Expand streaming aggregations to numeric terms (opensearch-project#19335)

* Expand streaming aggregations to numeric terms

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* Add tests

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* Changelog

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* Fix gradle assemble

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* update test coverage

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* remove custom stream package

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* remove custom stream package

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* remove unused results

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

---------

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

Author: harshavamsi

CHANGELOG.md

@@ -50,6 +50,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add sub aggregation support for histogram aggregation using skiplist ([19438](https://github.com/opensearch-project/OpenSearch/pull/19438))
 - Optimization in String Terms Aggregation query for Large Bucket Counts([#18732](https://github.com/opensearch-project/OpenSearch/pull/18732))
 - New cluster setting search.query.max_query_string_length ([#19491](https://github.com/opensearch-project/OpenSearch/pull/19491))
+- Add `StreamNumericTermsAggregator` to allow numeric term aggregation streaming ([#19335](https://github.com/opensearch-project/OpenSearch/pull/19335))
 
 ### Changed
 - Refactor `if-else` chains to use `Java 17 pattern matching switch expressions`(([#18965](https://github.com/opensearch-project/OpenSearch/pull/18965))

server/src/main/java/org/opensearch/search/aggregations/bucket/BucketsAggregator.java

@@ -53,7 +53,6 @@
 import java.io.IOException;
 import java.util.AbstractList;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -260,23 +259,6 @@ public int size() {
         return result;
     }
 
-    /**
-     * Build the sub aggregation results for a list of buckets and set them on
-     * the buckets. This is usually used by aggregations that are selective
-     * in which bucket they build. They use some mechanism of selecting a list
-     * of buckets to build use this method to "finish" building the results.
-     * @param buckets the buckets to finish building
-     * @param bucketToOrd how to convert a bucket into an ordinal
-     * @param setAggs how to set the sub-aggregation results on a bucket
-     */
-    protected final <B> void buildSubAggsForBuckets(B[] buckets, ToLongFunction<B> bucketToOrd, BiConsumer<B, InternalAggregations> setAggs)
-        throws IOException {
-        InternalAggregations[] results = buildSubAggsForBuckets(Arrays.stream(buckets).mapToLong(bucketToOrd).toArray());
-        for (int i = 0; i < buckets.length; i++) {
-            setAggs.accept(buckets[i], results[i]);
-        }
-    }
-
     /**
      * Build the sub aggregation results for a list of buckets and set them on
      * the buckets. This is usually used by aggregations that are selective

server/src/main/java/org/opensearch/search/aggregations/bucket/terms/InternalSignificantTerms.java

@@ -88,7 +88,7 @@ public interface Reader<B extends Bucket<B>> {
         long supersetSize;
         long bucketOrd;
         double score;
-        protected InternalAggregations aggregations;
+        InternalAggregations aggregations;
         final transient DocValueFormat format;
 
         protected Bucket(

server/src/main/java/org/opensearch/search/aggregations/bucket/terms/InternalTerms.java

@@ -106,9 +106,9 @@ public interface Reader<B extends Bucket<B>> {
 
         long bucketOrd;
 
-        protected long docCount;
+        long docCount;
         protected long docCountError;
-        protected InternalAggregations aggregations;
+        InternalAggregations aggregations;
         protected final boolean showDocCountError;
         protected final DocValueFormat format;