diff --git a/sql/item.h b/sql/item.h
index ae5acd365e1..1aa613a25b8 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -2529,7 +2529,6 @@ public:
     {
       TABLE *tab= field->table;
       tab->covering_keys.intersect(field->part_of_key);
-      tab->merge_keys.merge(field->part_of_key);
       if (tab->read_set)
         bitmap_fast_test_and_set(tab->read_set, field->field_index);
       /* 
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 9bd0c062cdc..a3790043f9f 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -5027,7 +5027,6 @@ static void update_field_dependencies(THD *thd, Field *field, TABLE *table)
     */
       
     table->covering_keys.intersect(field->part_of_key);
-    table->merge_keys.merge(field->part_of_key);
 
     if (field->vcol_info)
       table->mark_virtual_col(field);
@@ -6376,7 +6375,6 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
         /* Mark field_1 used for table cache. */
         bitmap_set_bit(table_1->read_set, field_1->field_index);
         table_1->covering_keys.intersect(field_1->part_of_key);
-        table_1->merge_keys.merge(field_1->part_of_key);
       }
       if (field_2)
       {
@@ -6384,7 +6382,6 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
         /* Mark field_2 used for table cache. */
         bitmap_set_bit(table_2->read_set, field_2->field_index);
         table_2->covering_keys.intersect(field_2->part_of_key);
-        table_2->merge_keys.merge(field_2->part_of_key);
       }
 
       if (using_fields != NULL)
@@ -7479,7 +7476,6 @@ insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
         if (table)
         {
           table->covering_keys.intersect(field->part_of_key);
-          table->merge_keys.merge(field->part_of_key);
         }
         if (tables->is_natural_join)
         {
@@ -7499,7 +7495,6 @@ insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
             thd->lex->current_select->select_list_tables|=
               field_table->map;
             field_table->covering_keys.intersect(field->part_of_key);
-            field_table->merge_keys.merge(field->part_of_key);
             field_table->used_fields++;
           }
         }
diff --git a/sql/sql_base.h b/sql/sql_base.h
index 2c0e6850d04..8f363a73863 100644
--- a/sql/sql_base.h
+++ b/sql/sql_base.h
@@ -329,14 +329,12 @@ inline void setup_table_map(TABLE *table, TABLE_LIST *table_list, uint tablenr)
   table->force_index= table_list->force_index;
   table->force_index_order= table->force_index_group= 0;
   table->covering_keys= table->s->keys_for_keyread;
-  table->merge_keys.clear_all();
   TABLE_LIST *orig= table_list->select_lex ?
     table_list->select_lex->master_unit()->derived : 0;
   if (!orig || !orig->is_merged_derived())
   {
     /* Tables merged from derived were set up already.*/
     table->covering_keys= table->s->keys_for_keyread;
-    table->merge_keys.clear_all();
   }
 }
 
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 19e7668790e..bea3b14e607 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -4122,7 +4122,6 @@ void SELECT_LEX::update_used_tables()
           TABLE *tab= tl->table;
           tab->covering_keys= tab->s->keys_for_keyread;
           tab->covering_keys.intersect(tab->keys_in_use_for_query);
-          tab->merge_keys.clear_all();
           bitmap_clear_all(tab->read_set);
           if (tab->vcol_set)
             bitmap_clear_all(tab->vcol_set);
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index ed121191209..5eda6e9bbbb 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -16338,7 +16338,6 @@ create_tmp_table(THD *thd, TMP_TABLE_PARAM *param, List<Item> &fields,
   table->in_use= thd;
   table->quick_keys.init();
   table->covering_keys.init();
-  table->merge_keys.init();
   table->intersect_keys.init();
   table->keys_in_use_for_query.init();
   table->no_rows_with_nulls= param->force_not_null_cols;
diff --git a/sql/table.cc b/sql/table.cc
index 7e139652b6f..7d14f961721 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -2878,7 +2878,6 @@ enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
     goto err;
   outparam->quick_keys.init();
   outparam->covering_keys.init();
-  outparam->merge_keys.init();
   outparam->intersect_keys.init();
   outparam->keys_in_use_for_query.init();
 
diff --git a/sql/table.h b/sql/table.h
index 27439670a22..344655ebbbc 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -1042,7 +1042,7 @@ public:
     needed by the query without reading the row.
   */
   key_map covering_keys;
-  key_map quick_keys, merge_keys,intersect_keys;
+  key_map quick_keys, intersect_keys;
   /*
     A set of keys that can be used in the query that references this
     table.