1 files changed, 10 insertions, 0 deletions
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index 8446ca46e3c..a7a0a96ce10 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -7136,6 +7136,16 @@ view_err:
           /* Non-primary unique key. */
           needed_online_flags|=  HA_ONLINE_ADD_UNIQUE_INDEX;
           needed_fast_flags|= HA_ONLINE_ADD_UNIQUE_INDEX_NO_WRITES;
+          if (ignore)
+          {
+            /*
+              If ignore is used, we have to remove all duplicate rows,
+              which require a full table copy.
+            */
+            need_copy_table= ALTER_TABLE_DATA_CHANGED;
+            pk_changed= 2;                      // Don't change need_copy_table
+            break;
+          }
         }
       }
       else