Removes parent child fielddata specialization (#24737)

This change removes the field data specialization needed for the parent field and replaces it with
a simple DocValuesIndexFieldData. The underlying global ordinals are retrieved via a new function called
IndexOrdinalsFieldData#getOrdinalMap.
The children aggregation is also modified to use a simple WithOrdinals value source rather than the deleted WithOrdinals.Parent.

Relates #20257

2 files changed, 1 insertions, 42 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSource.java b/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSource.java
index e6ed81c2d8..a8aaa25940 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSource.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSource.java
@@ -22,7 +22,6 @@ import org.apache.lucene.index.DirectoryReader;
 import org.apache.lucene.index.DocValues;
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.LeafReaderContext;
-import org.apache.lucene.index.SortedDocValues;
 import org.apache.lucene.index.SortedNumericDocValues;
 import org.apache.lucene.index.SortedSetDocValues;
 import org.apache.lucene.search.IndexSearcher;
@@ -32,18 +31,15 @@ import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.lucene.ScorerAware;
 import org.elasticsearch.index.fielddata.AbstractSortingNumericDocValues;
 import org.elasticsearch.index.fielddata.AtomicOrdinalsFieldData;
-import org.elasticsearch.index.fielddata.AtomicParentChildFieldData;
 import org.elasticsearch.index.fielddata.IndexFieldData;
 import org.elasticsearch.index.fielddata.IndexGeoPointFieldData;
 import org.elasticsearch.index.fielddata.IndexNumericFieldData;
 import org.elasticsearch.index.fielddata.IndexOrdinalsFieldData;
-import org.elasticsearch.index.fielddata.IndexParentChildFieldData;
 import org.elasticsearch.index.fielddata.MultiGeoPointValues;
 import org.elasticsearch.index.fielddata.SortedBinaryDocValues;
 import org.elasticsearch.index.fielddata.SortedNumericDoubleValues;
 import org.elasticsearch.index.fielddata.SortingBinaryDocValues;
 import org.elasticsearch.index.fielddata.SortingNumericDoubleValues;
-import org.elasticsearch.index.fielddata.plain.ParentChildIndexFieldData;
 import org.elasticsearch.script.LeafSearchScript;
 import org.elasticsearch.script.SearchScript;
 import org.elasticsearch.search.aggregations.support.ValuesSource.WithScript.BytesValues;
@@ -150,40 +146,6 @@ public abstract class ValuesSource {
             }
         }
 
-        public static class ParentChild extends Bytes {
-
-            protected final ParentChildIndexFieldData indexFieldData;
-
-            public ParentChild(ParentChildIndexFieldData indexFieldData) {
-                this.indexFieldData = indexFieldData;
-            }
-
-            public long globalMaxOrd(IndexSearcher indexSearcher, String type) {
-                DirectoryReader indexReader = (DirectoryReader) indexSearcher.getIndexReader();
-                if (indexReader.leaves().isEmpty()) {
-                    return 0;
-                } else {
-                    LeafReaderContext atomicReaderContext = indexReader.leaves().get(0);
-                    IndexParentChildFieldData globalFieldData = indexFieldData.loadGlobal(indexReader);
-                    AtomicParentChildFieldData afd = globalFieldData.load(atomicReaderContext);
-                    SortedDocValues values = afd.getOrdinalsValues(type);
-                    return values.getValueCount();
-                }
-            }
-
-            public SortedDocValues globalOrdinalsValues(String type, LeafReaderContext context) {
-                final IndexParentChildFieldData global = indexFieldData.loadGlobal((DirectoryReader)context.parent.reader());
-                final AtomicParentChildFieldData atomicFieldData = global.load(context);
-                return atomicFieldData.getOrdinalsValues(type);
-            }
-
-            @Override
-            public SortedBinaryDocValues bytesValues(LeafReaderContext context) {
-                final AtomicParentChildFieldData atomicFieldData = indexFieldData.load(context);
-                return atomicFieldData.getBytesValues();
-            }
-        }
-
         public static class FieldData extends Bytes {
 
             protected final IndexFieldData<?> indexFieldData;
diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSourceConfig.java b/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSourceConfig.java
index 39b97a9b02..e5fac62840 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSourceConfig.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSourceConfig.java
@@ -26,7 +26,6 @@ import org.elasticsearch.index.fielddata.IndexFieldData;
 import org.elasticsearch.index.fielddata.IndexGeoPointFieldData;
 import org.elasticsearch.index.fielddata.IndexNumericFieldData;
 import org.elasticsearch.index.fielddata.IndexOrdinalsFieldData;
-import org.elasticsearch.index.fielddata.plain.ParentChildIndexFieldData;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.script.Script;
@@ -317,9 +316,7 @@ public class ValuesSourceConfig<VS extends ValuesSource> {
     private ValuesSource bytesField() throws IOException {
         final IndexFieldData<?> indexFieldData = fieldContext().indexFieldData();
         ValuesSource dataSource;
-        if (indexFieldData instanceof ParentChildIndexFieldData) {
-            dataSource = new ValuesSource.Bytes.WithOrdinals.ParentChild((ParentChildIndexFieldData) indexFieldData);
-        } else if (indexFieldData instanceof IndexOrdinalsFieldData) {
+        if (indexFieldData instanceof IndexOrdinalsFieldData) {
             dataSource = new ValuesSource.Bytes.WithOrdinals.FieldData((IndexOrdinalsFieldData) indexFieldData);
         } else {
             dataSource = new ValuesSource.Bytes.FieldData(indexFieldData);