1 files changed, 16 insertions, 3 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java b/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java
index 62bc0085422..d96b840dde9 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/StandardDeviationAggregator.java
@@ -6,13 +6,26 @@ package com.yahoo.search.grouping.request;
  * of the values that the contained expression evaluated to over all the inputs.
  *
  * @author bjorncs
+ * @author bratseth
  */
 public class StandardDeviationAggregator extends AggregatorNode {
 
     /**
-     * @param exp The expression to aggregate on.
+     * Constructs a new instance of this class.
+     *
+     * @param expression the expression to aggregate on.
      */
-    public StandardDeviationAggregator(GroupingExpression exp) {
-        super("stddev", exp);
+    public StandardDeviationAggregator(GroupingExpression expression) {
+        this(null, null, expression);
     }
+
+    private StandardDeviationAggregator(String label, Integer level, GroupingExpression expression) {
+        super("stddev", label, level, expression);
+    }
+
+    @Override
+    public StandardDeviationAggregator copy() {
+        return new StandardDeviationAggregator(getLabel(), getLevelOrNull(), getExpression().copy());
+    }
+
 }