Fix date_nanos in composite aggs (#53315)

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/230_composite.yml

@@ -886,6 +886,66 @@ setup:
   - match: { aggregations.test.buckets.0.key.date: "2017-10-21T00:00:00.000-02:00" }
   - match: { aggregations.test.buckets.0.doc_count: 2 }
 
+---
+"date_histogram on date_nanos":
+  - skip:
+      version: " - 7.6.99"
+      reason: Fixed in 7.7.0
+  - do:
+        indices.create:
+          index: test_nanos
+          body:
+              mappings:
+                properties:
+                  date_nanos:
+                    type: date_nanos
+
+  - do:
+      index:
+        index:   test_nanos
+        id:      7
+        body:    { "date_nanos": "2017-11-21T01:00:00" }
+        refresh: true
+  - do:
+      index:
+        index:   test_nanos
+        id:      8
+        body:    { "date_nanos": "2017-11-22T01:00:00" }
+        refresh: true
+  - do:
+      index:
+        index:   test_nanos
+        id:      9
+        body:    { "date_nanos": "2017-11-22T02:00:00" }
+        refresh: true
+  - do:
+      search:
+        index: test_nanos
+        body:
+          aggregations:
+            test:
+              composite:
+                sources:
+                  - date:
+                      date_histogram:
+                        field: date_nanos
+                        calendar_interval: 1d
+                        format: iso8601 # Format makes the comparisons a little more obvious
+              aggregations:
+                avg:
+                  avg:
+                    field: date_nanos
+
+  - match: { hits.total.value: 3 }
+  - match: { hits.total.relation: eq }
+  - length: { aggregations.test.buckets: 2 }
+  - match: { aggregations.test.buckets.0.key.date: "2017-11-21T00:00:00.000Z" }
+  - match: { aggregations.test.buckets.0.doc_count: 1 }
+  - match: { aggregations.test.buckets.0.avg.value_as_string: "2017-11-21T01:00:00.000Z" }
+  - match: { aggregations.test.buckets.1.key.date: "2017-11-22T00:00:00.000Z" }
+  - match: { aggregations.test.buckets.1.doc_count: 2 }
+  - match: { aggregations.test.buckets.1.avg.value_as_string: "2017-11-22T01:30:00.000Z" }
+
 ---
 "Terms source from sorted":
   - do:

server/src/main/java/org/elasticsearch/index/mapper/DateFieldMapper.java

@@ -94,6 +94,11 @@ public Instant toInstant(long value) {
             public Instant clampToValidRange(Instant instant) {
                 return instant;
             }
+
+            @Override
+            public long parsePointAsMillis(byte[] value) {
+                return LongPoint.decodeDimension(value, 0);
+            }
         },
         NANOSECONDS("date_nanos", NumericType.DATE_NANOSECONDS) {
             @Override
@@ -110,6 +115,11 @@ public Instant toInstant(long value) {
             public Instant clampToValidRange(Instant instant) {
                 return DateUtils.clampToNanosRange(instant);
             }
+
+            @Override
+            public long parsePointAsMillis(byte[] value) {
+                return DateUtils.toMilliSeconds(LongPoint.decodeDimension(value, 0));
+            }
         };
 
         private final String type;
@@ -138,8 +148,17 @@ NumericType numericType() {
          */
         public abstract Instant toInstant(long value);
 
+        /**
+         * Return the instant that this range can represent that is closest to
+         * the provided instant.
+         */
         public abstract Instant clampToValidRange(Instant instant);
 
+        /**
+         * Decode the points representation of this field as milliseconds.
+         */
+        public abstract long parsePointAsMillis(byte[] value);
+
         public static Resolution ofOrdinal(int ord) {
             for (Resolution resolution : values()) {
                 if (ord == resolution.ordinal()) {

server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/LongValuesSource.java

@@ -269,7 +269,8 @@ SortedDocsProducer createSortedDocsProducerOrNull(IndexReader reader, Query quer
             }
             return new PointsSortedDocsProducer(fieldType.name(), toBucketFunction, lowerPoint, upperPoint);
         } else if (fieldType instanceof DateFieldMapper.DateFieldType) {
-            final ToLongFunction<byte[]> toBucketFunction = (value) -> rounding.applyAsLong(LongPoint.decodeDimension(value, 0));
+            ToLongFunction<byte[]> decode = ((DateFieldMapper.DateFieldType) fieldType).resolution()::parsePointAsMillis;
+            ToLongFunction<byte[]> toBucketFunction = value -> rounding.applyAsLong(decode.applyAsLong(value));
             return new PointsSortedDocsProducer(fieldType.name(), toBucketFunction, lowerPoint, upperPoint);
         } else {
             return null;

server/src/main/java/org/elasticsearch/search/aggregations/metrics/MinAggregator.java

@@ -18,15 +18,14 @@
  */
 package org.elasticsearch.search.aggregations.metrics;
 
-import org.apache.lucene.document.LongPoint;
 import org.apache.lucene.index.IndexOptions;
 import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.index.PointValues;
 import org.apache.lucene.search.CollectionTerminatedException;
 import org.apache.lucene.search.MatchAllDocsQuery;
-import org.apache.lucene.util.Bits;
 import org.apache.lucene.search.ScoreMode;
+import org.apache.lucene.util.Bits;
 import org.elasticsearch.common.lease.Releasables;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.DoubleArray;
@@ -191,11 +190,7 @@ static Function<byte[], Number> getPointReaderOrNull(SearchContext context, Aggr
                 converter = ((NumberFieldMapper.NumberFieldType) fieldType)::parsePoint;
             } else if (fieldType.getClass() == DateFieldMapper.DateFieldType.class) {
                 DateFieldMapper.DateFieldType dft = (DateFieldMapper.DateFieldType) fieldType;
-                /*
-                 * Makes sure that nanoseconds decode to milliseconds, just
-                 * like they do when you run the agg without the optimization.
-                 */
-                converter = (in) -> dft.resolution().toInstant(LongPoint.decodeDimension(in, 0)).toEpochMilli();
+                converter = dft.resolution()::parsePointAsMillis;
             }
             return converter;
         }