Handle _shard_doc field for sort optimization (#69321)

This commit ensures that the automatic tiebreaker `_shard_doc` does not disable sort optimization. Relates #56828
elastic · Feb 22, 2021 · bd4a585 · bd4a585
1 parent 93b888e
commit bd4a585
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/server/src/main/java/org/elasticsearch/search/query/QueryPhase.java b/server/src/main/java/org/elasticsearch/search/query/QueryPhase.java
@@ -56,6 +56,7 @@
 import org.elasticsearch.search.profile.SearchProfileShardResults;
 import org.elasticsearch.search.profile.query.InternalProfileCollector;
 import org.elasticsearch.search.rescore.RescorePhase;
+import org.elasticsearch.search.sort.FieldSortBuilder;
 import org.elasticsearch.search.sort.SortAndFormats;
 import org.elasticsearch.search.suggest.SuggestPhase;
 import org.elasticsearch.tasks.TaskCancelledException;
@@ -428,10 +429,14 @@ private static Query tryRewriteLongSort(SearchContext searchContext, IndexReader
             SortField sField = sort.getSort()[i];
             String sFieldName = sField.getField();
             if (sFieldName == null) {
-                if (SortField.FIELD_DOC.equals(sField) == false) return null;
-            } else {
+                if (SortField.FIELD_DOC.equals(sField) == false) {
+                    return null;
+                }
+            } else if (FieldSortBuilder.SHARD_DOC_FIELD_NAME.equals(sFieldName) == false) {
                 //TODO: find out how to cover _script sort that don't use _score
-                if (searchExecutionContext.getFieldType(sFieldName) == null) return null; // could be _script sort that uses _score
+                if (searchExecutionContext.getFieldType(sFieldName) == null) {
+                    return null; // could be _script sort that uses _score
+                }
             }
         }