1 files changed, 13 insertions, 1 deletions
diff --git a/document/src/main/java/com/yahoo/document/serialization/VespaDocumentSerializerHead.java b/document/src/main/java/com/yahoo/document/serialization/VespaDocumentSerializerHead.java
index 66bc8cbb4d5..b2c3cdc09de 100644
--- a/document/src/main/java/com/yahoo/document/serialization/VespaDocumentSerializerHead.java
+++ b/document/src/main/java/com/yahoo/document/serialization/VespaDocumentSerializerHead.java
@@ -19,10 +19,22 @@ public class VespaDocumentSerializerHead extends VespaDocumentSerializer6 {
 
     @Override
     public void write(TensorModifyUpdate update) {
-        putByte(null, (byte) update.getOperation().id);
+        putByte(null, (byte) encodeOperationId(update));
+        if (update.getCreateNonExistingCells()) {
+            putDouble(null, update.getDefaultCellValue());
+        }
         update.getValue().serialize(this);
     }
 
+    private int encodeOperationId(TensorModifyUpdate update) {
+        int operationId = update.getOperation().id;
+        byte CREATE_FLAG = -0b10000000;
+        if (update.getCreateNonExistingCells()) {
+            operationId |= CREATE_FLAG;
+        }
+        return operationId;
+    }
+
     @Override
     public void write(TensorAddUpdate update) {
         update.getValue().serialize(this);