diff --git a/Database/APR/RootCollection/src/RootCollectionSchemaEditor.cpp b/Database/APR/RootCollection/src/RootCollectionSchemaEditor.cpp
index af9c06557ff45103edb88d136a16e1d95952b8a6..2b41f3e291dde3cf4ebed9b100e84c8e61d8c4bd 100644
--- a/Database/APR/RootCollection/src/RootCollectionSchemaEditor.cpp
+++ b/Database/APR/RootCollection/src/RootCollectionSchemaEditor.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "CollectionBase/CollectionBaseNames.h"
@@ -222,7 +222,7 @@ dropIndex( const std::vector<std::string>& /* columnNames  */)
 
 void
 pool::RootCollection::RootCollectionSchemaEditor::
-setUniqueConstraint( std::string /* constraintName */, const std::string& /* columnName  */)
+setUniqueConstraint( const std::string& /* constraintName */, const std::string& /* columnName  */)
 {
    methodNotImplemented("setUniqueConstraint ");
 }
@@ -233,7 +233,7 @@ setUniqueConstraint( std::string /* constraintName */, const std::string& /* col
 
 void
 pool::RootCollection::RootCollectionSchemaEditor::
-setUniqueConstraint( std::string /* constraintName */, const std::vector<std::string>& /* columnNames  */)
+setUniqueConstraint( const std::string& /* constraintName */, const std::vector<std::string>& /* columnNames  */)
 {
    methodNotImplemented("setUniqueConstraint ");
 }
diff --git a/Database/APR/RootCollection/src/RootCollectionSchemaEditor.h b/Database/APR/RootCollection/src/RootCollectionSchemaEditor.h
index 61b58281291b57e63a5d5cfa5394777095bd02de..edf8eb8eabc7eccb28647c024a404f1ebd5c01a0 100644
--- a/Database/APR/RootCollection/src/RootCollectionSchemaEditor.h
+++ b/Database/APR/RootCollection/src/RootCollectionSchemaEditor.h
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef ROOTCOLLECTION_COLLECTIONSCHEMAEDITOR_H
@@ -196,7 +196,7 @@ namespace pool {
          *
          * @param columnName Name of column for which constraint is applied.
          */
-        virtual void setUniqueConstraint( std::string constraintName, const std::string& columnName );
+        virtual void setUniqueConstraint( const std::string& constraintName, const std::string& columnName );
 
         /**
          * Sets a unique constraint on one or more columns of the collection. Automatically generates a
@@ -204,7 +204,7 @@ namespace pool {
          *
          * @param columnNames Names of columns for which constraint is applied.
          */
-        virtual void setUniqueConstraint( std::string constraintName, const std::vector<std::string>& columnNames );
+        virtual void setUniqueConstraint( const std::string& constraintName, const std::vector<std::string>& columnNames );
 
         /**
          * Unsets an existing unique constraint on a single column of the collection,