class, () ->
-                search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                    search(searcher, new MatchAllDocsQuery(), aggBuilder, rangeField("field", rangeType)));
+                assertThat(e.getMessage(), equalTo("Expected numeric range type but found non-numeric range [ip_range]"));
             }
         }
-
     }
 
+    public void testAsSubAgg() throws IOException {
+        AggregationBuilder request = new HistogramAggregationBuilder("outer").field("outer").interval(5).subAggregation(
+            new HistogramAggregationBuilder("inner").field("inner").interval(5).subAggregation(
+                new MinAggregationBuilder("min").field("n")));
+        CheckedConsumer<RandomIndexWriter, IOException> buildIndex = iw -> {
+            List<List<IndexableField>> docs = new ArrayList<>();
+            for (int n = 0; n < 10000; n++) {
+                BytesRef outerRange = RangeType.LONG.encodeRanges(org.elasticsearch.common.collect.Set.of(
+                    new RangeFieldMapper.Range(RangeType.LONG, n % 100, n % 100 + 10, true, true)
+                ));
+                BytesRef innerRange = RangeType.LONG.encodeRanges(org.elasticsearch.common.collect.Set.of(
+                    new RangeFieldMapper.Range(RangeType.LONG, n / 100, n / 100 + 10, true, true)
+                ));
+
+                docs.add(org.elasticsearch.common.collect.List.of(
+                    new BinaryDocValuesField("outer", outerRange),
+                    new BinaryDocValuesField("inner", innerRange),
+                    new SortedNumericDocValuesField("n", n)
+                ));
+            }
+            iw.addDocuments(docs);
+        };
+        Consumer<InternalHistogram> verify = outer -> {
+            assertThat(outer.getBuckets(), hasSize(22));
+            for (int outerIdx = 0; outerIdx < 22; outerIdx++) {
+                InternalHistogram.Bucket outerBucket = outer.getBuckets().get(outerIdx);
+                assertThat(outerBucket.getKey(), equalTo(5.0 * outerIdx));
+                InternalHistogram inner = outerBucket.getAggregations().get("inner");
+                assertThat(inner.getBuckets(), hasSize(22));
+                for (int innerIdx = 0; innerIdx < 22; innerIdx++) {
+                    InternalHistogram.Bucket innerBucket = inner.getBuckets().get(innerIdx);
+                    assertThat(innerBucket.getKey(), equalTo(5.0 * innerIdx));
+                    InternalMin min = innerBucket.getAggregations().get("min");
+                    int minOuterIdxWithOverlappingRange = Math.max(0, outerIdx - 2);
+                    int minInnerIdxWithOverlappingRange = Math.max(0, innerIdx - 2);
+                    assertThat(min.getValue(),
+                            equalTo(minOuterIdxWithOverlappingRange * 5.0 + minInnerIdxWithOverlappingRange * 500.0));
+                }
+            }
+        };
+        testCase(
+            request,
+            new MatchAllDocsQuery(),
+            buildIndex,
+            verify,
+            rangeField("outer", RangeType.LONG),
+            rangeField("inner", RangeType.LONG),
+            longField("n")
+        );
+    }
 }

server/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/SignificantTermsAggregatorTests.java

@@ -416,12 +416,6 @@ public class SignificantTermsAggregatorTests extends AggregatorTestCase {
         }
     }
 
-    private NumberFieldMapper.NumberFieldType longField(String name) {
-        NumberFieldMapper.NumberFieldType type = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
-        type.setName(name);
-        return type;
-    }
-
     private void addMixedTextDocs(TextFieldType textFieldType, IndexWriter w) throws IOException {
         for (int i = 0; i < 10; i++) {
             Document doc = new Document();

server/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorTests.java

@@ -1347,12 +1347,6 @@ public class TermsAggregatorTests extends AggregatorTestCase {
         }
     }
 
-    private NumberFieldMapper.NumberFieldType longField(String name) {
-        NumberFieldMapper.NumberFieldType type = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
-        type.setName(name);
-        return type;
-    }
-
     private void assertNestedTopHitsScore(InternalMultiBucketAggregation<?, ?> terms, boolean withScore) {
         assertThat(terms.getBuckets().size(), equalTo(9));
         int ptr = 9;

test/framework/src/main/java/org/elasticsearch/search/aggregations/AggregatorTestCase.java

@@ -73,9 +73,11 @@ import org.elasticsearch.index.fielddata.IndexFieldDataService;
 import org.elasticsearch.index.mapper.BinaryFieldMapper;
 import org.elasticsearch.index.mapper.CompletionFieldMapper;
 import org.elasticsearch.index.mapper.ContentPath;
+import org.elasticsearch.index.mapper.DateFieldMapper;
 import org.elasticsearch.index.mapper.FieldAliasMapper;
 import org.elasticsearch.index.mapper.FieldMapper;
 import org.elasticsearch.index.mapper.GeoShapeFieldMapper;
+import org.elasticsearch.index.mapper.KeywordFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.Mapper;
 import org.elasticsearch.index.mapper.Mapper.BuilderContext;
@@ -865,4 +867,50 @@ public abstract class AggregatorTestCase extends ESTestCase {
         Releasables.close(releasables);
         releasables.clear();
     }
+
+    /**
+     * Make a {@linkplain DateFieldMapper.DateFieldType} for a {@code date}.
+     */
+    protected DateFieldMapper.DateFieldType dateField(String name, DateFieldMapper.Resolution resolution) {
+        DateFieldMapper.Builder builder = new DateFieldMapper.Builder(name);
+        builder.withResolution(resolution);
+        Settings settings = Settings.builder().put("index.version.created", Version.CURRENT.id).build();
+        return builder.build(new BuilderContext(settings, new ContentPath())).fieldType();
+    }
+
+    /**
+     * Make a {@linkplain NumberFieldMapper.NumberFieldType} for a {@code double}.
+     */
+    protected NumberFieldMapper.NumberFieldType doubleField(String name) {
+        NumberFieldMapper.NumberFieldType result = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.DOUBLE);
+        result.setName(name);
+        return result;
+    }
+
+    /**
+     * Make a {@linkplain DateFieldMapper.DateFieldType} for a {@code date}.
+     */
+    protected KeywordFieldMapper.KeywordFieldType keywordField(String name) {
+        KeywordFieldMapper.KeywordFieldType result = new KeywordFieldMapper.KeywordFieldType();
+        result.setName(name);
+        return result;
+    }
+
+    /**
+     * Make a {@linkplain NumberFieldMapper.NumberFieldType} for a {@code long}.
+     */
+    protected NumberFieldMapper.NumberFieldType longField(String name) {
+        NumberFieldMapper.NumberFieldType result = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
+        result.setName(name);
+        return result;
+    }
+
+    /**
+     * Make a {@linkplain NumberFieldMapper.NumberFieldType} for a {@code range}.
+     */
+    protected RangeFieldMapper.RangeFieldType rangeField(String name, RangeType rangeType) {
+        RangeFieldMapper.RangeFieldType result = new RangeFieldMapper.Builder(name, rangeType).fieldType();
+        result.setName(name);
+        return result;
+    }
 }